Merge branch 'jc/diff-no-no-index'

* jc/diff-no-no-index:
  git diff --no-index: default to page like other diff frontends
  git-diff: allow  --no-index semantics a bit more
  "git diff": do not ignore index without --no-index
  diff-files: do not play --no-index games
  tests: do not use implicit "git diff --no-index"

60 files changed, 740 insertions, 738 deletions

diff --git a/Documentation/git-diff-files.txt b/Documentation/git-diff-files.txt
index 6d2ea16a25..ca1bb6a8ee 100644
--- a/Documentation/git-diff-files.txt
+++ b/Documentation/git-diff-files.txt
@@ -8,7 +8,7 @@ git-diff-files - Compares files in the working tree and the index
 
 SYNOPSIS
 --------
-'git-diff-files' [-q] [-0|-1|-2|-3|-c|--cc|--no-index] [<common diff options>] [<path>...]
+'git-diff-files' [-q] [-0|-1|-2|-3|-c|--cc] [<common diff options>] [<path>...]
 
 DESCRIPTION
 -----------
@@ -36,9 +36,6 @@ omit diff output for unmerged entries and just show "Unmerged".
 	diff, similar to the way 'diff-tree' shows a merge
 	commit with these flags.
 
---no-index::
-	Compare the two given files / directories.
-
 -q::
 	Remain silent even on nonexistent files
 
diff --git a/Makefile b/Makefile
index 4e36487c3c..cce5a6e1bf 100644
--- a/Makefile
+++ b/Makefile
@@ -405,6 +405,7 @@ LIB_OBJS += diffcore-order.o
 LIB_OBJS += diffcore-pickaxe.o
 LIB_OBJS += diffcore-rename.o
 LIB_OBJS += diff-delta.o
+LIB_OBJS += diff-no-index.o
 LIB_OBJS += diff-lib.o
 LIB_OBJS += diff.o
 LIB_OBJS += dir.o
diff --git a/builtin-diff-files.c b/builtin-diff-files.c
index 907392a1f3..384d871263 100644
--- a/builtin-diff-files.c
+++ b/builtin-diff-files.c
@@ -10,26 +10,54 @@
 #include "builtin.h"
 
 static const char diff_files_usage[] =
-"git-diff-files [-q] [-0/-1/2/3 |-c|--cc|--no-index] [<common diff options>] [<path>...]"
+"git-diff-files [-q] [-0/-1/2/3 |-c|--cc] [<common diff options>] [<path>...]"
 COMMON_DIFF_OPTIONS_HELP;
 
 int cmd_diff_files(int argc, const char **argv, const char *prefix)
 {
 	struct rev_info rev;
-	int nongit;
 	int result;
+	unsigned options = 0;
 
-	prefix = setup_git_directory_gently(&nongit);
 	init_revisions(&rev, prefix);
 	git_config(git_diff_basic_config, NULL); /* no "diff" UI options */
 	rev.abbrev = 0;
 
-	if (!setup_diff_no_index(&rev, argc, argv, nongit, prefix))
-		argc = 0;
-	else
-		argc = setup_revisions(argc, argv, &rev, NULL);
+	argc = setup_revisions(argc, argv, &rev, NULL);
+	while (1 < argc && argv[1][0] == '-') {
+		if (!strcmp(argv[1], "--base"))
+			rev.max_count = 1;
+		else if (!strcmp(argv[1], "--ours"))
+			rev.max_count = 2;
+		else if (!strcmp(argv[1], "--theirs"))
+			rev.max_count = 3;
+		else if (!strcmp(argv[1], "-q"))
+			options |= DIFF_SILENT_ON_REMOVED;
+		else
+			usage(diff_files_usage);
+		argv++; argc--;
+	}
 	if (!rev.diffopt.output_format)
 		rev.diffopt.output_format = DIFF_FORMAT_RAW;
-	result = run_diff_files_cmd(&rev, argc, argv);
+
+	/*
+	 * Make sure there are NO revision (i.e. pending object) parameter,
+	 * rev.max_count is reasonable (0 <= n <= 3), and
+	 * there is no other revision filtering parameters.
+	 */
+	if (rev.pending.nr ||
+	    rev.min_age != -1 || rev.max_age != -1 ||
+	    3 < rev.max_count)
+		usage(diff_files_usage);
+
+	if (rev.max_count == -1 &&
+	    (rev.diffopt.output_format & DIFF_FORMAT_PATCH))
+		rev.combine_merges = rev.dense_combined_merges = 1;
+
+	if (read_cache() < 0) {
+		perror("read_cache");
+		return -1;
+	}
+	result = run_diff_files(&rev, options);
 	return diff_result_code(&rev.diffopt, result);
 }
diff --git a/builtin-diff.c b/builtin-diff.c
index 583291a9c0..4c289e798a 100644
--- a/builtin-diff.c
+++ b/builtin-diff.c
@@ -202,6 +202,37 @@ static void refresh_index_quietly(void)
 	rollback_lock_file(lock_file);
 }
 
+static int builtin_diff_files(struct rev_info *revs, int argc, const char **argv)
+{
+	int result;
+	unsigned int options = 0;
+
+	while (1 < argc && argv[1][0] == '-') {
+		if (!strcmp(argv[1], "--base"))
+			revs->max_count = 1;
+		else if (!strcmp(argv[1], "--ours"))
+			revs->max_count = 2;
+		else if (!strcmp(argv[1], "--theirs"))
+			revs->max_count = 3;
+		else if (!strcmp(argv[1], "-q"))
+			options |= DIFF_SILENT_ON_REMOVED;
+		else
+			return error("invalid option: %s", argv[1]);
+		argv++; argc--;
+	}
+
+	if (revs->max_count == -1 &&
+	    (revs->diffopt.output_format & DIFF_FORMAT_PATCH))
+		revs->combine_merges = revs->dense_combined_merges = 1;
+
+	if (read_cache() < 0) {
+		perror("read_cache");
+		return -1;
+	}
+	result = run_diff_files(revs, options);
+	return diff_result_code(&revs->diffopt, result);
+}
+
 int cmd_diff(int argc, const char **argv, const char *prefix)
 {
 	int i;
@@ -230,6 +261,9 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
 	 * N=2, M=0:
 	 *      tree vs tree (diff-tree)
 	 *
+	 * N=0, M=0, P=2:
+	 *      compare two filesystem entities (aka --no-index).
+	 *
 	 * Other cases are errors.
 	 */
 
@@ -240,21 +274,21 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
 		diff_use_color_default = git_use_color_default;
 
 	init_revisions(&rev, prefix);
+
+	/* If this is a no-index diff, just run it and exit there. */
+	diff_no_index(&rev, argc, argv, nongit, prefix);
+
+	/* Otherwise, we are doing the usual "git" diff */
 	rev.diffopt.skip_stat_unmatch = !!diff_auto_refresh_index;
 
-	if (!setup_diff_no_index(&rev, argc, argv, nongit, prefix))
-		argc = 0;
-	else
-		argc = setup_revisions(argc, argv, &rev, NULL);
+	if (nongit)
+		die("Not a git repository");
+	argc = setup_revisions(argc, argv, &rev, NULL);
 	if (!rev.diffopt.output_format) {
 		rev.diffopt.output_format = DIFF_FORMAT_PATCH;
 		if (diff_setup_done(&rev.diffopt) < 0)
 			die("diff_setup_done failed");
 	}
-	if (rev.diffopt.prefix && nongit) {
-		rev.diffopt.prefix = NULL;
-		rev.diffopt.prefix_length = 0;
-	}
 	DIFF_OPT_SET(&rev.diffopt, ALLOW_EXTERNAL);
 	DIFF_OPT_SET(&rev.diffopt, RECURSIVE);
 
@@ -265,7 +299,8 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
 	if (!DIFF_OPT_TST(&rev.diffopt, EXIT_WITH_STATUS))
 		setup_pager();
 
-	/* Do we have --cached and not have a pending object, then
+	/*
+	 * Do we have --cached and not have a pending object, then
 	 * default to HEAD by hand.  Eek.
 	 */
 	if (!rev.pending.nr) {
@@ -333,7 +368,7 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
 	if (!ents) {
 		switch (blobs) {
 		case 0:
-			result = run_diff_files_cmd(&rev, argc, argv);
+			result = builtin_diff_files(&rev, argc, argv);
 			break;
 		case 1:
 			if (paths != 1)
diff --git a/diff-lib.c b/diff-lib.c
index fe2ccec7e6..b17722d66a 100644
--- a/diff-lib.c
+++ b/diff-lib.c
@@ -8,7 +8,6 @@
 #include "diffcore.h"
 #include "revision.h"
 #include "cache-tree.h"
-#include "path-list.h"
 #include "unpack-trees.h"
 #include "refs.h"
 
@@ -16,328 +15,6 @@
  * diff-files
  */
 
-static int read_directory(const char *path, struct path_list *list)
-{
-	DIR *dir;
-	struct dirent *e;
-
-	if (!(dir = opendir(path)))
-		return error("Could not open directory %s", path);
-
-	while ((e = readdir(dir)))
-		if (strcmp(".", e->d_name) && strcmp("..", e->d_name))
-			path_list_insert(e->d_name, list);
-
-	closedir(dir);
-	return 0;
-}
-
-static int get_mode(const char *path, int *mode)
-{
-	struct stat st;
-
-	if (!path || !strcmp(path, "/dev/null"))
-		*mode = 0;
-	else if (!strcmp(path, "-"))
-		*mode = create_ce_mode(0666);
-	else if (stat(path, &st))
-		return error("Could not access '%s'", path);
-	else
-		*mode = st.st_mode;
-	return 0;
-}
-
-static int queue_diff(struct diff_options *o,
-		const char *name1, const char *name2)
-{
-	int mode1 = 0, mode2 = 0;
-
-	if (get_mode(name1, &mode1) || get_mode(name2, &mode2))
-		return -1;
-
-	if (mode1 && mode2 && S_ISDIR(mode1) != S_ISDIR(mode2))
-		return error("file/directory conflict: %s, %s", name1, name2);
-
-	if (S_ISDIR(mode1) || S_ISDIR(mode2)) {
-		char buffer1[PATH_MAX], buffer2[PATH_MAX];
-		struct path_list p1 = {NULL, 0, 0, 1}, p2 = {NULL, 0, 0, 1};
-		int len1 = 0, len2 = 0, i1, i2, ret = 0;
-
-		if (name1 && read_directory(name1, &p1))
-			return -1;
-		if (name2 && read_directory(name2, &p2)) {
-			path_list_clear(&p1, 0);
-			return -1;
-		}
-
-		if (name1) {
-			len1 = strlen(name1);
-			if (len1 > 0 && name1[len1 - 1] == '/')
-				len1--;
-			memcpy(buffer1, name1, len1);
-			buffer1[len1++] = '/';
-		}
-
-		if (name2) {
-			len2 = strlen(name2);
-			if (len2 > 0 && name2[len2 - 1] == '/')
-				len2--;
-			memcpy(buffer2, name2, len2);
-			buffer2[len2++] = '/';
-		}
-
-		for (i1 = i2 = 0; !ret && (i1 < p1.nr || i2 < p2.nr); ) {
-			const char *n1, *n2;
-			int comp;
-
-			if (i1 == p1.nr)
-				comp = 1;
-			else if (i2 == p2.nr)
-				comp = -1;
-			else
-				comp = strcmp(p1.items[i1].path,
-					p2.items[i2].path);
-
-			if (comp > 0)
-				n1 = NULL;
-			else {
-				n1 = buffer1;
-				strncpy(buffer1 + len1, p1.items[i1++].path,
-						PATH_MAX - len1);
-			}
-
-			if (comp < 0)
-				n2 = NULL;
-			else {
-				n2 = buffer2;
-				strncpy(buffer2 + len2, p2.items[i2++].path,
-						PATH_MAX - len2);
-			}
-
-			ret = queue_diff(o, n1, n2);
-		}
-		path_list_clear(&p1, 0);
-		path_list_clear(&p2, 0);
-
-		return ret;
-	} else {
-		struct diff_filespec *d1, *d2;
-
-		if (DIFF_OPT_TST(o, REVERSE_DIFF)) {
-			unsigned tmp;
-			const char *tmp_c;
-			tmp = mode1; mode1 = mode2; mode2 = tmp;
-			tmp_c = name1; name1 = name2; name2 = tmp_c;
-		}
-
-		if (!name1)
-			name1 = "/dev/null";
-		if (!name2)
-			name2 = "/dev/null";
-		d1 = alloc_filespec(name1);
-		d2 = alloc_filespec(name2);
-		fill_filespec(d1, null_sha1, mode1);
-		fill_filespec(d2, null_sha1, mode2);
-
-		diff_queue(&diff_queued_diff, d1, d2);
-		return 0;
-	}
-}
-
-/*
- * Does the path name a blob in the working tree, or a directory
- * in the working tree?
- */
-static int is_in_index(const char *path)
-{
-	int len, pos;
-	struct cache_entry *ce;
-
-	len = strlen(path);
-	while (path[len-1] == '/')
-		len--;
-	if (!len)
-		return 1; /* "." */
-	pos = cache_name_pos(path, len);
-	if (0 <= pos)
-		return 1;
-	pos = -1 - pos;
-	while (pos < active_nr) {
-		ce = active_cache[pos++];
-		if (ce_namelen(ce) <= len ||
-		    strncmp(ce->name, path, len) ||
-		    (ce->name[len] > '/'))
-			break; /* path cannot be a prefix */
-		if (ce->name[len] == '/')
-			return 1;
-	}
-	return 0;
-}
-
-static int handle_diff_files_args(struct rev_info *revs,
-				  int argc, const char **argv,
-				  unsigned int *options)
-{
-	*options = 0;
-
-	/* revs->max_count == -2 means --no-index */
-	while (1 < argc && argv[1][0] == '-') {
-		if (!strcmp(argv[1], "--base"))
-			revs->max_count = 1;
-		else if (!strcmp(argv[1], "--ours"))
-			revs->max_count = 2;
-		else if (!strcmp(argv[1], "--theirs"))
-			revs->max_count = 3;
-		else if (!strcmp(argv[1], "-n") ||
-				!strcmp(argv[1], "--no-index")) {
-			revs->max_count = -2;
-			DIFF_OPT_SET(&revs->diffopt, EXIT_WITH_STATUS);
-			DIFF_OPT_SET(&revs->diffopt, NO_INDEX);
-		}
-		else if (!strcmp(argv[1], "-q"))
-			*options |= DIFF_SILENT_ON_REMOVED;
-		else
-			return error("invalid option: %s", argv[1]);
-		argv++; argc--;
-	}
-
-	if (revs->max_count == -1 && revs->diffopt.nr_paths == 2) {
-		/*
-		 * If two files are specified, and at least one is untracked,
-		 * default to no-index.
-		 */
-		read_cache();
-		if (!is_in_index(revs->diffopt.paths[0]) ||
-					!is_in_index(revs->diffopt.paths[1])) {
-			revs->max_count = -2;
-			DIFF_OPT_SET(&revs->diffopt, NO_INDEX);
-		}
-	}
-
-	/*
-	 * Make sure there are NO revision (i.e. pending object) parameter,
-	 * rev.max_count is reasonable (0 <= n <= 3),
-	 * there is no other revision filtering parameters.
-	 */
-	if (revs->pending.nr || revs->max_count > 3 ||
-	    revs->min_age != -1 || revs->max_age != -1)
-		return error("no revision allowed with diff-files");
-
-	if (revs->max_count == -1 &&
-	    (revs->diffopt.output_format & DIFF_FORMAT_PATCH))
-		revs->combine_merges = revs->dense_combined_merges = 1;
-
-	return 0;
-}
-
-static int is_outside_repo(const char *path, int nongit, const char *prefix)
-{
-	int i;
-	if (nongit || !strcmp(path, "-") || is_absolute_path(path))
-		return 1;
-	if (prefixcmp(path, "../"))
-		return 0;
-	if (!prefix)
-		return 1;
-	for (i = strlen(prefix); !prefixcmp(path, "../"); ) {
-		while (i > 0 && prefix[i - 1] != '/')
-			i--;
-		if (--i < 0)
-			return 1;
-		path += 3;
-	}
-	return 0;
-}
-
-int setup_diff_no_index(struct rev_info *revs,
-		int argc, const char ** argv, int nongit, const char *prefix)
-{
-	int i;
-	for (i = 1; i < argc; i++)
-		if (argv[i][0] != '-' || argv[i][1] == '\0')
-			break;
-		else if (!strcmp(argv[i], "--")) {
-			i++;
-			break;
-		} else if (i < argc - 3 && !strcmp(argv[i], "--no-index")) {
-			i = argc - 3;
-			DIFF_OPT_SET(&revs->diffopt, EXIT_WITH_STATUS);
-			break;
-		}
-	if (nongit && argc != i + 2)
-		die("git diff [--no-index] takes two paths");
-
-	if (argc != i + 2 || (!is_outside_repo(argv[i + 1], nongit, prefix) &&
-				!is_outside_repo(argv[i], nongit, prefix)))
-		return -1;
-
-	diff_setup(&revs->diffopt);
-	for (i = 1; i < argc - 2; )
-		if (!strcmp(argv[i], "--no-index"))
-			i++;
-		else {
-			int j = diff_opt_parse(&revs->diffopt,
-					argv + i, argc - i);
-			if (!j)
-				die("invalid diff option/value: %s", argv[i]);
-			i += j;
-		}
-
-	if (prefix) {
-		int len = strlen(prefix);
-
-		revs->diffopt.paths = xcalloc(2, sizeof(char*));
-		for (i = 0; i < 2; i++) {
-			const char *p = argv[argc - 2 + i];
-			/*
-			 * stdin should be spelled as '-'; if you have
-			 * path that is '-', spell it as ./-.
-			 */
-			p = (strcmp(p, "-")
-			     ? xstrdup(prefix_filename(prefix, len, p))
-			     : p);
-			revs->diffopt.paths[i] = p;
-		}
-	}
-	else
-		revs->diffopt.paths = argv + argc - 2;
-	revs->diffopt.nr_paths = 2;
-	DIFF_OPT_SET(&revs->diffopt, NO_INDEX);
-	revs->max_count = -2;
-	if (diff_setup_done(&revs->diffopt) < 0)
-		die("diff_setup_done failed");
-	return 0;
-}
-
-int run_diff_files_cmd(struct rev_info *revs, int argc, const char **argv)
-{
-	unsigned int options;
-
-	if (handle_diff_files_args(revs, argc, argv, &options))
-		return -1;
-
-	if (DIFF_OPT_TST(&revs->diffopt, NO_INDEX)) {
-		if (revs->diffopt.nr_paths != 2)
-			return error("need two files/directories with --no-index");
-		if (queue_diff(&revs->diffopt, revs->diffopt.paths[0],
-				revs->diffopt.paths[1]))
-			return -1;
-		diffcore_std(&revs->diffopt);
-		diff_flush(&revs->diffopt);
-		/*
-		 * The return code for --no-index imitates diff(1):
-		 * 0 = no changes, 1 = changes, else error
-		 */
-		return revs->diffopt.found_changes;
-	}
-
-	if (read_cache() < 0) {
-		perror("read_cache");
-		return -1;
-	}
-	return run_diff_files(revs, options);
-}
-
 /*
  * Has the work tree entity been removed?
  *
diff --git a/diff-no-index.c b/diff-no-index.c
new file mode 100644
index 0000000000..f6994cf5fb
--- /dev/null
+++ b/diff-no-index.c
@@ -0,0 +1,263 @@
+/*
+ * "diff --no-index" support
+ * Copyright (c) 2007 by Johannes Schindelin
+ * Copyright (c) 2008 by Junio C Hamano
+ */
+
+#include "cache.h"
+#include "color.h"
+#include "commit.h"
+#include "blob.h"
+#include "tag.h"
+#include "diff.h"
+#include "diffcore.h"
+#include "revision.h"
+#include "log-tree.h"
+#include "builtin.h"
+#include "path-list.h"
+
+static int read_directory(const char *path, struct path_list *list)
+{
+	DIR *dir;
+	struct dirent *e;
+
+	if (!(dir = opendir(path)))
+		return error("Could not open directory %s", path);
+
+	while ((e = readdir(dir)))
+		if (strcmp(".", e->d_name) && strcmp("..", e->d_name))
+			path_list_insert(e->d_name, list);
+
+	closedir(dir);
+	return 0;
+}
+
+static int get_mode(const char *path, int *mode)
+{
+	struct stat st;
+
+	if (!path || !strcmp(path, "/dev/null"))
+		*mode = 0;
+	else if (!strcmp(path, "-"))
+		*mode = create_ce_mode(0666);
+	else if (stat(path, &st))
+		return error("Could not access '%s'", path);
+	else
+		*mode = st.st_mode;
+	return 0;
+}
+
+static int queue_diff(struct diff_options *o,
+		const char *name1, const char *name2)
+{
+	int mode1 = 0, mode2 = 0;
+
+	if (get_mode(name1, &mode1) || get_mode(name2, &mode2))
+		return -1;
+
+	if (mode1 && mode2 && S_ISDIR(mode1) != S_ISDIR(mode2))
+		return error("file/directory conflict: %s, %s", name1, name2);
+
+	if (S_ISDIR(mode1) || S_ISDIR(mode2)) {
+		char buffer1[PATH_MAX], buffer2[PATH_MAX];
+		struct path_list p1 = {NULL, 0, 0, 1}, p2 = {NULL, 0, 0, 1};
+		int len1 = 0, len2 = 0, i1, i2, ret = 0;
+
+		if (name1 && read_directory(name1, &p1))
+			return -1;
+		if (name2 && read_directory(name2, &p2)) {
+			path_list_clear(&p1, 0);
+			return -1;
+		}
+
+		if (name1) {
+			len1 = strlen(name1);
+			if (len1 > 0 && name1[len1 - 1] == '/')
+				len1--;
+			memcpy(buffer1, name1, len1);
+			buffer1[len1++] = '/';
+		}
+
+		if (name2) {
+			len2 = strlen(name2);
+			if (len2 > 0 && name2[len2 - 1] == '/')
+				len2--;
+			memcpy(buffer2, name2, len2);
+			buffer2[len2++] = '/';
+		}
+
+		for (i1 = i2 = 0; !ret && (i1 < p1.nr || i2 < p2.nr); ) {
+			const char *n1, *n2;
+			int comp;
+
+			if (i1 == p1.nr)
+				comp = 1;
+			else if (i2 == p2.nr)
+				comp = -1;
+			else
+				comp = strcmp(p1.items[i1].path,
+					p2.items[i2].path);
+
+			if (comp > 0)
+				n1 = NULL;
+			else {
+				n1 = buffer1;
+				strncpy(buffer1 + len1, p1.items[i1++].path,
+						PATH_MAX - len1);
+			}
+
+			if (comp < 0)
+				n2 = NULL;
+			else {
+				n2 = buffer2;
+				strncpy(buffer2 + len2, p2.items[i2++].path,
+						PATH_MAX - len2);
+			}
+
+			ret = queue_diff(o, n1, n2);
+		}
+		path_list_clear(&p1, 0);
+		path_list_clear(&p2, 0);
+
+		return ret;
+	} else {
+		struct diff_filespec *d1, *d2;
+
+		if (DIFF_OPT_TST(o, REVERSE_DIFF)) {
+			unsigned tmp;
+			const char *tmp_c;
+			tmp = mode1; mode1 = mode2; mode2 = tmp;
+			tmp_c = name1; name1 = name2; name2 = tmp_c;
+		}
+
+		if (!name1)
+			name1 = "/dev/null";
+		if (!name2)
+			name2 = "/dev/null";
+		d1 = alloc_filespec(name1);
+		d2 = alloc_filespec(name2);
+		fill_filespec(d1, null_sha1, mode1);
+		fill_filespec(d2, null_sha1, mode2);
+
+		diff_queue(&diff_queued_diff, d1, d2);
+		return 0;
+	}
+}
+
+static int path_outside_repo(const char *path)
+{
+	/*
+	 * We have already done setup_git_directory_gently() so we
+	 * know we are inside a git work tree already.
+	 */
+	const char *work_tree;
+	size_t len;
+
+	if (!is_absolute_path(path))
+		return 0;
+	work_tree = get_git_work_tree();
+	len = strlen(work_tree);
+	if (strncmp(path, work_tree, len) ||
+	    (path[len] != '\0' && path[len] != '/'))
+		return 1;
+	return 0;
+}
+
+void diff_no_index(struct rev_info *revs,
+		   int argc, const char **argv,
+		   int nongit, const char *prefix)
+{
+	int i;
+	int no_index = 0;
+	unsigned options = 0;
+
+	/* Were we asked to do --no-index explicitly? */
+	for (i = 1; i < argc; i++) {
+		if (!strcmp(argv[i], "--"))
+			return;
+		if (!strcmp(argv[i], "--no-index"))
+			no_index = 1;
+		if (argv[i][0] != '-')
+			break;
+	}
+
+	if (!no_index && !nongit) {
+		/*
+		 * Inside a git repository, without --no-index.  Only
+		 * when a path outside the repository is given,
+		 * e.g. "git diff /var/tmp/[12]", or "git diff
+		 * Makefile /var/tmp/Makefile", allow it to be used as
+		 * a colourful "diff" replacement.
+		 */
+		if ((argc != i + 2) ||
+		    (!path_outside_repo(argv[i]) &&
+		     !path_outside_repo(argv[i+1])))
+			return;
+	}
+	if (argc != i + 2)
+		die("git diff %s takes two paths",
+		    no_index ? "--no-index" : "[--no-index]");
+
+	/*
+	 * If the user asked for our exit code then don't start a
+	 * pager or we would end up reporting its exit code instead.
+	 */
+	if (!DIFF_OPT_TST(&revs->diffopt, EXIT_WITH_STATUS))
+		setup_pager();
+
+	diff_setup(&revs->diffopt);
+	if (!revs->diffopt.output_format)
+		revs->diffopt.output_format = DIFF_FORMAT_PATCH;
+	for (i = 1; i < argc - 2; ) {
+		int j;
+		if (!strcmp(argv[i], "--no-index"))
+			i++;
+		else if (!strcmp(argv[1], "-q"))
+			options |= DIFF_SILENT_ON_REMOVED;
+		else {
+			j = diff_opt_parse(&revs->diffopt, argv + i, argc - i);
+			if (!j)
+				die("invalid diff option/value: %s", argv[i]);
+			i += j;
+		}
+	}
+
+	if (prefix) {
+		int len = strlen(prefix);
+
+		revs->diffopt.paths = xcalloc(2, sizeof(char*));
+		for (i = 0; i < 2; i++) {
+			const char *p = argv[argc - 2 + i];
+			/*
+			 * stdin should be spelled as '-'; if you have
+			 * path that is '-', spell it as ./-.
+			 */
+			p = (strcmp(p, "-")
+			     ? xstrdup(prefix_filename(prefix, len, p))
+			     : p);
+			revs->diffopt.paths[i] = p;
+		}
+	}
+	else
+		revs->diffopt.paths = argv + argc - 2;
+	revs->diffopt.nr_paths = 2;
+
+	DIFF_OPT_SET(&revs->diffopt, EXIT_WITH_STATUS);
+	DIFF_OPT_SET(&revs->diffopt, NO_INDEX);
+
+	revs->max_count = -2;
+	if (diff_setup_done(&revs->diffopt) < 0)
+		die("diff_setup_done failed");
+
+	if (queue_diff(&revs->diffopt, revs->diffopt.paths[0],
+		       revs->diffopt.paths[1]))
+		exit(1);
+	diffcore_std(&revs->diffopt);
+	diff_flush(&revs->diffopt);
+
+	/*
+	 * The return code for --no-index imitates diff(1):
+	 * 0 = no changes, 1 = changes, else error
+	 */
+	exit(revs->diffopt.found_changes);
+}
diff --git a/diff.h b/diff.h
index b0b700a5f6..5dc0cb595b 100644
--- a/diff.h
+++ b/diff.h
@@ -251,10 +251,6 @@ extern const char *diff_unique_abbrev(const unsigned char *, int);
 /* report racily-clean paths as modified */
 #define DIFF_RACY_IS_MODIFIED 02
 extern int run_diff_files(struct rev_info *revs, unsigned int option);
-extern int setup_diff_no_index(struct rev_info *revs,
-		int argc, const char ** argv, int nongit, const char *prefix);
-extern int run_diff_files_cmd(struct rev_info *revs, int argc, const char **argv);
-
 extern int run_diff_index(struct rev_info *revs, int cached);
 
 extern int do_diff_cache(const unsigned char *, struct diff_options *);
@@ -262,4 +258,6 @@ extern int diff_flush_patch_id(struct diff_options *, unsigned char *);
 
 extern int diff_result_code(struct diff_options *, int);
 
+extern void diff_no_index(struct rev_info *, int, const char **, int, const char *);
+
 #endif /* DIFF_H */
diff --git a/git.c b/git.c
index 2c9004f02e..272bf03da3 100644
--- a/git.c
+++ b/git.c
@@ -294,7 +294,7 @@ static void handle_internal_command(int argc, const char **argv)
 		{ "count-objects", cmd_count_objects, RUN_SETUP },
 		{ "describe", cmd_describe, RUN_SETUP },
 		{ "diff", cmd_diff },
-		{ "diff-files", cmd_diff_files },
+		{ "diff-files", cmd_diff_files, RUN_SETUP },
 		{ "diff-index", cmd_diff_index, RUN_SETUP },
 		{ "diff-tree", cmd_diff_tree, RUN_SETUP },
 		{ "fast-export", cmd_fast_export, RUN_SETUP },
diff --git a/t/diff-lib.sh b/t/diff-lib.sh
index 28b941c493..4bddeb591e 100644
--- a/t/diff-lib.sh
+++ b/t/diff-lib.sh
@@ -11,7 +11,7 @@ compare_diff_raw () {
 
     sed -e "$sanitize_diff_raw" <"$1" >.tmp-1
     sed -e "$sanitize_diff_raw" <"$2" >.tmp-2
-    git diff .tmp-1 .tmp-2 && rm -f .tmp-1 .tmp-2
+    test_cmp .tmp-1 .tmp-2 && rm -f .tmp-1 .tmp-2
 }
 
 sanitize_diff_raw_z='/^:/s/ '"$_x40"' '"$_x40"' \([A-Z]\)[0-9]*$/ X X \1#/'
@@ -23,7 +23,7 @@ compare_diff_raw_z () {
 
     perl -pe 'y/\000/\012/' <"$1" | sed -e "$sanitize_diff_raw_z" >.tmp-1
     perl -pe 'y/\000/\012/' <"$2" | sed -e "$sanitize_diff_raw_z" >.tmp-2
-    git diff .tmp-1 .tmp-2 && rm -f .tmp-1 .tmp-2
+    test_cmp .tmp-1 .tmp-2 && rm -f .tmp-1 .tmp-2
 }
 
 compare_diff_patch () {
@@ -37,5 +37,5 @@ compare_diff_patch () {
 	/^[dis]*imilarity index [0-9]*%$/d
 	/^index [0-9a-f]*\.\.[0-9a-f]/d
     ' <"$2" >.tmp-2
-    git diff .tmp-1 .tmp-2 && rm -f .tmp-1 .tmp-2
+    test_cmp .tmp-1 .tmp-2 && rm -f .tmp-1 .tmp-2
 }
diff --git a/t/t0030-stripspace.sh b/t/t0030-stripspace.sh
index 3ecdd6626a..ccb0a3cb61 100755
--- a/t/t0030-stripspace.sh
+++ b/t/t0030-stripspace.sh
@@ -16,96 +16,96 @@ test_expect_success \
     'long lines without spaces should be unchanged' '
     echo "$ttt" >expect &&
     git stripspace <expect >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     echo "$ttt$ttt" >expect &&
     git stripspace <expect >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     echo "$ttt$ttt$ttt" >expect &&
     git stripspace <expect >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     echo "$ttt$ttt$ttt$ttt" >expect &&
     git stripspace <expect >actual &&
-    git diff expect actual
+    test_cmp expect actual
 '
 
 test_expect_success \
     'lines with spaces at the beginning should be unchanged' '
     echo "$sss$ttt" >expect &&
     git stripspace <expect >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     echo "$sss$sss$ttt" >expect &&
     git stripspace <expect >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     echo "$sss$sss$sss$ttt" >expect &&
     git stripspace <expect >actual &&
-    git diff expect actual
+    test_cmp expect actual
 '
 
 test_expect_success \
     'lines with intermediate spaces should be unchanged' '
     echo "$ttt$sss$ttt" >expect &&
     git stripspace <expect >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     echo "$ttt$sss$sss$ttt" >expect &&
     git stripspace <expect >actual &&
-    git diff expect actual
+    test_cmp expect actual
 '
 
 test_expect_success \
     'consecutive blank lines should be unified' '
     printf "$ttt\n\n$ttt\n" > expect &&
     printf "$ttt\n\n\n\n\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt$ttt\n\n$ttt\n" > expect &&
     printf "$ttt$ttt\n\n\n\n\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt$ttt$ttt\n\n$ttt\n" > expect &&
     printf "$ttt$ttt$ttt\n\n\n\n\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n\n$ttt\n" > expect &&
     printf "$ttt\n\n\n\n\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n\n$ttt$ttt\n" > expect &&
     printf "$ttt\n\n\n\n\n$ttt$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n\n$ttt$ttt$ttt\n" > expect &&
     printf "$ttt\n\n\n\n\n$ttt$ttt$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n\n$ttt\n" > expect &&
     printf "$ttt\n\t\n \n\n  \t\t\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt$ttt\n\n$ttt\n" > expect &&
     printf "$ttt$ttt\n\t\n \n\n  \t\t\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt$ttt$ttt\n\n$ttt\n" > expect &&
     printf "$ttt$ttt$ttt\n\t\n \n\n  \t\t\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n\n$ttt\n" > expect &&
     printf "$ttt\n\t\n \n\n  \t\t\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n\n$ttt$ttt\n" > expect &&
     printf "$ttt\n\t\n \n\n  \t\t\n$ttt$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n\n$ttt$ttt$ttt\n" > expect &&
     printf "$ttt\n\t\n \n\n  \t\t\n$ttt$ttt$ttt\n" | git stripspace >actual &&
-    git diff expect actual
+    test_cmp expect actual
 '
 
 test_expect_success \
@@ -113,114 +113,114 @@ test_expect_success \
     > expect &&
 
     printf "\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "\n\n\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$sss\n$sss\n$sss\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$sss$sss\n$sss\n\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "\n$sss\n$sss$sss\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$sss$sss$sss$sss\n\n\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "\n$sss$sss$sss$sss\n\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "\n\n$sss$sss$sss$sss\n" | git stripspace >actual &&
-    git diff expect actual
+    test_cmp expect actual
 '
 
 test_expect_success \
     'consecutive blank lines at the beginning should be removed' '
     printf "$ttt\n" > expect &&
     printf "\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n" > expect &&
     printf "\n\n\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt$ttt\n" > expect &&
     printf "\n\n\n$ttt$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt$ttt$ttt\n" > expect &&
     printf "\n\n\n$ttt$ttt$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt$ttt$ttt$ttt\n" > expect &&
     printf "\n\n\n$ttt$ttt$ttt$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n" > expect &&
 
     printf "$sss\n$sss\n$sss\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "\n$sss\n$sss$sss\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$sss$sss\n$sss\n\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$sss$sss$sss\n\n\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "\n$sss$sss$sss\n\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "\n\n$sss$sss$sss\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual
+    test_cmp expect actual
 '
 
 test_expect_success \
     'consecutive blank lines at the end should be removed' '
     printf "$ttt\n" > expect &&
     printf "$ttt\n\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n" > expect &&
     printf "$ttt\n\n\n\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt$ttt\n" > expect &&
     printf "$ttt$ttt\n\n\n\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt$ttt$ttt\n" > expect &&
     printf "$ttt$ttt$ttt\n\n\n\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt$ttt$ttt$ttt\n" > expect &&
     printf "$ttt$ttt$ttt$ttt\n\n\n\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n" > expect &&
 
     printf "$ttt\n$sss\n$sss\n$sss\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n\n$sss\n$sss$sss\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n$sss$sss\n$sss\n\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n$sss$sss$sss\n\n\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n\n$sss$sss$sss\n\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n\n\n$sss$sss$sss\n" | git stripspace >actual &&
-    git diff expect actual
+    test_cmp expect actual
 '
 
 test_expect_success \
@@ -257,27 +257,27 @@ test_expect_success \
     'text plus spaces without newline should show the correct lines' '
     printf "$ttt\n" >expect &&
     printf "$ttt$sss" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n" >expect &&
     printf "$ttt$sss$sss" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n" >expect &&
     printf "$ttt$sss$sss$sss" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt$ttt\n" >expect &&
     printf "$ttt$ttt$sss" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt$ttt\n" >expect &&
     printf "$ttt$ttt$sss$sss" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt$ttt$ttt\n" >expect &&
     printf "$ttt$ttt$ttt$sss" | git stripspace >actual &&
-    git diff expect actual
+    test_cmp expect actual
 '
 
 test_expect_success \
@@ -294,27 +294,27 @@ test_expect_success \
     'text plus spaces at end should be cleaned and newline must remain' '
     echo "$ttt" >expect &&
     echo "$ttt$sss" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     echo "$ttt" >expect &&
     echo "$ttt$sss$sss" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     echo "$ttt" >expect &&
     echo "$ttt$sss$sss$sss" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     echo "$ttt$ttt" >expect &&
     echo "$ttt$ttt$sss" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     echo "$ttt$ttt" >expect &&
     echo "$ttt$ttt$sss$sss" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     echo "$ttt$ttt$ttt" >expect &&
     echo "$ttt$ttt$ttt$sss" | git stripspace >actual &&
-    git diff expect actual
+    test_cmp expect actual
 '
 
 # spaces only:
@@ -324,19 +324,19 @@ test_expect_success \
     printf "" >expect &&
 
     echo | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     echo "$sss" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     echo "$sss$sss" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     echo "$sss$sss$sss" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     echo "$sss$sss$sss$sss" | git stripspace >actual &&
-    git diff expect actual
+    test_cmp expect actual
 '
 
 test_expect_success \
@@ -353,43 +353,43 @@ test_expect_success \
     printf "" >expect &&
 
     printf "" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$sss$sss" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$sss$sss$sss" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$sss$sss$sss$sss" | git stripspace >actual &&
-    git diff expect actual
+    test_cmp expect actual
 '
 
 test_expect_success \
     'consecutive text lines should be unchanged' '
     printf "$ttt$ttt\n$ttt\n" >expect &&
     printf "$ttt$ttt\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n$ttt$ttt\n$ttt\n" >expect &&
     printf "$ttt\n$ttt$ttt\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n$ttt\n$ttt\n$ttt$ttt\n" >expect &&
     printf "$ttt\n$ttt\n$ttt\n$ttt$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n$ttt\n\n$ttt$ttt\n$ttt\n" >expect &&
     printf "$ttt\n$ttt\n\n$ttt$ttt\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt$ttt\n\n$ttt\n$ttt$ttt\n" >expect &&
     printf "$ttt$ttt\n\n$ttt\n$ttt$ttt\n" | git stripspace >actual &&
-    git diff expect actual &&
+    test_cmp expect actual &&
 
     printf "$ttt\n$ttt$ttt\n\n$ttt\n" >expect &&
     printf "$ttt\n$ttt$ttt\n\n$ttt\n" | git stripspace >actual &&
-    git diff expect actual
+    test_cmp expect actual
 '
 
 test_expect_success 'strip comments, too' '
diff --git a/t/t0040-parse-options.sh b/t/t0040-parse-options.sh
index c23f0ace85..9965cfa1dc 100755
--- a/t/t0040-parse-options.sh
+++ b/t/t0040-parse-options.sh
@@ -29,7 +29,7 @@ EOF
 test_expect_success 'test help' '
 	! test-parse-options -h > output 2> output.err &&
 	test ! -s output &&
-	git diff expect.err output.err
+	test_cmp expect.err output.err
 '
 
 cat > expect << EOF
@@ -40,7 +40,7 @@ EOF
 
 test_expect_success 'short options' '
 	test-parse-options -s123 -b -i 1729 -b > output 2> output.err &&
-	git diff expect output &&
+	test_cmp expect output &&
 	test ! -s output.err
 '
 cat > expect << EOF
@@ -53,7 +53,7 @@ test_expect_success 'long options' '
 	test-parse-options --boolean --integer 1729 --boolean --string2=321 \
 		> output 2> output.err &&
 	test ! -s output.err &&
-	git diff expect output
+	test_cmp expect output
 '
 
 cat > expect << EOF
@@ -69,7 +69,7 @@ test_expect_success 'intermingled arguments' '
 	test-parse-options a1 --string 123 b1 --boolean -j 13 -- --boolean \
 		> output 2> output.err &&
 	test ! -s output.err &&
-	git diff expect output
+	test_cmp expect output
 '
 
 cat > expect << EOF
@@ -81,13 +81,13 @@ EOF
 test_expect_success 'unambiguously abbreviated option' '
 	test-parse-options --int 2 --boolean --no-bo > output 2> output.err &&
 	test ! -s output.err &&
-	git diff expect output
+	test_cmp expect output
 '
 
 test_expect_success 'unambiguously abbreviated option with "="' '
 	test-parse-options --int=2 > output 2> output.err &&
 	test ! -s output.err &&
-	git diff expect output
+	test_cmp expect output
 '
 
 test_expect_success 'ambiguously abbreviated option' '
@@ -104,7 +104,7 @@ EOF
 test_expect_success 'non ambiguous option (after two options it abbreviates)' '
 	test-parse-options --st 123 > output 2> output.err &&
 	test ! -s output.err &&
-	git diff expect output
+	test_cmp expect output
 '
 
 cat > expect.err << EOF
@@ -114,7 +114,7 @@ EOF
 test_expect_success 'detect possible typos' '
 	! test-parse-options -boolean > output 2> output.err &&
 	test ! -s output &&
-	git diff expect.err output.err
+	test_cmp expect.err output.err
 '
 
 cat > expect <<EOF
@@ -127,7 +127,7 @@ EOF
 test_expect_success 'keep some options as arguments' '
 	test-parse-options --quux > output 2> output.err &&
         test ! -s output.err &&
-        git diff expect output
+        test_cmp expect output
 '
 
 test_done
diff --git a/t/t1000-read-tree-m-3way.sh b/t/t1000-read-tree-m-3way.sh
index 17f519f547..807fb83af8 100755
--- a/t/t1000-read-tree-m-3way.sh
+++ b/t/t1000-read-tree-m-3way.sh
@@ -131,7 +131,7 @@ _x40="$_x40$_x40$_x40$_x40$_x40$_x40$_x40$_x40"
 
 check_result () {
     git ls-files --stage | sed -e 's/ '"$_x40"' / X /' >current &&
-    git diff expected current
+    test_cmp expected current
 }
 
 # This is done on an empty work directory, which is the normal
diff --git a/t/t1001-read-tree-m-2way.sh b/t/t1001-read-tree-m-2way.sh
index b01b0037a0..4b44e131b2 100755
--- a/t/t1001-read-tree-m-2way.sh
+++ b/t/t1001-read-tree-m-2way.sh
@@ -33,7 +33,7 @@ compare_change () {
 	    -e '/^--- /d; /^+++ /d; /^@@ /d;' \
 	    -e 's/^\([-+][0-7][0-7][0-7][0-7][0-7][0-7]\) '"$_x40"' /\1 X /p' \
 	    "$1"
-	git diff expected current
+	test_cmp expected current
 }
 
 check_cache_at () {
@@ -86,7 +86,7 @@ test_expect_success \
     'rm -f .git/index &&
      read_tree_twoway $treeH $treeM &&
      git ls-files --stage >1-3.out &&
-     git diff M.out 1-3.out &&
+     test_cmp M.out 1-3.out &&
      check_cache_at bozbar dirty &&
      check_cache_at frotz dirty &&
      check_cache_at nitfol dirty'
@@ -101,7 +101,7 @@ test_expect_success \
      git update-index --add yomin &&
      read_tree_twoway $treeH $treeM &&
      git ls-files --stage >4.out || return 1
-     git diff M.out 4.out >4diff.out
+     git diff --no-index M.out 4.out >4diff.out
      compare_change 4diff.out expected &&
      check_cache_at yomin clean'
 
@@ -115,7 +115,7 @@ test_expect_success \
      echo yomin yomin >yomin &&
      read_tree_twoway $treeH $treeM &&
      git ls-files --stage >5.out || return 1
-     git diff M.out 5.out >5diff.out
+     git diff --no-index M.out 5.out >5diff.out
      compare_change 5diff.out expected &&
      check_cache_at yomin dirty'
 
@@ -127,7 +127,7 @@ test_expect_success \
      git update-index --add frotz &&
      read_tree_twoway $treeH $treeM &&
      git ls-files --stage >6.out &&
-     git diff M.out 6.out &&
+     test_cmp M.out 6.out &&
      check_cache_at frotz clean'
 
 test_expect_success \
@@ -140,7 +140,7 @@ test_expect_success \
      echo frotz frotz >frotz &&
      read_tree_twoway $treeH $treeM &&
      git ls-files --stage >7.out &&
-     git diff M.out 7.out &&
+     test_cmp M.out 7.out &&
      check_cache_at frotz dirty'
 
 test_expect_success \
@@ -171,7 +171,7 @@ test_expect_success \
      git update-index --add rezrov &&
      read_tree_twoway $treeH $treeM &&
      git ls-files --stage >10.out &&
-     git diff M.out 10.out'
+     test_cmp M.out 10.out'
 
 test_expect_success \
     '11 - dirty path removed.' \
@@ -216,7 +216,7 @@ test_expect_success \
      git update-index --add nitfol &&
      read_tree_twoway $treeH $treeM &&
      git ls-files --stage >14.out || return 1
-     git diff M.out 14.out >14diff.out
+     git diff --no-index M.out 14.out >14diff.out
      compare_change 14diff.out expected &&
      check_cache_at nitfol clean'
 
@@ -230,7 +230,7 @@ test_expect_success \
      echo nitfol nitfol nitfol >nitfol &&
      read_tree_twoway $treeH $treeM &&
      git ls-files --stage >15.out || return 1
-     git diff M.out 15.out >15diff.out
+     git diff --no-index M.out 15.out >15diff.out
      compare_change 15diff.out expected &&
      check_cache_at nitfol dirty'
 
@@ -262,7 +262,7 @@ test_expect_success \
      git update-index --add bozbar &&
      read_tree_twoway $treeH $treeM &&
      git ls-files --stage >18.out &&
-     git diff M.out 18.out &&
+     test_cmp M.out 18.out &&
      check_cache_at bozbar clean'
 
 test_expect_success \
@@ -275,7 +275,7 @@ test_expect_success \
      echo gnusto gnusto >bozbar &&
      read_tree_twoway $treeH $treeM &&
      git ls-files --stage >19.out &&
-     git diff M.out 19.out &&
+     test_cmp M.out 19.out &&
      check_cache_at bozbar dirty'
 
 test_expect_success \
@@ -287,7 +287,7 @@ test_expect_success \
      git update-index --add bozbar &&
      read_tree_twoway $treeH $treeM &&
      git ls-files --stage >20.out &&
-     git diff M.out 20.out &&
+     test_cmp M.out 20.out &&
      check_cache_at bozbar dirty'
 
 test_expect_success \
@@ -337,7 +337,7 @@ test_expect_success \
      git update-index --add DF &&
      read_tree_twoway $treeDF $treeDFDF &&
      git ls-files --stage >DFDFcheck.out &&
-     git diff DFDF.out DFDFcheck.out &&
+     test_cmp DFDF.out DFDFcheck.out &&
      check_cache_at DF/DF dirty &&
      :'
 
diff --git a/t/t1002-read-tree-m-u-2way.sh b/t/t1002-read-tree-m-u-2way.sh
index 42e5cf8181..e04990eafd 100755
--- a/t/t1002-read-tree-m-u-2way.sh
+++ b/t/t1002-read-tree-m-u-2way.sh
@@ -16,7 +16,7 @@ compare_change () {
 	sed >current \
 	    -e '/^--- /d; /^+++ /d; /^@@ /d;' \
 	    -e 's/^\(.[0-7][0-7][0-7][0-7][0-7][0-7]\) '"$_x40"' /\1 X /' "$1"
-	git diff expected current
+	test_cmp expected current
 }
 
 check_cache_at () {
diff --git a/t/t1300-repo-config.sh b/t/t1300-repo-config.sh
index a675cbb51b..afe7e663fb 100755
--- a/t/t1300-repo-config.sh
+++ b/t/t1300-repo-config.sh
@@ -427,13 +427,13 @@ cat > expect << EOF
 weird
 EOF
 
-test_expect_success "rename succeeded" "git diff expect .git/config"
+test_expect_success "rename succeeded" "test_cmp expect .git/config"
 
 test_expect_success "rename non-existing section" '
 	! git config --rename-section branch."world domination" branch.drei
 '
 
-test_expect_success "rename succeeded" "git diff expect .git/config"
+test_expect_success "rename succeeded" "test_cmp expect .git/config"
 
 test_expect_success "rename another section" \
 	'git config --rename-section branch."1 234 blabl/a" branch.drei'
@@ -449,7 +449,7 @@ cat > expect << EOF
 weird
 EOF
 
-test_expect_success "rename succeeded" "git diff expect .git/config"
+test_expect_success "rename succeeded" "test_cmp expect .git/config"
 
 cat >> .git/config << EOF
   [branch "zwei"] a = 1 [branch "vier"]
@@ -465,7 +465,7 @@ weird
 EOF
 
 test_expect_success "section was removed properly" \
-	"git diff -u expect .git/config"
+	"test_cmp expect .git/config"
 
 rm .git/config
 
diff --git a/t/t1303-wacky-config.sh b/t/t1303-wacky-config.sh
index f366b53fb6..f98f4c5179 100755
--- a/t/t1303-wacky-config.sh
+++ b/t/t1303-wacky-config.sh
@@ -11,7 +11,7 @@ setup() {
 check() {
 	echo "$2" >expected
 	git config --get "$1" >actual
-	git diff actual expected
+	test_cmp actual expected
 }
 
 test_expect_success 'modify same key' '
diff --git a/t/t1502-rev-parse-parseopt.sh b/t/t1502-rev-parse-parseopt.sh
index 762af5faf7..d24a47d114 100755
--- a/t/t1502-rev-parse-parseopt.sh
+++ b/t/t1502-rev-parse-parseopt.sh
@@ -37,7 +37,7 @@ C?        option C with an optional argument
 Extras
 extra1    line above used to cause a segfault but no longer does
 EOF
-	git diff expect.err output.err
+	test_cmp expect.err output.err
 '
 
 test_done
diff --git a/t/t3001-ls-files-others-exclude.sh b/t/t3001-ls-files-others-exclude.sh
index 55f057cebe..1caeacafa7 100755
--- a/t/t3001-ls-files-others-exclude.sh
+++ b/t/t3001-ls-files-others-exclude.sh
@@ -65,7 +65,7 @@ test_expect_success \
        --exclude-per-directory=.gitignore \
        --exclude-from=.git/ignore \
        >output &&
-     git diff expect output'
+     test_cmp expect output'
 
 # Test \r\n (MSDOS-like systems)
 printf '*.1\r\n/*.3\r\n!*.6\r\n' >.gitignore
@@ -77,7 +77,7 @@ test_expect_success \
        --exclude-per-directory=.gitignore \
        --exclude-from=.git/ignore \
        >output &&
-     git diff expect output'
+     test_cmp expect output'
 
 cat > excludes-file << EOF
 *.[1-8]
diff --git a/t/t3002-ls-files-dashpath.sh b/t/t3002-ls-files-dashpath.sh
index 8687a01d2b..8704b04e1b 100755
--- a/t/t3002-ls-files-dashpath.sh
+++ b/t/t3002-ls-files-dashpath.sh
@@ -23,7 +23,7 @@ test_expect_success \
 test_expect_success \
     'git ls-files without path restriction.' \
     'git ls-files --others >output &&
-     git diff output - <<EOF
+     test_cmp output - <<EOF
 --
 -foo
 output
@@ -34,7 +34,7 @@ EOF
 test_expect_success \
     'git ls-files with path restriction.' \
     'git ls-files --others path0 >output &&
-	git diff output - <<EOF
+	test_cmp output - <<EOF
 path0
 EOF
 '
@@ -42,7 +42,7 @@ EOF
 test_expect_success \
     'git ls-files with path restriction with --.' \
     'git ls-files --others -- path0 >output &&
-	git diff output - <<EOF
+	test_cmp output - <<EOF
 path0
 EOF
 '
@@ -50,7 +50,7 @@ EOF
 test_expect_success \
     'git ls-files with path restriction with -- --.' \
     'git ls-files --others -- -- >output &&
-	git diff output - <<EOF
+	test_cmp output - <<EOF
 --
 EOF
 '
@@ -58,7 +58,7 @@ EOF
 test_expect_success \
     'git ls-files with no path restriction.' \
     'git ls-files --others -- >output &&
-	git diff output - <<EOF
+	test_cmp output - <<EOF
 --
 -foo
 output
diff --git a/t/t3030-merge-recursive.sh b/t/t3030-merge-recursive.sh
index 607f57ff94..aff360303a 100755
--- a/t/t3030-merge-recursive.sh
+++ b/t/t3030-merge-recursive.sh
@@ -43,7 +43,7 @@ test_expect_success 'setup 1' '
 		echo "100644 $o0 0	c"
 		echo "100644 $o1 0	d/e"
 	) >expected &&
-	git diff -u expected actual
+	test_cmp expected actual
 '
 
 test_expect_success 'setup 2' '
@@ -61,7 +61,7 @@ test_expect_success 'setup 2' '
 		echo "100644 $o0 0	c"
 		echo "100644 $o0 0	d/e"
 	) >expected &&
-	git diff -u expected actual &&
+	test_cmp expected actual &&
 
 	echo goodbye >>a &&
 	o2=$(git hash-object a) &&
@@ -82,7 +82,7 @@ test_expect_success 'setup 2' '
 		echo "100644 $o0 0	c"
 		echo "100644 $o0 0	d/e"
 	) >expected &&
-	git diff -u expected actual
+	test_cmp expected actual
 '
 
 test_expect_success 'setup 3' '
@@ -100,7 +100,7 @@ test_expect_success 'setup 3' '
 		echo "100644 $o0 0	c"
 		echo "100644 $o0 0	d/e"
 	) >expected &&
-	git diff -u expected actual &&
+	test_cmp expected actual &&
 
 	rm -f b && mkdir b && echo df-1 >b/c && git add b/c &&
 	o3=$(git hash-object b/c) &&
@@ -119,7 +119,7 @@ test_expect_success 'setup 3' '
 		echo "100644 $o0 0	c"
 		echo "100644 $o0 0	d/e"
 	) >expected &&
-	git diff -u expected actual
+	test_cmp expected actual
 '
 
 test_expect_success 'setup 4' '
@@ -137,7 +137,7 @@ test_expect_success 'setup 4' '
 		echo "100644 $o0 0	c"
 		echo "100644 $o0 0	d/e"
 	) >expected &&
-	git diff -u expected actual &&
+	test_cmp expected actual &&
 
 	rm -f a && mkdir a && echo df-2 >a/c && git add a/c &&
 	o4=$(git hash-object a/c) &&
@@ -156,7 +156,7 @@ test_expect_success 'setup 4' '
 		echo "100644 $o0 0	c"
 		echo "100644 $o0 0	d/e"
 	) >expected &&
-	git diff -u expected actual
+	test_cmp expected actual
 '
 
 test_expect_success 'setup 5' '
@@ -174,7 +174,7 @@ test_expect_success 'setup 5' '
 		echo "100644 $o0 0	c"
 		echo "100644 $o0 0	d/e"
 	) >expected &&
-	git diff -u expected actual &&
+	test_cmp expected actual &&
 
 	rm -f b &&
 	echo remove-conflict >a &&
@@ -195,7 +195,7 @@ test_expect_success 'setup 5' '
 		echo "100644 $o0 0	c"
 		echo "100644 $o0 0	d/e"
 	) >expected &&
-	git diff -u expected actual
+	test_cmp expected actual
 
 '
 
@@ -214,7 +214,7 @@ test_expect_success 'setup 6' '
 		echo "100644 $o0 0	c"
 		echo "100644 $o0 0	d/e"
 	) >expected &&
-	git diff -u expected actual &&
+	test_cmp expected actual &&
 
 	rm -fr d && echo df-3 >d && git add d &&
 	o6=$(git hash-object d) &&
@@ -233,7 +233,7 @@ test_expect_success 'setup 6' '
 		echo "100644 $o0 0	c"
 		echo "100644 $o6 0	d"
 	) >expected &&
-	git diff -u expected actual
+	test_cmp expected actual
 '
 
 test_expect_success 'merge-recursive simple' '
@@ -265,7 +265,7 @@ test_expect_success 'merge-recursive result' '
 		echo "100644 $o0 0	c"
 		echo "100644 $o1 0	d/e"
 	) >expected &&
-	git diff -u expected actual
+	test_cmp expected actual
 
 '
 
@@ -297,7 +297,7 @@ test_expect_success 'merge-recursive remove conflict' '
 		echo "100644 $o0 0	c"
 		echo "100644 $o1 0	d/e"
 	) >expected &&
-	git diff -u expected actual
+	test_cmp expected actual
 
 '
 
@@ -318,7 +318,7 @@ test_expect_success 'merge-recursive result' '
 		echo "100644 $o0 0	c"
 		echo "100644 $o1 0	d/e"
 	) >expected &&
-	git diff -u expected actual
+	test_cmp expected actual
 
 '
 
@@ -352,7 +352,7 @@ test_expect_success 'merge-recursive d/f conflict result' '
 		echo "100644 $o0 0	c"
 		echo "100644 $o1 0	d/e"
 	) >expected &&
-	git diff -u expected actual
+	test_cmp expected actual
 
 '
 
@@ -386,7 +386,7 @@ test_expect_success 'merge-recursive d/f conflict result the other way' '
 		echo "100644 $o0 0	c"
 		echo "100644 $o1 0	d/e"
 	) >expected &&
-	git diff -u expected actual
+	test_cmp expected actual
 
 '
 
@@ -420,7 +420,7 @@ test_expect_success 'merge-recursive d/f conflict result' '
 		echo "100644 $o0 1	d/e"
 		echo "100644 $o1 2	d/e"
 	) >expected &&
-	git diff -u expected actual
+	test_cmp expected actual
 
 '
 
@@ -454,7 +454,7 @@ test_expect_success 'merge-recursive d/f conflict result' '
 		echo "100644 $o0 1	d/e"
 		echo "100644 $o1 3	d/e"
 	) >expected &&
-	git diff -u expected actual
+	test_cmp expected actual
 
 '
 
@@ -480,7 +480,7 @@ test_expect_success 'reset and bind merge' '
 		echo "100644 $o0 0	c"
 		echo "100644 $o1 0	d/e"
 	) >expected &&
-	git diff -u expected actual &&
+	test_cmp expected actual &&
 
 	git read-tree --prefix=a1/ master &&
 	git ls-files -s >actual &&
@@ -498,7 +498,7 @@ test_expect_success 'reset and bind merge' '
 		echo "100644 $o0 0	c"
 		echo "100644 $o1 0	d/e"
 	) >expected &&
-	git diff -u expected actual
+	test_cmp expected actual
 
 	git read-tree --prefix=z/ master &&
 	git ls-files -s >actual &&
@@ -520,7 +520,7 @@ test_expect_success 'reset and bind merge' '
 		echo "100644 $o0 0	z/c"
 		echo "100644 $o1 0	z/d/e"
 	) >expected &&
-	git diff -u expected actual
+	test_cmp expected actual
 
 '
 
diff --git a/t/t3040-subprojects-basic.sh b/t/t3040-subprojects-basic.sh
index 79b9f23654..f6973e96a5 100755
--- a/t/t3040-subprojects-basic.sh
+++ b/t/t3040-subprojects-basic.sh
@@ -24,7 +24,7 @@ test_expect_success 'create subprojects' \
     git add sub2 &&
     git commit -q -m "subprojects added" &&
     git diff-tree --abbrev=5 HEAD^ HEAD |cut -d" " -f-3,5- >current &&
-    git diff expected current'
+    test_cmp expected current'
 
 git branch save HEAD
 
@@ -62,7 +62,7 @@ test_expect_success 'check if clone works' \
     'git ls-files -s >expected &&
     git clone -l -s . cloned &&
     ( cd cloned && git ls-files -s ) >current &&
-    git diff expected current'
+    test_cmp expected current'
 
 test_expect_success 'removing and adding subproject' \
     'git update-index --force-remove -- sub2 &&
diff --git a/t/t3100-ls-tree-restrict.sh b/t/t3100-ls-tree-restrict.sh
index 46427e3f36..6e6a2542a2 100755
--- a/t/t3100-ls-tree-restrict.sh
+++ b/t/t3100-ls-tree-restrict.sh
@@ -35,7 +35,7 @@ _x40='[0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f]'
 _x40="$_x40$_x40$_x40$_x40$_x40$_x40$_x40$_x40"
 test_output () {
     sed -e "s/ $_x40	/ X	/" <current >check
-    git diff expected check
+    test_cmp expected check
 }
 
 test_expect_success \
diff --git a/t/t3101-ls-tree-dirname.sh b/t/t3101-ls-tree-dirname.sh
index 70f9ce9d52..4dd7d12bac 100755
--- a/t/t3101-ls-tree-dirname.sh
+++ b/t/t3101-ls-tree-dirname.sh
@@ -43,7 +43,7 @@ _x40='[0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f]'
 _x40="$_x40$_x40$_x40$_x40$_x40$_x40$_x40$_x40"
 test_output () {
     sed -e "s/ $_x40	/ X	/" <current >check
-    git diff expected check
+    test_cmp expected check
 }
 
 test_expect_success \
diff --git a/t/t3300-funny-names.sh b/t/t3300-funny-names.sh
index 24a00a9df1..0574ef1f10 100755
--- a/t/t3300-funny-names.sh
+++ b/t/t3300-funny-names.sh
@@ -35,7 +35,7 @@ no-funny' >expected
 test_expect_success 'git ls-files no-funny' \
 	'git update-index --add "$p0" "$p2" &&
 	git ls-files >current &&
-	git diff expected current'
+	test_cmp expected current'
 
 t0=`git write-tree`
 echo "$t0" >t0
@@ -48,14 +48,14 @@ EOF
 test_expect_success 'git ls-files with-funny' \
 	'git update-index --add "$p1" &&
 	git ls-files >current &&
-	git diff expected current'
+	test_cmp expected current'
 
 echo 'just space
 no-funny
 tabs	," (dq) and spaces' >expected
 test_expect_success 'git ls-files -z with-funny' \
 	'git ls-files -z | perl -pe y/\\000/\\012/ >current &&
-	git diff expected current'
+	test_cmp expected current'
 
 t1=`git write-tree`
 echo "$t1" >t1
@@ -67,28 +67,28 @@ no-funny
 EOF
 test_expect_success 'git ls-tree with funny' \
 	'git ls-tree -r $t1 | sed -e "s/^[^	]*	//" >current &&
-	 git diff expected current'
+	 test_cmp expected current'
 
 cat > expected <<\EOF
 A	"tabs\t,\" (dq) and spaces"
 EOF
 test_expect_success 'git diff-index with-funny' \
 	'git diff-index --name-status $t0 >current &&
-	git diff expected current'
+	test_cmp expected current'
 
 test_expect_success 'git diff-tree with-funny' \
 	'git diff-tree --name-status $t0 $t1 >current &&
-	git diff expected current'
+	test_cmp expected current'
 
 echo 'A
 tabs	," (dq) and spaces' >expected
 test_expect_success 'git diff-index -z with-funny' \
 	'git diff-index -z --name-status $t0 | perl -pe y/\\000/\\012/ >current &&
-	git diff expected current'
+	test_cmp expected current'
 
 test_expect_success 'git diff-tree -z with-funny' \
 	'git diff-tree -z --name-status $t0 $t1 | perl -pe y/\\000/\\012/ >current &&
-	git diff expected current'
+	test_cmp expected current'
 
 cat > expected <<\EOF
 CNUM	no-funny	"tabs\t,\" (dq) and spaces"
@@ -96,7 +96,7 @@ EOF
 test_expect_success 'git diff-tree -C with-funny' \
 	'git diff-tree -C --find-copies-harder --name-status \
 		$t0 $t1 | sed -e 's/^C[0-9]*/CNUM/' >current &&
-	git diff expected current'
+	test_cmp expected current'
 
 cat > expected <<\EOF
 RNUM	no-funny	"tabs\t,\" (dq) and spaces"
@@ -105,7 +105,7 @@ test_expect_success 'git diff-tree delete with-funny' \
 	'git update-index --force-remove "$p0" &&
 	git diff-index -M --name-status \
 		$t0 | sed -e 's/^R[0-9]*/RNUM/' >current &&
-	git diff expected current'
+	test_cmp expected current'
 
 cat > expected <<\EOF
 diff --git a/no-funny "b/tabs\t,\" (dq) and spaces"
@@ -116,7 +116,7 @@ EOF
 test_expect_success 'git diff-tree delete with-funny' \
 	'git diff-index -M -p $t0 |
 	 sed -e "s/index [0-9]*%/index NUM%/" >current &&
-	 git diff expected current'
+	 test_cmp expected current'
 
 chmod +x "$p1"
 cat > expected <<\EOF
@@ -130,7 +130,7 @@ EOF
 test_expect_success 'git diff-tree delete with-funny' \
 	'git diff-index -M -p $t0 |
 	 sed -e "s/index [0-9]*%/index NUM%/" >current &&
-	 git diff expected current'
+	 test_cmp expected current'
 
 cat >expected <<\EOF
  "tabs\t,\" (dq) and spaces"
@@ -139,7 +139,7 @@ EOF
 test_expect_success 'git diff-tree rename with-funny applied' \
 	'git diff-index -M -p $t0 |
 	 git apply --stat | sed -e "s/|.*//" -e "s/ *\$//" >current &&
-	 git diff expected current'
+	 test_cmp expected current'
 
 cat > expected <<\EOF
  no-funny
@@ -149,12 +149,12 @@ EOF
 test_expect_success 'git diff-tree delete with-funny applied' \
 	'git diff-index -p $t0 |
 	 git apply --stat | sed -e "s/|.*//" -e "s/ *\$//" >current &&
-	 git diff expected current'
+	 test_cmp expected current'
 
 test_expect_success 'git apply non-git diff' \
 	'git diff-index -p $t0 |
 	 sed -ne "/^[-+@]/p" |
 	 git apply --stat | sed -e "s/|.*//" -e "s/ *\$//" >current &&
-	 git diff expected current'
+	 test_cmp expected current'
 
 test_done
diff --git a/t/t3900-i18n-commit.sh b/t/t3900-i18n-commit.sh
index 94b1c24b0a..883281dbd6 100755
--- a/t/t3900-i18n-commit.sh
+++ b/t/t3900-i18n-commit.sh
@@ -9,7 +9,7 @@ test_description='commit and log output encodings'
 
 compare_with () {
 	git show -s $1 | sed -e '1,/^$/d' -e 's/^    //' >current &&
-	git diff current "$2"
+	test_cmp current "$2"
 }
 
 test_expect_success setup '
diff --git a/t/t4006-diff-mode.sh b/t/t4006-diff-mode.sh
index ab5406dd9f..4e92fce1d0 100755
--- a/t/t4006-diff-mode.sh
+++ b/t/t4006-diff-mode.sh
@@ -38,6 +38,6 @@ echo ":100644 100755 X X M	rezrov" >expected
 
 test_expect_success \
     'verify' \
-    'git diff expected check'
+    'test_cmp expected check'
 
 test_done
diff --git a/t/t4013-diff-various.sh b/t/t4013-diff-various.sh
index 6b4d1c52bb..9337b81064 100755
--- a/t/t4013-diff-various.sh
+++ b/t/t4013-diff-various.sh
@@ -112,7 +112,7 @@ do
 		} >"$actual" &&
 		if test -f "$expect"
 		then
-			git diff "$expect" "$actual" &&
+			test_cmp "$expect" "$actual" &&
 			rm -f "$actual"
 		else
 			# this is to help developing new tests.
@@ -257,6 +257,7 @@ diff --patch-with-raw initial..side
 diff --patch-with-stat -r initial..side
 diff --patch-with-raw -r initial..side
 diff --name-status dir2 dir
+diff --no-index --name-status dir2 dir
 EOF
 
 test_done
diff --git a/t/t4013/diff.diff_--name-status_dir2_dir b/t/t4013/diff.diff_--name-status_dir2_dir
index ef7fdb7335..d0d96aaa91 100644
--- a/t/t4013/diff.diff_--name-status_dir2_dir
+++ b/t/t4013/diff.diff_--name-status_dir2_dir
@@ -1,3 +1,2 @@
 $ git diff --name-status dir2 dir
-A	dir/sub
 $
diff --git a/t/t4013/diff.diff_--no-index_--name-status_dir2_dir b/t/t4013/diff.diff_--no-index_--name-status_dir2_dir
new file mode 100644
index 0000000000..6a47584777
--- /dev/null
+++ b/t/t4013/diff.diff_--no-index_--name-status_dir2_dir
@@ -0,0 +1,3 @@
+$ git diff --no-index --name-status dir2 dir
+A	dir/sub
+$
diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
index b2b7a8db85..3583e68e92 100755
--- a/t/t4014-format-patch.sh
+++ b/t/t4014-format-patch.sh
@@ -226,7 +226,7 @@ test_expect_success 'shortlog of cover-letter wraps overly-long onelines' '
 
 	git format-patch --cover-letter -2 &&
 	sed -e "1,/A U Thor/d" -e "/^$/q" < 0000-cover-letter.patch > output &&
-	git diff expect output
+	test_cmp expect output
 
 '
 
diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index 83c54b747f..ca0302f41b 100755
--- a/t/t4015-diff-whitespace.sh
+++ b/t/t4015-diff-whitespace.sh
@@ -43,13 +43,13 @@ index adf3937..6edc172 100644
 EOF
 
 git diff > out
-test_expect_success "Ray's example without options" 'git diff expect out'
+test_expect_success "Ray's example without options" 'test_cmp expect out'
 
 git diff -w > out
-test_expect_success "Ray's example with -w" 'git diff expect out'
+test_expect_success "Ray's example with -w" 'test_cmp expect out'
 
 git diff -b > out
-test_expect_success "Ray's example with -b" 'git diff expect out'
+test_expect_success "Ray's example with -b" 'test_cmp expect out'
 
 tr 'Q' '\015' << EOF > x
 whitespace at beginning
@@ -90,14 +90,14 @@ index d99af23..8b32fb5 100644
 +CR at end
 EOF
 git diff > out
-test_expect_success 'another test, without options' 'git diff expect out'
+test_expect_success 'another test, without options' 'test_cmp expect out'
 
 cat << EOF > expect
 diff --git a/x b/x
 index d99af23..8b32fb5 100644
 EOF
 git diff -w > out
-test_expect_success 'another test, with -w' 'git diff expect out'
+test_expect_success 'another test, with -w' 'test_cmp expect out'
 
 tr 'Q' '\015' << EOF > expect
 diff --git a/x b/x
@@ -115,7 +115,7 @@ index d99af23..8b32fb5 100644
  CR at endQ
 EOF
 git diff -b > out
-test_expect_success 'another test, with -b' 'git diff expect out'
+test_expect_success 'another test, with -b' 'test_cmp expect out'
 
 test_expect_success 'check mixed spaces and tabs in indent' '
 
diff --git a/t/t4016-diff-quote.sh b/t/t4016-diff-quote.sh
index 5dbdc0c9fa..0950250c9b 100755
--- a/t/t4016-diff-quote.sh
+++ b/t/t4016-diff-quote.sh
@@ -49,7 +49,7 @@ cat >expect <<\EOF
 EOF
 test_expect_success 'git diff --summary -M HEAD' '
 	git diff --summary -M HEAD >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 cat >expect <<\EOF
@@ -64,7 +64,7 @@ cat >expect <<\EOF
 EOF
 test_expect_success 'git diff --stat -M HEAD' '
 	git diff --stat -M HEAD >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 test_done
diff --git a/t/t4018-diff-funcname.sh b/t/t4018-diff-funcname.sh
index f9db81d3ab..6d3ef6c60b 100755
--- a/t/t4018-diff-funcname.sh
+++ b/t/t4018-diff-funcname.sh
@@ -33,13 +33,13 @@ EOF
 sed 's/beer\\/beer,\\/' < Beer.java > Beer-correct.java
 
 test_expect_success 'default behaviour' '
-	git diff Beer.java Beer-correct.java |
+	git diff --no-index Beer.java Beer-correct.java |
 	grep "^@@.*@@ public class Beer"
 '
 
 test_expect_success 'preset java pattern' '
 	echo "*.java diff=java" >.gitattributes &&
-	git diff Beer.java Beer-correct.java |
+	git diff --no-index Beer.java Beer-correct.java |
 	grep "^@@.*@@ public static void main("
 '
 
@@ -48,13 +48,13 @@ git config diff.java.funcname '!static
 [^ 	].*s.*'
 
 test_expect_success 'custom pattern' '
-	git diff Beer.java Beer-correct.java |
+	git diff --no-index Beer.java Beer-correct.java |
 	grep "^@@.*@@ int special;$"
 '
 
 test_expect_success 'last regexp must not be negated' '
 	git config diff.java.funcname "!static" &&
-	! git diff Beer.java Beer-correct.java
+	! git diff --no-index Beer.java Beer-correct.java
 '
 
 test_done
diff --git a/t/t4100-apply-stat.sh b/t/t4100-apply-stat.sh
index 435f65b370..8073a5a1f2 100755
--- a/t/t4100-apply-stat.sh
+++ b/t/t4100-apply-stat.sh
@@ -11,36 +11,36 @@ test_description='git apply --stat --summary test.
 test_expect_success \
     'rename' \
     'git apply --stat --summary <../t4100/t-apply-1.patch >current &&
-    git diff ../t4100/t-apply-1.expect current'
+    test_cmp ../t4100/t-apply-1.expect current'
 
 test_expect_success \
     'copy' \
     'git apply --stat --summary <../t4100/t-apply-2.patch >current &&
-    git diff ../t4100/t-apply-2.expect current'
+    test_cmp ../t4100/t-apply-2.expect current'
 
 test_expect_success \
     'rewrite' \
     'git apply --stat --summary <../t4100/t-apply-3.patch >current &&
-    git diff ../t4100/t-apply-3.expect current'
+    test_cmp ../t4100/t-apply-3.expect current'
 
 test_expect_success \
     'mode' \
     'git apply --stat --summary <../t4100/t-apply-4.patch >current &&
-    git diff ../t4100/t-apply-4.expect current'
+    test_cmp ../t4100/t-apply-4.expect current'
 
 test_expect_success \
     'non git' \
     'git apply --stat --summary <../t4100/t-apply-5.patch >current &&
-    git diff ../t4100/t-apply-5.expect current'
+    test_cmp ../t4100/t-apply-5.expect current'
 
 test_expect_success \
     'non git' \
     'git apply --stat --summary <../t4100/t-apply-6.patch >current &&
-    git diff ../t4100/t-apply-6.expect current'
+    test_cmp ../t4100/t-apply-6.expect current'
 
 test_expect_success \
     'non git' \
     'git apply --stat --summary <../t4100/t-apply-7.patch >current &&
-    git diff ../t4100/t-apply-7.expect current'
+    test_cmp ../t4100/t-apply-7.expect current'
 
 test_done
diff --git a/t/t4104-apply-boundary.sh b/t/t4104-apply-boundary.sh
index 43943ab8ca..e7e2913de7 100755
--- a/t/t4104-apply-boundary.sh
+++ b/t/t4104-apply-boundary.sh
@@ -90,7 +90,7 @@ do
 				cat '"$kind-patch.$with"'
 				(exit 1)
 			} &&
-			git diff '"$kind"'-expect victim
+			test_cmp '"$kind"'-expect victim
 		'
 	done
 done
@@ -108,7 +108,7 @@ do
 			cat '"$kind-ng.without"'
 			(exit 1)
 		} &&
-		git diff '"$kind"'-expect victim
+		test_cmp '"$kind"'-expect victim
 	'
 done
 
diff --git a/t/t4115-apply-symlink.sh b/t/t4115-apply-symlink.sh
index a07ff42c2f..9ace578f17 100755
--- a/t/t4115-apply-symlink.sh
+++ b/t/t4115-apply-symlink.sh
@@ -33,7 +33,7 @@ test_expect_success 'apply symlink patch' '
 	git checkout side &&
 	git apply patch &&
 	git diff-files -p >patched &&
-	git diff patch patched
+	test_cmp patch patched
 
 '
 
@@ -42,7 +42,7 @@ test_expect_success 'apply --index symlink patch' '
 	git checkout -f side &&
 	git apply --index patch &&
 	git diff-index --cached -p HEAD >patched &&
-	git diff patch patched
+	test_cmp patch patched
 
 '
 
diff --git a/t/t4116-apply-reverse.sh b/t/t4116-apply-reverse.sh
index c3f4579007..1459a90716 100755
--- a/t/t4116-apply-reverse.sh
+++ b/t/t4116-apply-reverse.sh
@@ -42,7 +42,7 @@ test_expect_success 'apply in reverse' '
 	git reset --hard second &&
 	git apply --reverse --binary --index patch &&
 	git diff >diff &&
-	git diff /dev/null diff
+	test_cmp /dev/null diff
 
 '
 
diff --git a/t/t4117-apply-reject.sh b/t/t4117-apply-reject.sh
index 659e17c92e..e9ccd161ee 100755
--- a/t/t4117-apply-reject.sh
+++ b/t/t4117-apply-reject.sh
@@ -54,7 +54,7 @@ test_expect_success 'apply without --reject should fail' '
 		exit 1
 	fi
 
-	git diff file1 saved.file1
+	test_cmp file1 saved.file1
 '
 
 test_expect_success 'apply without --reject should fail' '
@@ -65,7 +65,7 @@ test_expect_success 'apply without --reject should fail' '
 		exit 1
 	fi
 
-	git diff file1 saved.file1
+	test_cmp file1 saved.file1
 '
 
 test_expect_success 'apply with --reject should fail but update the file' '
@@ -79,7 +79,7 @@ test_expect_success 'apply with --reject should fail but update the file' '
 		exit 1
 	fi
 
-	git diff file1 expected &&
+	test_cmp file1 expected &&
 
 	cat file1.rej &&
 
@@ -105,7 +105,7 @@ test_expect_success 'apply with --reject should fail but update the file' '
 		echo "file1 still exists?"
 		exit 1
 	}
-	git diff file2 expected &&
+	test_cmp file2 expected &&
 
 	cat file2.rej &&
 
@@ -132,7 +132,7 @@ test_expect_success 'the same test with --verbose' '
 		echo "file1 still exists?"
 		exit 1
 	}
-	git diff file2 expected &&
+	test_cmp file2 expected &&
 
 	cat file2.rej &&
 
@@ -151,7 +151,7 @@ test_expect_success 'apply cleanly with --verbose' '
 
 	git apply --verbose patch.1 &&
 
-	git diff file1 clean
+	test_cmp file1 clean
 '
 
 test_done
diff --git a/t/t4118-apply-empty-context.sh b/t/t4118-apply-empty-context.sh
index 1d531caf79..f92e259cc6 100755
--- a/t/t4118-apply-empty-context.sh
+++ b/t/t4118-apply-empty-context.sh
@@ -38,7 +38,7 @@ test_expect_success 'apply --numstat' '
 		echo "0	1	file1" &&
 		echo "0	1	file2"
 	} >expect &&
-	git diff expect actual
+	test_cmp expect actual
 
 '
 
@@ -48,8 +48,8 @@ test_expect_success 'apply --apply' '
 	cat file2.orig >file2 &&
 	git update-index file1 file2 &&
 	git apply --index diff.output &&
-	git diff file1.mods file1 &&
-	git diff file2.mods file2
+	test_cmp file1.mods file1 &&
+	test_cmp file2.mods file2
 '
 
 test_done
diff --git a/t/t4200-rerere.sh b/t/t4200-rerere.sh
index 3cbfee704e..85d7e3edcd 100755
--- a/t/t4200-rerere.sh
+++ b/t/t4200-rerere.sh
@@ -101,7 +101,7 @@ cat > expect << EOF
 EOF
 git rerere diff > out
 
-test_expect_success 'rerere diff' 'git diff expect out'
+test_expect_success 'rerere diff' 'test_cmp expect out'
 
 cat > expect << EOF
 a1
@@ -109,7 +109,7 @@ EOF
 
 git rerere status > out
 
-test_expect_success 'rerere status' 'git diff expect out'
+test_expect_success 'rerere status' 'test_cmp expect out'
 
 test_expect_success 'commit succeeds' \
 	"git commit -q -a -m 'prefer first over second'"
@@ -126,7 +126,7 @@ test_expect_success 'another conflicting merge' '
 git show first:a1 | sed 's/To die: t/To die! T/' > expect
 test_expect_success 'rerere kicked in' "! grep ======= a1"
 
-test_expect_success 'rerere prefers first change' 'git diff a1 expect'
+test_expect_success 'rerere prefers first change' 'test_cmp a1 expect'
 
 rm $rr/postimage
 echo "$sha1	a1" | perl -pe 'y/\012/\000/' > .git/rr-cache/MERGE_RR
diff --git a/t/t5305-include-tag.sh b/t/t5305-include-tag.sh
index 0db27547ac..fb471a08c6 100755
--- a/t/t5305-include-tag.sh
+++ b/t/t5305-include-tag.sh
@@ -50,7 +50,7 @@ test_expect_success 'check unpacked result (have commit, no tag)' '
 		test_must_fail git cat-file -e $tag &&
 		git rev-list --objects $commit
 	) >list.actual &&
-	git diff list.expect list.actual
+	test_cmp list.expect list.actual
 '
 
 rm -rf clone.git
@@ -78,7 +78,7 @@ test_expect_success 'check unpacked result (have commit, have tag)' '
 		export GIT_DIR &&
 		git rev-list --objects $tag
 	) >list.actual &&
-	git diff list.expect list.actual
+	test_cmp list.expect list.actual
 '
 
 test_done
diff --git a/t/t5400-send-pack.sh b/t/t5400-send-pack.sh
index 2b6b6e3f71..68c2ae688c 100755
--- a/t/t5400-send-pack.sh
+++ b/t/t5400-send-pack.sh
@@ -110,7 +110,7 @@ test_expect_success \
 	cd .. &&
 	git update-ref refs/heads/master master^ || return 1
 	git-send-pack --force ./victim/.git/ master && return 1
-	! git diff .git/refs/heads/master victim/.git/refs/heads/master
+	! test_cmp .git/refs/heads/master victim/.git/refs/heads/master
 '
 
 test_expect_success \
diff --git a/t/t5401-update-hooks.sh b/t/t5401-update-hooks.sh
index 9a12024241..2fff300153 100755
--- a/t/t5401-update-hooks.sh
+++ b/t/t5401-update-hooks.sh
@@ -83,23 +83,23 @@ test_expect_success 'hooks ran' '
 test_expect_success 'pre-receive hook input' '
 	(echo $commit0 $commit1 refs/heads/master;
 	 echo $commit1 $commit0 refs/heads/tofail
-	) | git diff - victim/.git/pre-receive.stdin
+	) | test_cmp - victim/.git/pre-receive.stdin
 '
 
 test_expect_success 'update hook arguments' '
 	(echo refs/heads/master $commit0 $commit1;
 	 echo refs/heads/tofail $commit1 $commit0
-	) | git diff - victim/.git/update.args
+	) | test_cmp - victim/.git/update.args
 '
 
 test_expect_success 'post-receive hook input' '
 	echo $commit0 $commit1 refs/heads/master |
-	git diff - victim/.git/post-receive.stdin
+	test_cmp - victim/.git/post-receive.stdin
 '
 
 test_expect_success 'post-update hook arguments' '
 	echo refs/heads/master |
-	git diff - victim/.git/post-update.args
+	test_cmp - victim/.git/post-update.args
 '
 
 test_expect_success 'all hook stdin is /dev/null' '
@@ -130,7 +130,7 @@ STDERR post-update
 EOF
 test_expect_success 'send-pack stderr contains hook messages' '
 	grep ^STD send.err >actual &&
-	git diff - actual <expect
+	test_cmp - actual <expect
 '
 
 test_done
diff --git a/t/t5503-tagfollow.sh b/t/t5503-tagfollow.sh
index 86e5b9bc26..4074e23ffa 100755
--- a/t/t5503-tagfollow.sh
+++ b/t/t5503-tagfollow.sh
@@ -50,7 +50,7 @@ test_expect_success 'fetch A (new commit : 1 connection)' '
 	) &&
 	test -s $U &&
 	cut -d" " -f1,2 $U >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 test_expect_success "create tag T on A, create C on branch cat" '
@@ -82,7 +82,7 @@ test_expect_success 'fetch C, T (new branch, tag : 1 connection)' '
 	) &&
 	test -s $U &&
 	cut -d" " -f1,2 $U >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 test_expect_success "create commits O, B, tag S on B" '
@@ -118,7 +118,7 @@ test_expect_success 'fetch B, S (commit and tag : 1 connection)' '
 	) &&
 	test -s $U &&
 	cut -d" " -f1,2 $U >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 cat - <<EOF >expect
@@ -144,7 +144,7 @@ test_expect_success 'new clone fetch master and tags' '
 	) &&
 	test -s $U &&
 	cut -d" " -f1,2 $U >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 test_done
diff --git a/t/t5505-remote.sh b/t/t5505-remote.sh
index 48ff2d424d..a37b6f5213 100755
--- a/t/t5505-remote.sh
+++ b/t/t5505-remote.sh
@@ -135,7 +135,7 @@ test_expect_success 'show' '
 	 git config --add remote.origin.push \
 		+refs/tags/lastbackup &&
 	 git remote show origin > output &&
-	 git diff expect output)
+	 test_cmp expect output)
 '
 
 test_expect_success 'prune' '
@@ -179,7 +179,7 @@ test_expect_success 'update' '
 	 git remote add apis ../mirror &&
 	 git remote update &&
 	 git branch -r > output &&
-	 git diff expect output)
+	 test_cmp expect output)
 
 '
 
@@ -206,7 +206,7 @@ test_expect_success 'update with arguments' '
 	 git config remotes.titanus manduca &&
 	 git remote update phobaeticus titanus &&
 	 git branch -r > output &&
-	 git diff expect output)
+	 test_cmp expect output)
 
 '
 
@@ -229,7 +229,7 @@ test_expect_success 'update default' '
 	 git config remote.drosophila.skipDefaultUpdate true &&
 	 git remote update default &&
 	 git branch -r > output &&
-	 git diff expect output)
+	 test_cmp expect output)
 
 '
 
@@ -249,7 +249,7 @@ test_expect_success 'update default (overridden, with funny whitespace)' '
 	 git config remotes.default "$(printf "\t drosophila  \n")" &&
 	 git remote update default &&
 	 git branch -r > output &&
-	 git diff expect output)
+	 test_cmp expect output)
 
 '
 
diff --git a/t/t5515-fetch-merge-logic.sh b/t/t5515-fetch-merge-logic.sh
index 65c37744aa..3def75eeb2 100755
--- a/t/t5515-fetch-merge-logic.sh
+++ b/t/t5515-fetch-merge-logic.sh
@@ -151,7 +151,7 @@ do
 		git show-ref >"$actual_r" &&
 		if test -f "$expect_f"
 		then
-			git diff -u "$expect_f" "$actual_f" &&
+			test_cmp "$expect_f" "$actual_f" &&
 			rm -f "$actual_f"
 		else
 			# this is to help developing new tests.
@@ -160,7 +160,7 @@ do
 		fi &&
 		if test -f "$expect_r"
 		then
-			git diff -u "$expect_r" "$actual_r" &&
+			test_cmp "$expect_r" "$actual_r" &&
 			rm -f "$actual_r"
 		else
 			# this is to help developing new tests.
diff --git a/t/t6006-rev-list-format.sh b/t/t6006-rev-list-format.sh
index 0dc915ea67..9176484db2 100755
--- a/t/t6006-rev-list-format.sh
+++ b/t/t6006-rev-list-format.sh
@@ -15,7 +15,7 @@ test_format() {
 	cat >expect.$1
 	test_expect_success "format $1" "
 git rev-list --pretty=format:$2 master >output.$1 &&
-git diff expect.$1 output.$1
+test_cmp expect.$1 output.$1
 "
 }
 
diff --git a/t/t6023-merge-file.sh b/t/t6023-merge-file.sh
index 79dc58b2ce..74e9e6618e 100755
--- a/t/t6023-merge-file.sh
+++ b/t/t6023-merge-file.sh
@@ -63,7 +63,7 @@ test_expect_success "merge without conflict (missing LF at EOF)" \
 	"git merge-file test2.txt orig.txt new2.txt"
 
 test_expect_success "merge result added missing LF" \
-	"git diff test.txt test2.txt"
+	"test_cmp test.txt test2.txt"
 
 cp test.txt backup.txt
 test_expect_success "merge with conflicts" \
@@ -86,7 +86,7 @@ non timebo mala, quoniam tu mecum es:
 virga tua et baculus tuus ipsa me consolata sunt.
 EOF
 
-test_expect_success "expected conflict markers" "git diff test.txt expect.txt"
+test_expect_success "expected conflict markers" "test_cmp test.txt expect.txt"
 
 cp backup.txt test.txt
 test_expect_success "merge with conflicts, using -L" \
@@ -110,7 +110,7 @@ virga tua et baculus tuus ipsa me consolata sunt.
 EOF
 
 test_expect_success "expected conflict markers, with -L" \
-	"git diff test.txt expect.txt"
+	"test_cmp test.txt expect.txt"
 
 sed "s/ tu / TU /" < new1.txt > new5.txt
 test_expect_success "conflict in removed tail" \
@@ -132,7 +132,7 @@ virga tua et baculus tuus ipsa me consolata sunt.
 >>>>>>> new5.txt
 EOF
 
-test_expect_success "expected conflict markers" "git diff expect out"
+test_expect_success "expected conflict markers" "test_cmp expect out"
 
 test_expect_success 'binary files cannot be merged' '
 	! git merge-file -p orig.txt ../test4012.png new1.txt 2> merge.err &&
diff --git a/t/t6024-recursive-merge.sh b/t/t6024-recursive-merge.sh
index 23d24d3feb..6a6a13002d 100755
--- a/t/t6024-recursive-merge.sh
+++ b/t/t6024-recursive-merge.sh
@@ -70,7 +70,7 @@ G
 >>>>>>> G:a1
 EOF
 
-test_expect_success "result contains a conflict" "git diff expect a1"
+test_expect_success "result contains a conflict" "test_cmp expect a1"
 
 git ls-files --stage > out
 cat > expect << EOF
@@ -79,7 +79,7 @@ cat > expect << EOF
 100644 fd7923529855d0b274795ae3349c5e0438333979 3	a1
 EOF
 
-test_expect_success "virtual trees were processed" "git diff expect out"
+test_expect_success "virtual trees were processed" "test_cmp expect out"
 
 test_expect_success 'refuse to merge binary files' '
 	git reset --hard &&
diff --git a/t/t6029-merge-subtree.sh b/t/t6029-merge-subtree.sh
index 43f5459c35..5bbfa44e8d 100755
--- a/t/t6029-merge-subtree.sh
+++ b/t/t6029-merge-subtree.sh
@@ -57,7 +57,7 @@ test_expect_success 'initial merge' '
 		echo "100644 $o1 0	git-gui/git-gui.sh"
 		echo "100644 $o2 0	git.c"
 	) >expected &&
-	git diff -u expected actual
+	test_cmp expected actual
 '
 
 test_expect_success 'merge update' '
@@ -73,7 +73,7 @@ test_expect_success 'merge update' '
 		echo "100644 $o3 0	git-gui/git-gui.sh"
 		echo "100644 $o2 0	git.c"
 	) >expected &&
-	git diff -u expected actual
+	test_cmp expected actual
 '
 
 test_done
diff --git a/t/t6120-describe.sh b/t/t6120-describe.sh
index 56bbd8519d..ea476a2582 100755
--- a/t/t6120-describe.sh
+++ b/t/t6120-describe.sh
@@ -108,7 +108,7 @@ warning: tag 'A' is really 'Q' here
 EOF
 check_describe A-* HEAD
 test_expect_success 'warning was displayed for Q' '
-	git diff err.expect err.actual
+	test_cmp err.expect err.actual
 '
 test_expect_success 'rename tag Q back to A' '
 	mv .git/refs/tags/Q .git/refs/tags/A
diff --git a/t/t6200-fmt-merge-msg.sh b/t/t6200-fmt-merge-msg.sh
index c9bf6fdba3..bc74349416 100755
--- a/t/t6200-fmt-merge-msg.sh
+++ b/t/t6200-fmt-merge-msg.sh
@@ -79,7 +79,7 @@ test_expect_success 'merge-msg test #1' '
 	git fetch . left &&
 
 	git fmt-merge-msg <.git/FETCH_HEAD >actual &&
-	git diff actual expected
+	test_cmp expected actual
 '
 
 cat >expected <<EOF
@@ -92,7 +92,7 @@ test_expect_success 'merge-msg test #2' '
 	git fetch ../"$test" left &&
 
 	git fmt-merge-msg <.git/FETCH_HEAD >actual &&
-	git diff actual expected
+	test_cmp expected actual
 '
 
 cat >expected <<\EOF
@@ -117,7 +117,7 @@ test_expect_success 'merge-msg test #3-1' '
 	git fetch . left &&
 
 	git fmt-merge-msg <.git/FETCH_HEAD >actual &&
-	git diff actual expected
+	test_cmp expected actual
 '
 
 test_expect_success 'merge-msg test #3-2' '
@@ -131,7 +131,7 @@ test_expect_success 'merge-msg test #3-2' '
 	git fetch . left &&
 
 	git fmt-merge-msg <.git/FETCH_HEAD >actual &&
-	git diff actual expected
+	test_cmp expected actual
 '
 
 cat >expected <<\EOF
@@ -163,7 +163,7 @@ test_expect_success 'merge-msg test #4-1' '
 	git fetch . left right &&
 
 	git fmt-merge-msg <.git/FETCH_HEAD >actual &&
-	git diff actual expected
+	test_cmp expected actual
 '
 
 test_expect_success 'merge-msg test #4-2' '
@@ -177,7 +177,7 @@ test_expect_success 'merge-msg test #4-2' '
 	git fetch . left right &&
 
 	git fmt-merge-msg <.git/FETCH_HEAD >actual &&
-	git diff actual expected
+	test_cmp expected actual
 '
 
 test_expect_success 'merge-msg test #5-1' '
@@ -191,7 +191,7 @@ test_expect_success 'merge-msg test #5-1' '
 	git fetch . left right &&
 
 	git fmt-merge-msg <.git/FETCH_HEAD >actual &&
-	git diff actual expected
+	test_cmp expected actual
 '
 
 test_expect_success 'merge-msg test #5-2' '
@@ -205,7 +205,7 @@ test_expect_success 'merge-msg test #5-2' '
 	git fetch . left right &&
 
 	git fmt-merge-msg <.git/FETCH_HEAD >actual &&
-	git diff actual expected
+	test_cmp expected actual
 '
 
 test_done
diff --git a/t/t6300-for-each-ref.sh b/t/t6300-for-each-ref.sh
index f46ec93c83..91ea85d99b 100755
--- a/t/t6300-for-each-ref.sh
+++ b/t/t6300-for-each-ref.sh
@@ -75,14 +75,14 @@ EOF
 test_expect_success 'Check unformatted date fields output' '
 	(git for-each-ref --shell --format="%(refname) %(committerdate) %(authordate)" refs/heads &&
 	git for-each-ref --shell --format="%(refname) %(taggerdate)" refs/tags) >actual &&
-	git diff expected actual
+	test_cmp expected actual
 '
 
 test_expect_success 'Check format "default" formatted date fields output' '
 	f=default &&
 	(git for-each-ref --shell --format="%(refname) %(committerdate:$f) %(authordate:$f)" refs/heads &&
 	git for-each-ref --shell --format="%(refname) %(taggerdate:$f)" refs/tags) >actual &&
-	git diff expected actual
+	test_cmp expected actual
 '
 
 # Don't know how to do relative check because I can't know when this script
@@ -109,7 +109,7 @@ test_expect_success 'Check format "short" date fields output' '
 	f=short &&
 	(git for-each-ref --shell --format="%(refname) %(committerdate:$f) %(authordate:$f)" refs/heads &&
 	git for-each-ref --shell --format="%(refname) %(taggerdate:$f)" refs/tags) >actual &&
-	git diff expected actual
+	test_cmp expected actual
 '
 
 cat >expected <<\EOF
@@ -121,7 +121,7 @@ test_expect_success 'Check format "local" date fields output' '
 	f=local &&
 	(git for-each-ref --shell --format="%(refname) %(committerdate:$f) %(authordate:$f)" refs/heads &&
 	git for-each-ref --shell --format="%(refname) %(taggerdate:$f)" refs/tags) >actual &&
-	git diff expected actual
+	test_cmp expected actual
 '
 
 cat >expected <<\EOF
@@ -133,7 +133,7 @@ test_expect_success 'Check format "iso8601" date fields output' '
 	f=iso8601 &&
 	(git for-each-ref --shell --format="%(refname) %(committerdate:$f) %(authordate:$f)" refs/heads &&
 	git for-each-ref --shell --format="%(refname) %(taggerdate:$f)" refs/tags) >actual &&
-	git diff expected actual
+	test_cmp expected actual
 '
 
 cat >expected <<\EOF
@@ -145,7 +145,7 @@ test_expect_success 'Check format "rfc2822" date fields output' '
 	f=rfc2822 &&
 	(git for-each-ref --shell --format="%(refname) %(committerdate:$f) %(authordate:$f)" refs/heads &&
 	git for-each-ref --shell --format="%(refname) %(taggerdate:$f)" refs/tags) >actual &&
-	git diff expected actual
+	test_cmp expected actual
 '
 
 cat >expected <<\EOF
@@ -155,7 +155,7 @@ EOF
 
 test_expect_success 'Verify ascending sort' '
 	git-for-each-ref --format="%(refname)" --sort=refname >actual &&
-	git diff expected actual
+	test_cmp expected actual
 '
 
 
@@ -166,7 +166,7 @@ EOF
 
 test_expect_success 'Verify descending sort' '
 	git-for-each-ref --format="%(refname)" --sort=-refname >actual &&
-	git diff expected actual
+	test_cmp expected actual
 '
 
 cat >expected <<\EOF
@@ -176,17 +176,17 @@ EOF
 
 test_expect_success 'Quoting style: shell' '
 	git for-each-ref --shell --format="%(refname)" >actual &&
-	git diff expected actual
+	test_cmp expected actual
 '
 
 test_expect_success 'Quoting style: perl' '
 	git for-each-ref --perl --format="%(refname)" >actual &&
-	git diff expected actual
+	test_cmp expected actual
 '
 
 test_expect_success 'Quoting style: python' '
 	git for-each-ref --python --format="%(refname)" >actual &&
-	git diff expected actual
+	test_cmp expected actual
 '
 
 cat >expected <<\EOF
@@ -196,7 +196,7 @@ EOF
 
 test_expect_success 'Quoting style: tcl' '
 	git for-each-ref --tcl --format="%(refname)" >actual &&
-	git diff expected actual
+	test_cmp expected actual
 '
 
 for i in "--perl --shell" "-s --python" "--python --tcl" "--tcl --perl"; do
diff --git a/t/t7003-filter-branch.sh b/t/t7003-filter-branch.sh
index 1639c7aa96..1e8a205e53 100755
--- a/t/t7003-filter-branch.sh
+++ b/t/t7003-filter-branch.sh
@@ -224,7 +224,7 @@ test_expect_success 'Tag name filtering retains tag message' '
 	git cat-file tag T > expect &&
 	git filter-branch -f --tag-name-filter cat &&
 	git cat-file tag T > actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 faux_gpg_tag='object XXXXXX
@@ -248,7 +248,7 @@ test_expect_success 'Tag name filtering strips gpg signature' '
 	echo "$faux_gpg_tag" | sed -e s/XXXXXX/$sha1/ | head -n 6 > expect &&
 	git filter-branch -f --tag-name-filter cat &&
 	git cat-file tag S > actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 test_done
diff --git a/t/t7004-tag.sh b/t/t7004-tag.sh
index 2dcee7ccc5..241c70dc66 100755
--- a/t/t7004-tag.sh
+++ b/t/t7004-tag.sh
@@ -116,9 +116,9 @@ mytag
 EOF
 test_expect_success \
 	'trying to delete tags without params should succeed and do nothing' '
-	git tag -l > actual && git diff expect actual &&
+	git tag -l > actual && test_cmp expect actual &&
 	git-tag -d &&
-	git tag -l > actual && git diff expect actual
+	git tag -l > actual && test_cmp expect actual
 '
 
 test_expect_success \
@@ -173,9 +173,9 @@ test_expect_success 'listing all tags should print them ordered' '
 	git tag v1.0 &&
 	git tag t210 &&
 	git tag -l > actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git tag > actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 cat >expect <<EOF
@@ -186,7 +186,7 @@ EOF
 test_expect_success \
 	'listing tags with substring as pattern must print those matching' '
 	git-tag -l "*a*" > actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 cat >expect <<EOF
@@ -196,7 +196,7 @@ EOF
 test_expect_success \
 	'listing tags with a suffix as pattern must print those matching' '
 	git-tag -l "*.1" > actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 cat >expect <<EOF
@@ -206,7 +206,7 @@ EOF
 test_expect_success \
 	'listing tags with a prefix as pattern must print those matching' '
 	git-tag -l "t21*" > actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 cat >expect <<EOF
@@ -215,7 +215,7 @@ EOF
 test_expect_success \
 	'listing tags using a name as pattern must print that one matching' '
 	git-tag -l a1 > actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 cat >expect <<EOF
@@ -224,7 +224,7 @@ EOF
 test_expect_success \
 	'listing tags using a name as pattern must print that one matching' '
 	git-tag -l v1.0 > actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 cat >expect <<EOF
@@ -234,14 +234,14 @@ EOF
 test_expect_success \
 	'listing tags with ? in the pattern should print those matching' '
 	git-tag -l "v1.?.?" > actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 >expect
 test_expect_success \
 	'listing tags using v.* should print nothing because none have v.' '
 	git-tag -l "v.*" > actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 cat >expect <<EOF
@@ -253,7 +253,7 @@ EOF
 test_expect_success \
 	'listing tags using v* should print only those having v' '
 	git-tag -l "v*" > actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 # creating and verifying lightweight tags:
@@ -302,7 +302,7 @@ test_expect_success \
 	'creating an annotated tag with -m message should succeed' '
 	git-tag -m "A message" annotated-tag &&
 	get_tag_msg annotated-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 cat >msgfile <<EOF
@@ -315,7 +315,7 @@ test_expect_success \
 	'creating an annotated tag with -F messagefile should succeed' '
 	git-tag -F msgfile file-annotated-tag &&
 	get_tag_msg file-annotated-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 cat >inputmsg <<EOF
@@ -327,7 +327,7 @@ cat inputmsg >>expect
 test_expect_success 'creating an annotated tag with -F - should succeed' '
 	git-tag -F - stdin-annotated-tag <inputmsg &&
 	get_tag_msg stdin-annotated-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 test_expect_success \
@@ -358,7 +358,7 @@ test_expect_success \
 	'creating a tag with an empty -m message should succeed' '
 	git-tag -m "" empty-annotated-tag &&
 	get_tag_msg empty-annotated-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 >emptyfile
@@ -367,7 +367,7 @@ test_expect_success \
 	'creating a tag with an empty -F messagefile should succeed' '
 	git-tag -F emptyfile emptyfile-annotated-tag &&
 	get_tag_msg emptyfile-annotated-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 printf '\n\n  \n\t\nLeading blank lines\n' >blanksfile
@@ -388,7 +388,7 @@ test_expect_success \
 	'extra blanks in the message for an annotated tag should be removed' '
 	git-tag -F blanksfile blanks-annotated-tag &&
 	get_tag_msg blanks-annotated-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 get_tag_header blank-annotated-tag $commit commit $time >expect
@@ -396,7 +396,7 @@ test_expect_success \
 	'creating a tag with blank -m message with spaces should succeed' '
 	git-tag -m "     " blank-annotated-tag &&
 	get_tag_msg blank-annotated-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 echo '     ' >blankfile
@@ -407,7 +407,7 @@ test_expect_success \
 	'creating a tag with blank -F messagefile with spaces should succeed' '
 	git-tag -F blankfile blankfile-annotated-tag &&
 	get_tag_msg blankfile-annotated-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 printf '      ' >blanknonlfile
@@ -416,7 +416,7 @@ test_expect_success \
 	'creating a tag with -F file of spaces and no newline should succeed' '
 	git-tag -F blanknonlfile blanknonlfile-annotated-tag &&
 	get_tag_msg blanknonlfile-annotated-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 # messages with commented lines:
@@ -451,7 +451,7 @@ test_expect_success \
 	'creating a tag using a -F messagefile with #comments should succeed' '
 	git-tag -F commentsfile comments-annotated-tag &&
 	get_tag_msg comments-annotated-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 get_tag_header comment-annotated-tag $commit commit $time >expect
@@ -459,7 +459,7 @@ test_expect_success \
 	'creating a tag with a #comment in the -m message should succeed' '
 	git-tag -m "#comment" comment-annotated-tag &&
 	get_tag_msg comment-annotated-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 echo '#comment' >commentfile
@@ -470,7 +470,7 @@ test_expect_success \
 	'creating a tag with #comments in the -F messagefile should succeed' '
 	git-tag -F commentfile commentfile-annotated-tag &&
 	get_tag_msg commentfile-annotated-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 printf '#comment' >commentnonlfile
@@ -479,7 +479,7 @@ test_expect_success \
 	'creating a tag with a file of #comment and no newline should succeed' '
 	git-tag -F commentnonlfile commentnonlfile-annotated-tag &&
 	get_tag_msg commentnonlfile-annotated-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 # listing messages for annotated non-signed tags:
@@ -490,23 +490,23 @@ test_expect_success \
 
 	echo "tag-one-line" >expect &&
 	git-tag -l | grep "^tag-one-line" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n0 -l | grep "^tag-one-line" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n0 -l tag-one-line >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 
 	echo "tag-one-line    A msg" >expect &&
 	git-tag -n1 -l | grep "^tag-one-line" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n -l | grep "^tag-one-line" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n1 -l tag-one-line >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n2 -l tag-one-line >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n999 -l tag-one-line >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 test_expect_success \
@@ -515,23 +515,23 @@ test_expect_success \
 
 	echo "tag-zero-lines" >expect &&
 	git-tag -l | grep "^tag-zero-lines" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n0 -l | grep "^tag-zero-lines" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n0 -l tag-zero-lines >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 
 	echo "tag-zero-lines  " >expect &&
 	git-tag -n1 -l | grep "^tag-zero-lines" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n -l | grep "^tag-zero-lines" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n1 -l tag-zero-lines >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n2 -l tag-zero-lines >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n999 -l tag-zero-lines >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 echo 'tag line one' >annotagmsg
@@ -543,39 +543,39 @@ test_expect_success \
 
 	echo "tag-lines" >expect &&
 	git-tag -l | grep "^tag-lines" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n0 -l | grep "^tag-lines" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n0 -l tag-lines >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 
 	echo "tag-lines       tag line one" >expect &&
 	git-tag -n1 -l | grep "^tag-lines" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n -l | grep "^tag-lines" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n1 -l tag-lines >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 
 	echo "    tag line two" >>expect &&
 	git-tag -n2 -l | grep "^ *tag.line" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n2 -l tag-lines >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 
 	echo "    tag line three" >>expect &&
 	git-tag -n3 -l | grep "^ *tag.line" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n3 -l tag-lines >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n4 -l | grep "^ *tag.line" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n4 -l tag-lines >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n99 -l | grep "^ *tag.line" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n99 -l tag-lines >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 # subsequent tests require gpg; check if it is available
@@ -635,7 +635,7 @@ echo '-----BEGIN PGP SIGNATURE-----' >>expect
 test_expect_success 'creating a signed tag with -m message should succeed' '
 	git-tag -s -m "A signed tag message" signed-tag &&
 	get_tag_msg signed-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 get_tag_header u-signed-tag $commit commit $time >expect
@@ -645,7 +645,7 @@ test_expect_success 'sign with a given key id' '
 
 	git tag -u committer@example.com -m "Another message" u-signed-tag &&
 	get_tag_msg u-signed-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 
 '
 
@@ -675,7 +675,7 @@ echo '-----BEGIN PGP SIGNATURE-----' >>expect
 test_expect_success '-u implies signed tag' '
 	GIT_EDITOR=./fakeeditor git-tag -u CDDE430D implied-sign &&
 	get_tag_msg implied-sign >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 cat >sigmsgfile <<EOF
@@ -689,7 +689,7 @@ test_expect_success \
 	'creating a signed tag with -F messagefile should succeed' '
 	git-tag -s -F sigmsgfile file-signed-tag &&
 	get_tag_msg file-signed-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 cat >siginputmsg <<EOF
@@ -702,7 +702,7 @@ echo '-----BEGIN PGP SIGNATURE-----' >>expect
 test_expect_success 'creating a signed tag with -F - should succeed' '
 	git-tag -s -F - stdin-signed-tag <siginputmsg &&
 	get_tag_msg stdin-signed-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 get_tag_header implied-annotate $commit commit $time >expect
@@ -711,7 +711,7 @@ echo '-----BEGIN PGP SIGNATURE-----' >>expect
 test_expect_success '-s implies annotated tag' '
 	GIT_EDITOR=./fakeeditor git-tag -s implied-annotate &&
 	get_tag_msg implied-annotate >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 test_expect_success \
@@ -752,7 +752,7 @@ test_expect_success \
 	'creating a signed tag with an empty -m message should succeed' '
 	git-tag -s -m "" empty-signed-tag &&
 	get_tag_msg empty-signed-tag >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -v empty-signed-tag
 '
 
@@ -763,7 +763,7 @@ test_expect_success \
 	'creating a signed tag with an empty -F messagefile should succeed' '
 	git-tag -s -F sigemptyfile emptyfile-signed-tag &&
 	get_tag_msg emptyfile-signed-tag >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -v emptyfile-signed-tag
 '
 
@@ -786,7 +786,7 @@ test_expect_success \
 	'extra blanks in the message for a signed tag should be removed' '
 	git-tag -s -F sigblanksfile blanks-signed-tag &&
 	get_tag_msg blanks-signed-tag >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -v blanks-signed-tag
 '
 
@@ -796,7 +796,7 @@ test_expect_success \
 	'creating a signed tag with a blank -m message should succeed' '
 	git-tag -s -m "     " blank-signed-tag &&
 	get_tag_msg blank-signed-tag >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -v blank-signed-tag
 '
 
@@ -809,7 +809,7 @@ test_expect_success \
 	'creating a signed tag with blank -F file with spaces should succeed' '
 	git-tag -s -F sigblankfile blankfile-signed-tag &&
 	get_tag_msg blankfile-signed-tag >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -v blankfile-signed-tag
 '
 
@@ -820,7 +820,7 @@ test_expect_success \
 	'creating a signed tag with spaces and no newline should succeed' '
 	git-tag -s -F sigblanknonlfile blanknonlfile-signed-tag &&
 	get_tag_msg blanknonlfile-signed-tag >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -v signed-tag
 '
 
@@ -857,7 +857,7 @@ test_expect_success \
 	'creating a signed tag with a -F file with #comments should succeed' '
 	git-tag -s -F sigcommentsfile comments-signed-tag &&
 	get_tag_msg comments-signed-tag >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -v comments-signed-tag
 '
 
@@ -867,7 +867,7 @@ test_expect_success \
 	'creating a signed tag with #commented -m message should succeed' '
 	git-tag -s -m "#comment" comment-signed-tag &&
 	get_tag_msg comment-signed-tag >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -v comment-signed-tag
 '
 
@@ -880,7 +880,7 @@ test_expect_success \
 	'creating a signed tag with #commented -F messagefile should succeed' '
 	git-tag -s -F sigcommentfile commentfile-signed-tag &&
 	get_tag_msg commentfile-signed-tag >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -v commentfile-signed-tag
 '
 
@@ -891,7 +891,7 @@ test_expect_success \
 	'creating a signed tag with a #comment and no newline should succeed' '
 	git-tag -s -F sigcommentnonlfile commentnonlfile-signed-tag &&
 	get_tag_msg commentnonlfile-signed-tag >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -v commentnonlfile-signed-tag
 '
 
@@ -903,23 +903,23 @@ test_expect_success \
 
 	echo "stag-one-line" >expect &&
 	git-tag -l | grep "^stag-one-line" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n0 -l | grep "^stag-one-line" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n0 -l stag-one-line >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 
 	echo "stag-one-line   A message line signed" >expect &&
 	git-tag -n1 -l | grep "^stag-one-line" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n -l | grep "^stag-one-line" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n1 -l stag-one-line >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n2 -l stag-one-line >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n999 -l stag-one-line >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 test_expect_success \
@@ -928,23 +928,23 @@ test_expect_success \
 
 	echo "stag-zero-lines" >expect &&
 	git-tag -l | grep "^stag-zero-lines" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n0 -l | grep "^stag-zero-lines" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n0 -l stag-zero-lines >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 
 	echo "stag-zero-lines " >expect &&
 	git-tag -n1 -l | grep "^stag-zero-lines" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n -l | grep "^stag-zero-lines" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n1 -l stag-zero-lines >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n2 -l stag-zero-lines >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n999 -l stag-zero-lines >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 echo 'stag line one' >sigtagmsg
@@ -956,39 +956,39 @@ test_expect_success \
 
 	echo "stag-lines" >expect &&
 	git-tag -l | grep "^stag-lines" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n0 -l | grep "^stag-lines" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n0 -l stag-lines >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 
 	echo "stag-lines      stag line one" >expect &&
 	git-tag -n1 -l | grep "^stag-lines" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n -l | grep "^stag-lines" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n1 -l stag-lines >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 
 	echo "    stag line two" >>expect &&
 	git-tag -n2 -l | grep "^ *stag.line" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n2 -l stag-lines >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 
 	echo "    stag line three" >>expect &&
 	git-tag -n3 -l | grep "^ *stag.line" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n3 -l stag-lines >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n4 -l | grep "^ *stag.line" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n4 -l stag-lines >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n99 -l | grep "^ *stag.line" >actual &&
-	git diff expect actual &&
+	test_cmp expect actual &&
 	git-tag -n99 -l stag-lines >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 # tags pointing to objects different from commits:
@@ -1004,7 +1004,7 @@ test_expect_success \
 	'creating a signed tag pointing to a tree should succeed' '
 	git-tag -s -m "A message for a tree" tree-signed-tag HEAD^{tree} &&
 	get_tag_msg tree-signed-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 get_tag_header blob-signed-tag $blob blob $time >expect
@@ -1014,7 +1014,7 @@ test_expect_success \
 	'creating a signed tag pointing to a blob should succeed' '
 	git-tag -s -m "A message for a blob" blob-signed-tag HEAD:foo &&
 	get_tag_msg blob-signed-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 get_tag_header tag-signed-tag $tag tag $time >expect
@@ -1024,7 +1024,7 @@ test_expect_success \
 	'creating a signed tag pointing to another tag should succeed' '
 	git-tag -s -m "A message for another tag" tag-signed-tag signed-tag &&
 	get_tag_msg tag-signed-tag >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 # try to sign with bad user.signingkey
@@ -1064,7 +1064,7 @@ test_expect_success \
 	git tag -a -m "An annotation to be reused" reuse &&
 	GIT_EDITOR=true git tag -f -a reuse &&
 	get_tag_msg reuse >actual &&
-	git diff expect actual
+	test_cmp expect actual
 '
 
 test_done
diff --git a/t/t7102-reset.sh b/t/t7102-reset.sh
index e5c9f30c73..39ba14148c 100755
--- a/t/t7102-reset.sh
+++ b/t/t7102-reset.sh
@@ -34,13 +34,13 @@ test_expect_success 'creating initial files and commits' '
 
 check_changes () {
 	test "$(git rev-parse HEAD)" = "$1" &&
-	git diff | git diff .diff_expect - &&
-	git diff --cached | git diff .cached_expect - &&
+	git diff | test_cmp .diff_expect - &&
+	git diff --cached | test_cmp .cached_expect - &&
 	for FILE in *
 	do
 		echo $FILE':'
 		cat $FILE || return
-	done | git diff .cat_expect -
+	done | test_cmp .cat_expect -
 }
 
 >.diff_expect
@@ -390,9 +390,9 @@ test_expect_success 'test --mixed <paths>' '
 	git add file1 file3 file4 &&
 	! git reset HEAD -- file1 file2 file3 &&
 	git diff > output &&
-	git diff output expect &&
+	test_cmp output expect &&
 	git diff --cached > output &&
-	git diff output cached_expect
+	test_cmp output cached_expect
 '
 
 test_expect_success 'test resetting the index at give paths' '
@@ -425,7 +425,7 @@ EOF
 test_expect_success '--mixed refreshes the index' '
 	echo 123 >> file2 &&
 	git reset --mixed HEAD > output &&
-	git diff --exit-code expect output
+	test_cmp expect output
 '
 
 test_done
diff --git a/t/t7502-status.sh b/t/t7502-status.sh
index e4bfcaece0..80a438d4d9 100755
--- a/t/t7502-status.sh
+++ b/t/t7502-status.sh
@@ -63,7 +63,7 @@ EOF
 test_expect_success 'status (2)' '
 
 	git status > output &&
-	git diff expect output
+	test_cmp expect output
 
 '
 
@@ -93,7 +93,7 @@ EOF
 test_expect_success 'status with relative paths' '
 
 	(cd dir1 && git status) > output &&
-	git diff expect output
+	test_cmp expect output
 
 '
 
@@ -124,7 +124,7 @@ test_expect_success 'status without relative paths' '
 
 	git config status.relativePaths false
 	(cd dir1 && git status) > output &&
-	git diff expect output
+	test_cmp expect output
 
 '
 
diff --git a/t/t9100-git-svn-basic.sh b/t/t9100-git-svn-basic.sh
index bdf29c1734..242cdf092a 100755
--- a/t/t9100-git-svn-basic.sh
+++ b/t/t9100-git-svn-basic.sh
@@ -169,7 +169,7 @@ test_expect_success "$name" '
 	svn up "$SVN_TREE" &&
 	test -f "$SVN_TREE"/exec-2.sh &&
 	test ! -L "$SVN_TREE"/exec-2.sh &&
-	git diff help "$SVN_TREE"/exec-2.sh'
+	test_cmp help "$SVN_TREE"/exec-2.sh'
 
 if test "$have_utf8" = t
 then
@@ -193,7 +193,7 @@ test_expect_success "$name" \
     'git-svn init "$svnrepo" && git-svn fetch &&
      git rev-list --pretty=raw remotes/git-svn | grep ^tree | uniq > a &&
      git rev-list --pretty=raw remotes/alt | grep ^tree | uniq > b &&
-     git diff a b'
+     test_cmp a b'
 
 name='check imported tree checksums expected tree checksums'
 rm -f expected
@@ -211,7 +211,7 @@ tree d667270a1f7b109f5eb3aaea21ede14b56bfdd6e
 tree 8f51f74cf0163afc9ad68a4b1537288c4558b5a4
 EOF
 
-test_expect_success "$name" "git diff a expected"
+test_expect_success "$name" "test_cmp a expected"
 
 test_expect_success 'exit if remote refs are ambigious' "
         git config --add svn-remote.svn.fetch \
diff --git a/t/t9300-fast-import.sh b/t/t9300-fast-import.sh
index c4f4465dc6..5edf56f198 100755
--- a/t/t9300-fast-import.sh
+++ b/t/t9300-fast-import.sh
@@ -74,7 +74,7 @@ EOF
 test_expect_success \
 	'A: verify commit' \
 	'git cat-file commit master | sed 1d >actual &&
-	git diff expect actual'
+	test_cmp expect actual'
 
 cat >expect <<EOF
 100644 blob file2
@@ -84,22 +84,22 @@ EOF
 test_expect_success \
 	'A: verify tree' \
 	'git cat-file -p master^{tree} | sed "s/ [0-9a-f]*	/ /" >actual &&
-	 git diff expect actual'
+	 test_cmp expect actual'
 
 echo "$file2_data" >expect
 test_expect_success \
 	'A: verify file2' \
-	'git cat-file blob master:file2 >actual && git diff expect actual'
+	'git cat-file blob master:file2 >actual && test_cmp expect actual'
 
 echo "$file3_data" >expect
 test_expect_success \
 	'A: verify file3' \
-	'git cat-file blob master:file3 >actual && git diff expect actual'
+	'git cat-file blob master:file3 >actual && test_cmp expect actual'
 
 printf "$file4_data" >expect
 test_expect_success \
 	'A: verify file4' \
-	'git cat-file blob master:file4 >actual && git diff expect actual'
+	'git cat-file blob master:file4 >actual && test_cmp expect actual'
 
 cat >expect <<EOF
 :2 `git rev-parse --verify master:file2`
@@ -109,7 +109,7 @@ cat >expect <<EOF
 EOF
 test_expect_success \
 	'A: verify marks output' \
-	'git diff expect marks.out'
+	'test_cmp expect marks.out'
 
 test_expect_success \
 	'A: verify marks import' \
@@ -117,7 +117,7 @@ test_expect_success \
 		--import-marks=marks.out \
 		--export-marks=marks.new \
 		</dev/null &&
-	git diff -u expect marks.new'
+	test_cmp expect marks.new'
 
 test_tick
 cat >input <<INPUT_END
@@ -259,7 +259,7 @@ EOF
 test_expect_success \
 	'C: verify commit' \
 	'git cat-file commit branch | sed 1d >actual &&
-	 git diff expect actual'
+	 test_cmp expect actual'
 
 cat >expect <<EOF
 :000000 100755 0000000000000000000000000000000000000000 f1fb5da718392694d0076d677d6d0e364c79b0bc A	file2/newf
@@ -316,13 +316,13 @@ echo "$file5_data" >expect
 test_expect_success \
 	'D: verify file5' \
 	'git cat-file blob branch:newdir/interesting >actual &&
-	 git diff expect actual'
+	 test_cmp expect actual'
 
 echo "$file6_data" >expect
 test_expect_success \
 	'D: verify file6' \
 	'git cat-file blob branch:newdir/exec.sh >actual &&
-	 git diff expect actual'
+	 test_cmp expect actual'
 
 ###
 ### series E
@@ -358,7 +358,7 @@ EOF
 test_expect_success \
 	'E: verify commit' \
 	'git cat-file commit branch | sed 1,2d >actual &&
-	git diff expect actual'
+	test_cmp expect actual'
 
 ###
 ### series F
@@ -411,7 +411,7 @@ EOF
 test_expect_success \
 	'F: verify other commit' \
 	'git cat-file commit other >actual &&
-	git diff expect actual'
+	test_cmp expect actual'
 
 ###
 ### series G
@@ -489,7 +489,7 @@ echo "$file5_data" >expect
 test_expect_success \
 	'H: verify file' \
 	'git cat-file blob H:h/e/l/lo >actual &&
-	 git diff expect actual'
+	 test_cmp expect actual'
 
 ###
 ### series I
@@ -515,7 +515,7 @@ EOF
 test_expect_success \
 	'I: verify edge list' \
 	'sed -e s/pack-.*pack/pack-.pack/ edges.list >actual &&
-	 git diff expect actual'
+	 test_cmp expect actual'
 
 ###
 ### series J
@@ -625,7 +625,7 @@ test_expect_success \
     'L: verify internal tree sorting' \
 	'git-fast-import <input &&
 	 git diff-tree --abbrev --raw L^ L >output &&
-	 git diff expect output'
+	 test_cmp expect output'
 
 ###
 ### series M
@@ -885,7 +885,7 @@ test_expect_success \
 	 test 8 = `find .git/objects/pack -type f | wc -l` &&
 	 test `git rev-parse refs/tags/O3-2nd` = `git rev-parse O3^` &&
 	 git log --reverse --pretty=oneline O3 | sed s/^.*z// >actual &&
-	 git diff expect actual'
+	 test_cmp expect actual'
 
 cat >input <<INPUT_END
 commit refs/heads/O4
@@ -916,6 +916,6 @@ test_expect_success \
 	'O: progress outputs as requested by input' \
 	'git-fast-import <input >actual &&
 	 grep "progress " <input >expect &&
-	 git diff expect actual'
+	 test_cmp expect actual'
 
 test_done
diff --git a/t/t9600-cvsimport.sh b/t/t9600-cvsimport.sh
index 0b115a17ab..655f88270b 100755
--- a/t/t9600-cvsimport.sh
+++ b/t/t9600-cvsimport.sh
@@ -69,7 +69,7 @@ EOF
 test_expect_success 'import a trivial module' '
 
 	git cvsimport -a -z 0 -C module-git module &&
-	git diff module-cvs/o_fortuna module-git/o_fortuna
+	test_cmp module-cvs/o_fortuna module-git/o_fortuna
 
 '
 
@@ -110,7 +110,7 @@ test_expect_success 'update git module' '
 	git cvsimport -a -z 0 module &&
 	git merge origin &&
 	cd .. &&
-	git diff module-cvs/o_fortuna module-git/o_fortuna
+	test_cmp module-cvs/o_fortuna module-git/o_fortuna
 
 '
 
@@ -131,7 +131,7 @@ test_expect_success 'cvsimport.module config works' '
 		git cvsimport -a -z0 &&
 		git merge origin &&
 	cd .. &&
-	git diff module-cvs/tick module-git/tick
+	test_cmp module-cvs/tick module-git/tick
 
 '
 
@@ -142,7 +142,7 @@ test_expect_success 'import from a CVS working tree' '
 		git cvsimport -a -z0 &&
 		echo 1 >expect &&
 		git log -1 --pretty=format:%s%n >actual &&
-		git diff actual expect &&
+		test_cmp actual expect &&
 	cd ..
 
 '