introduce `git_diff_from_buffer` to parse diffs

Parse diff files into a `git_diff` structure.

1 files changed, 60 insertions, 0 deletions

diff --git a/tests/diff/parse.c b/tests/diff/parse.c
new file mode 100644
index 000000000..8eb98423b
--- /dev/null
+++ b/tests/diff/parse.c
@@ -0,0 +1,60 @@
+#include "clar_libgit2.h"
+#include "patch.h"
+#include "patch_parse.h"
+
+#include "../patch/patch_common.h"
+
+void test_diff_parse__nonpatches_fail_with_notfound(void)
+{
+	git_diff *diff;
+	const char *not = PATCH_NOT_A_PATCH;
+	const char *not_with_leading = "Leading text.\n" PATCH_NOT_A_PATCH;
+	const char *not_with_trailing = PATCH_NOT_A_PATCH "Trailing text.\n";
+	const char *not_with_both = "Lead.\n" PATCH_NOT_A_PATCH "Trail.\n";
+
+	cl_git_fail_with(GIT_ENOTFOUND,
+		git_diff_from_buffer(&diff,
+		not,
+		strlen(not)));
+	cl_git_fail_with(GIT_ENOTFOUND,
+		git_diff_from_buffer(&diff,
+		not_with_leading,
+		strlen(not_with_leading)));
+	cl_git_fail_with(GIT_ENOTFOUND,
+		git_diff_from_buffer(&diff,
+		not_with_trailing,
+		strlen(not_with_trailing)));
+	cl_git_fail_with(GIT_ENOTFOUND,
+		git_diff_from_buffer(&diff,
+		not_with_both,
+		strlen(not_with_both)));
+}
+
+static void test_parse_invalid_diff(const char *invalid_diff)
+{
+	git_diff *diff;
+	git_buf buf = GIT_BUF_INIT;
+
+	/* throw some random (legitimate) diffs in with the given invalid
+	 * one.
+	 */
+	git_buf_puts(&buf, PATCH_ORIGINAL_TO_CHANGE_FIRSTLINE);
+	git_buf_puts(&buf, PATCH_BINARY_DELTA);
+	git_buf_puts(&buf, invalid_diff);
+	git_buf_puts(&buf, PATCH_ORIGINAL_TO_CHANGE_MIDDLE);
+	git_buf_puts(&buf, PATCH_BINARY_LITERAL);
+
+	cl_git_fail_with(GIT_ERROR,
+		git_diff_from_buffer(&diff, buf.ptr, buf.size));
+
+	git_buf_free(&buf);
+}
+
+void test_diff_parse__invalid_patches_fails(void)
+{
+	test_parse_invalid_diff(PATCH_CORRUPT_MISSING_NEW_FILE);
+	test_parse_invalid_diff(PATCH_CORRUPT_MISSING_OLD_FILE);
+	test_parse_invalid_diff(PATCH_CORRUPT_NO_CHANGES);
+	test_parse_invalid_diff(PATCH_CORRUPT_MISSING_HUNK_HEADER);
+}
+