More tests and fix submodule index refresh

There was a little bug where the submodule cache thought that the
index date was out of date even when it wasn't that was resulting
in some extra scans of index data even when not needed.

Mostly this commit adds a bunch of new tests including adding and
removing submodules in the index and in the HEAD and seeing if we
can automatically pick them up when refreshing.

4 files changed, 132 insertions, 14 deletions

diff --git a/src/index.c b/src/index.c
index 6cc8ea1a3..24e447928 100644
--- a/src/index.c
+++ b/src/index.c
@@ -524,7 +524,9 @@ int git_index__changed_relative_to(
 	if (git_index_read(index, false) < 0)
 		giterr_clear();
 
-	return (memcmp(&index->stamp, fs, sizeof(index->stamp)) == 0);
+	return (index->stamp.mtime != fs->mtime ||
+			index->stamp.size != fs->size ||
+			index->stamp.ino != fs->ino);
 }
 
 int git_index_write(git_index *index)
diff --git a/tests/submodule/lookup.c b/tests/submodule/lookup.c
index 86ba25c3a..34de5923e 100644
--- a/tests/submodule/lookup.c
+++ b/tests/submodule/lookup.c
@@ -130,18 +130,63 @@ void test_submodule_lookup__lookup_even_with_missing_index(void)
 	test_submodule_lookup__simple_lookup(); /* baseline should still pass */
 }
 
+static void baseline_tests(void)
+{
+	/* small baseline that should work even if we change the index or make
+	 * commits from the index
+	 */
+	assert_submodule_exists(g_repo, "sm_unchanged");
+	assert_submodule_exists(g_repo, "sm_gitmodules_only");
+	refute_submodule_exists(g_repo, "not-submodule", GIT_EEXISTS);
+}
+
+static void add_submodule_with_commit(const char *name)
+{
+	git_submodule *sm;
+	git_repository *smrepo;
+	git_index *idx;
+	git_buf p = GIT_BUF_INIT;
+
+	cl_git_pass(git_submodule_add_setup(&sm, g_repo,
+		"https://github.com/libgit2/libgit2.git", name, 1));
+
+	assert_submodule_exists(g_repo, name);
+
+	cl_git_pass(git_submodule_open(&smrepo, sm));
+	cl_git_pass(git_repository_index(&idx, smrepo));
+
+	cl_git_pass(git_buf_joinpath(&p, git_repository_workdir(smrepo), "file"));
+	cl_git_mkfile(p.ptr, "new file");
+	git_buf_free(&p);
+
+	cl_git_pass(git_index_add_bypath(idx, "file"));
+	cl_git_pass(git_index_write(idx));
+	git_index_free(idx);
+
+	cl_repo_commit_from_index(NULL, smrepo, NULL, 0, "initial commit");
+	git_repository_free(smrepo);
+
+	cl_git_pass(git_submodule_add_finalize(sm));
+
+	git_submodule_free(sm);
+}
+
 void test_submodule_lookup__just_added(void)
 {
 	git_submodule *sm;
 	git_buf snap1 = GIT_BUF_INIT, snap2 = GIT_BUF_INIT;
+	git_reference *original_head = NULL;
 
 	refute_submodule_exists(g_repo, "sm_just_added", GIT_ENOTFOUND);
 	refute_submodule_exists(g_repo, "sm_just_added_2", GIT_ENOTFOUND);
+	refute_submodule_exists(g_repo, "sm_just_added_idx", GIT_ENOTFOUND);
+	refute_submodule_exists(g_repo, "sm_just_added_head", GIT_ENOTFOUND);
 	refute_submodule_exists(g_repo, "mismatch_name", GIT_ENOTFOUND);
 	refute_submodule_exists(g_repo, "mismatch_path", GIT_ENOTFOUND);
-	test_submodule_lookup__simple_lookup(); /* baseline */
+	baseline_tests();
 
 	cl_git_pass(git_futils_readbuffer(&snap1, "submod2/.gitmodules"));
+	cl_git_pass(git_repository_head(&original_head, g_repo));
 
 	cl_git_pass(git_submodule_add_setup(&sm, g_repo,
 		"https://github.com/libgit2/libgit2.git", "sm_just_added", 1));
@@ -151,8 +196,16 @@ void test_submodule_lookup__just_added(void)
 	cl_git_pass(git_submodule_add_setup(&sm, g_repo,
 		"https://github.com/libgit2/libgit2.git", "sm_just_added_2", 1));
 	assert_submodule_exists(g_repo, "sm_just_added_2");
+	cl_git_fail(git_submodule_add_finalize(sm)); /* fails if no HEAD */
 	git_submodule_free(sm);
 
+	add_submodule_with_commit("sm_just_added_head");
+	cl_repo_commit_from_index(NULL, g_repo, NULL, 0, "commit new sm to head");
+	assert_submodule_exists(g_repo, "sm_just_added_head");
+
+	add_submodule_with_commit("sm_just_added_idx");
+	assert_submodule_exists(g_repo, "sm_just_added_idx");
+
 	cl_git_pass(git_futils_readbuffer(&snap2, "submod2/.gitmodules"));
 
 	cl_git_append2file(
@@ -165,7 +218,9 @@ void test_submodule_lookup__just_added(void)
 	assert_submodule_exists(g_repo, "mismatch_path");
 	assert_submodule_exists(g_repo, "sm_just_added");
 	assert_submodule_exists(g_repo, "sm_just_added_2");
-	test_submodule_lookup__simple_lookup();
+	assert_submodule_exists(g_repo, "sm_just_added_idx");
+	assert_submodule_exists(g_repo, "sm_just_added_head");
+	baseline_tests();
 
 	cl_git_rewritefile("submod2/.gitmodules", snap2.ptr);
 	git_buf_free(&snap2);
@@ -174,7 +229,9 @@ void test_submodule_lookup__just_added(void)
 	refute_submodule_exists(g_repo, "mismatch_path", GIT_ENOTFOUND);
 	assert_submodule_exists(g_repo, "sm_just_added");
 	assert_submodule_exists(g_repo, "sm_just_added_2");
-	test_submodule_lookup__simple_lookup();
+	assert_submodule_exists(g_repo, "sm_just_added_idx");
+	assert_submodule_exists(g_repo, "sm_just_added_head");
+	baseline_tests();
 
 	cl_git_rewritefile("submod2/.gitmodules", snap1.ptr);
 	git_buf_free(&snap1);
@@ -184,5 +241,31 @@ void test_submodule_lookup__just_added(void)
 	/* note error code change, because add_setup made a repo in the workdir */
 	refute_submodule_exists(g_repo, "sm_just_added", GIT_EEXISTS);
 	refute_submodule_exists(g_repo, "sm_just_added_2", GIT_EEXISTS);
-	test_submodule_lookup__simple_lookup();
+	/* these still exist in index and head respectively */
+	assert_submodule_exists(g_repo, "sm_just_added_idx");
+	assert_submodule_exists(g_repo, "sm_just_added_head");
+	baseline_tests();
+
+	{
+		git_index *idx;
+		cl_git_pass(git_repository_index(&idx, g_repo));
+		cl_git_pass(git_index_remove_bypath(idx, "sm_just_added_idx"));
+		cl_git_pass(git_index_remove_bypath(idx, "sm_just_added_head"));
+		cl_git_pass(git_index_write(idx));
+		git_index_free(idx);
+	}
+
+	refute_submodule_exists(g_repo, "sm_just_added_idx", GIT_EEXISTS);
+	assert_submodule_exists(g_repo, "sm_just_added_head");
+
+	{
+		git_signature *sig;
+		cl_git_pass(git_signature_now(&sig, "resetter", "resetter@email.com"));
+		cl_git_pass(git_reference_create(NULL, g_repo, "refs/heads/master", git_reference_target(original_head), 1, sig, "move head back"));
+		git_signature_free(sig);
+		git_reference_free(original_head);
+	}
+
+	refute_submodule_exists(g_repo, "sm_just_added_head", GIT_EEXISTS);
 }
+
diff --git a/tests/submodule/submodule_helpers.c b/tests/submodule/submodule_helpers.c
index 546f0913a..50aa97568 100644
--- a/tests/submodule/submodule_helpers.c
+++ b/tests/submodule/submodule_helpers.c
@@ -126,20 +126,26 @@ git_repository *setup_fixture_submod2(void)
 	return repo;
 }
 
-void assert_submodule_exists(git_repository *repo, const char *name)
+void assert__submodule_exists(
+	git_repository *repo, const char *name,
+	const char *msg, const char *file, int line)
 {
 	git_submodule *sm;
-	cl_git_pass(git_submodule_lookup(&sm, repo, name));
-	cl_assert(sm);
+	int error = git_submodule_lookup(&sm, repo, name);
+	if (error)
+		cl_git_report_failure(error, file, line, msg);
+	cl_assert_at_line(sm != NULL, file, line);
 	git_submodule_free(sm);
 }
 
-void refute_submodule_exists(
-	git_repository *repo, const char *name, int expected_error)
+void refute__submodule_exists(
+	git_repository *repo, const char *name, int expected_error,
+	const char *msg, const char *file, int line)
 {
 	git_submodule *sm;
-	cl_assert_equal_i(
-		expected_error, git_submodule_lookup(&sm, repo, name));
+	clar__assert_equal(
+		file, line, msg, 1, "%i",
+		expected_error, (int)(git_submodule_lookup(&sm, repo, name)));
 }
 
 unsigned int get_submodule_status(git_repository *repo, const char *name)
@@ -154,3 +160,19 @@ unsigned int get_submodule_status(git_repository *repo, const char *name)
 
 	return status;
 }
+
+static int print_submodules(git_submodule *sm, const char *name, void *p)
+{
+	unsigned int loc = 0;
+	GIT_UNUSED(p);
+	git_submodule_location(&loc, sm);
+	fprintf(stderr, "# submodule %s (at %s) flags %x\n",
+		name, git_submodule_path(sm), loc);
+	return 0;
+}
+
+void dump_submodules(git_repository *repo)
+{
+	git_submodule_foreach(repo, print_submodules, NULL);
+}
+
diff --git a/tests/submodule/submodule_helpers.h b/tests/submodule/submodule_helpers.h
index ec5510e3c..4b2620bfa 100644
--- a/tests/submodule/submodule_helpers.h
+++ b/tests/submodule/submodule_helpers.h
@@ -6,5 +6,16 @@ extern git_repository *setup_fixture_submod2(void);
 
 extern unsigned int get_submodule_status(git_repository *, const char *);
 
-extern void assert_submodule_exists(git_repository *, const char *);
-extern void refute_submodule_exists(git_repository *, const char *, int err);
+extern void assert__submodule_exists(
+	git_repository *, const char *, const char *, const char *, int);
+
+#define assert_submodule_exists(repo,name)								\
+	assert__submodule_exists(repo, name, "git_submodule_lookup(" #name ") failed", __FILE__, __LINE__)
+
+extern void refute__submodule_exists(
+	git_repository *, const char *, int err, const char *, const char *, int);
+
+#define refute_submodule_exists(repo,name,code) \
+	refute__submodule_exists(repo, name, code, "expected git_submodule_lookup(" #name ") to fail with error " #code, __FILE__, __LINE__)
+
+extern void dump_submodules(git_repository *repo);