thodg/libgit2

diff --git a/tests-clar/clar_libgit2.c b/tests-clar/clar_libgit2.c
index 522f736..4cf6824 100644
--- a/tests-clar/clar_libgit2.c
+++ b/tests-clar/clar_libgit2.c
@@ -337,6 +337,65 @@ int cl_git_remove_placeholders(const char *directory_path, const char *filename)
 	return error;
 }
 
+#define CL_COMMIT_NAME "Libgit2 Tester"
+#define CL_COMMIT_EMAIL "libgit2-test@github.com"
+#define CL_COMMIT_MSG "Test commit of tree "
+
+void cl_repo_commit_from_index(
+	git_oid *out,
+	git_repository *repo,
+	git_signature *sig,
+	git_time_t time,
+	const char *msg)
+{
+	git_index *index;
+	git_oid commit_id, tree_id;
+	git_object *parent = NULL;
+	git_reference *ref = NULL;
+	git_tree *tree = NULL;
+	char buf[128];
+	int free_sig = (sig == NULL);
+
+	/* it is fine if looking up HEAD fails - we make this the first commit */
+	git_revparse_ext(&parent, &ref, repo, "HEAD");
+
+	/* write the index content as a tree */
+	cl_git_pass(git_repository_index(&index, repo));
+	cl_git_pass(git_index_write_tree(&tree_id, index));
+	cl_git_pass(git_index_write(index));
+	git_index_free(index);
+
+	cl_git_pass(git_tree_lookup(&tree, repo, &tree_id));
+
+	if (sig)
+		cl_assert(sig->name && sig->email);
+	else if (!time)
+		cl_git_pass(git_signature_now(&sig, CL_COMMIT_NAME, CL_COMMIT_EMAIL));
+	else
+		cl_git_pass(git_signature_new(
+			&sig, CL_COMMIT_NAME, CL_COMMIT_EMAIL, time, 0));
+
+	if (!msg) {
+		strcpy(buf, CL_COMMIT_MSG);
+		git_oid_tostr(buf + strlen(CL_COMMIT_MSG),
+			sizeof(buf) - strlen(CL_COMMIT_MSG), &tree_id);
+		msg = buf;
+	}
+
+	cl_git_pass(git_commit_create_v(
+		&commit_id, repo, ref ? git_reference_name(ref) : "HEAD",
+		sig, sig, NULL, msg, tree, parent ? 1 : 0, parent));
+
+	if (out)
+		git_oid_cpy(out, &commit_id);
+
+	git_object_free(parent);
+	git_reference_free(ref);
+	if (free_sig)
+		git_signature_free(sig);
+	git_tree_free(tree);
+}
+
 void cl_repo_set_bool(git_repository *repo, const char *cfg, int value)
 {
 	git_config *config;
diff --git a/tests-clar/clar_libgit2.h b/tests-clar/clar_libgit2.h
index 76299e4..f2d9c4d 100644
--- a/tests-clar/clar_libgit2.h
+++ b/tests-clar/clar_libgit2.h
@@ -98,6 +98,14 @@ const char* cl_git_path_url(const char *path);
 /* Test repository cleaner */
 int cl_git_remove_placeholders(const char *directory_path, const char *filename);
 
+/* commit creation helpers */
+void cl_repo_commit_from_index(
+	git_oid *out,
+	git_repository *repo,
+	git_signature *sig,
+	git_time_t time,
+	const char *msg);
+
 /* config setting helpers */
 void cl_repo_set_bool(git_repository *repo, const char *cfg, int value);
 int cl_repo_get_bool(git_repository *repo, const char *cfg);
diff --git a/tests-clar/diff/submodules.c b/tests-clar/diff/submodules.c
index 167dedf..036ff09 100644
--- a/tests-clar/diff/submodules.c
+++ b/tests-clar/diff/submodules.c
@@ -228,11 +228,11 @@ void test_diff_submodules__invalid_cache(void)
 		"<END>"
 	};
 	static const char *expected_moved[] = {
-		"diff --git a/sm_changed_head b/sm_changed_head\nindex 3d9386c..0910a13 160000\n--- a/sm_changed_head\n+++ b/sm_changed_head\n@@ -1 +1 @@\n-Subproject commit 3d9386c507f6b093471a3e324085657a3c2b4247\n+Subproject commit 0910a13dfa2210496f6c590d75bc360dd11b2a1b\n",
+		"diff --git a/sm_changed_head b/sm_changed_head\nindex 3d9386c..7002348 160000\n--- a/sm_changed_head\n+++ b/sm_changed_head\n@@ -1 +1 @@\n-Subproject commit 3d9386c507f6b093471a3e324085657a3c2b4247\n+Subproject commit 700234833f6ccc20d744b238612646be071acaae\n",
 		"<END>"
 	};
 	static const char *expected_moved_dirty[] = {
-		"diff --git a/sm_changed_head b/sm_changed_head\nindex 3d9386c..0910a13 160000\n--- a/sm_changed_head\n+++ b/sm_changed_head\n@@ -1 +1 @@\n-Subproject commit 3d9386c507f6b093471a3e324085657a3c2b4247\n+Subproject commit 0910a13dfa2210496f6c590d75bc360dd11b2a1b-dirty\n",
+		"diff --git a/sm_changed_head b/sm_changed_head\nindex 3d9386c..7002348 160000\n--- a/sm_changed_head\n+++ b/sm_changed_head\n@@ -1 +1 @@\n-Subproject commit 3d9386c507f6b093471a3e324085657a3c2b4247\n+Subproject commit 700234833f6ccc20d744b238612646be071acaae-dirty\n",
 		"<END>"
 	};
 
@@ -309,26 +309,7 @@ void test_diff_submodules__invalid_cache(void)
 	git_diff_list_free(diff);
 
 	/* commit changed index of submodule */
-	{
-		git_object *parent;
-		git_oid tree_id, commit_id;
-		git_tree *tree;
-		git_signature *sig;
-		git_reference *ref;
-
-		cl_git_pass(git_revparse_ext(&parent, &ref, smrepo, "HEAD"));
-		cl_git_pass(git_index_write_tree(&tree_id, smindex));
-		cl_git_pass(git_index_write(smindex));
-		cl_git_pass(git_tree_lookup(&tree, smrepo, &tree_id));
-		cl_git_pass(git_signature_new(&sig, "Sm Test", "sm@tester.test", 1372350000, 480));
-		cl_git_pass(git_commit_create_v(
-			&commit_id, smrepo, git_reference_name(ref), sig, sig,
-			NULL, "Move it", tree, 1, parent));
-		git_object_free(parent);
-		git_tree_free(tree);
-		git_reference_free(ref);
-		git_signature_free(sig);
-	}
+	cl_repo_commit_from_index(NULL, smrepo, NULL, 1372350000, "Move it");
 
 	git_submodule_set_ignore(sm, GIT_SUBMODULE_IGNORE_DIRTY);
 
diff --git a/tests-clar/index/addall.c b/tests-clar/index/addall.c
index 00388ee..f46a1e1 100644
--- a/tests-clar/index/addall.c
+++ b/tests-clar/index/addall.c
@@ -120,37 +120,6 @@ static void check_stat_data(git_index *index, const char *path, bool match)
 	}
 }
 
-static void commit_index_to_head(
-	git_repository *repo,
-	const char *commit_message)
-{
-	git_index *index;
-	git_oid tree_id, commit_id;
-	git_tree *tree;
-	git_signature *sig;
-	git_commit *parent = NULL;
-
-	git_revparse_single((git_object **)&parent, repo, "HEAD");
-	/* it is okay if looking up the HEAD fails */
-
-	cl_git_pass(git_repository_index(&index, repo));
-	cl_git_pass(git_index_write_tree(&tree_id, index));
-	cl_git_pass(git_index_write(index)); /* not needed, but might as well */
-	git_index_free(index);
-
-	cl_git_pass(git_tree_lookup(&tree, repo, &tree_id));
-
-	cl_git_pass(git_signature_now(&sig, "Testy McTester", "tt@tester.test"));
-
-	cl_git_pass(git_commit_create_v(
-		&commit_id, repo, "HEAD", sig, sig,
-		NULL, commit_message, tree, parent ? 1 : 0, parent));
-
-	git_commit_free(parent);
-	git_tree_free(tree);
-	git_signature_free(sig);
-}
-
 void test_index_addall__repo_lifecycle(void)
 {
 	int error;
@@ -197,7 +166,7 @@ void test_index_addall__repo_lifecycle(void)
 	check_stat_data(index, "addall/file.zzz", true);
 	check_status(g_repo, 2, 0, 0, 3, 0, 0, 1);
 
-	commit_index_to_head(g_repo, "first commit");
+	cl_repo_commit_from_index(NULL, g_repo, NULL, 0, "first commit");
 	check_status(g_repo, 0, 0, 0, 3, 0, 0, 1);
 
 	/* attempt to add an ignored file - does nothing */
@@ -244,7 +213,7 @@ void test_index_addall__repo_lifecycle(void)
 	cl_git_pass(git_index_add_bypath(index, "file.zzz"));
 	check_status(g_repo, 1, 0, 1, 3, 0, 0, 0);
 
-	commit_index_to_head(g_repo, "second commit");
+	cl_repo_commit_from_index(NULL, g_repo, NULL, 0, "second commit");
 	check_status(g_repo, 0, 0, 0, 3, 0, 0, 0);
 
 	cl_must_pass(p_unlink("addall/file.zzz"));
diff --git a/tests-clar/repo/init.c b/tests-clar/repo/init.c
index e3fc112..caa211e 100644
--- a/tests-clar/repo/init.c
+++ b/tests-clar/repo/init.c
@@ -565,6 +565,11 @@ void test_repo_init__init_with_initial_commit(void)
 	cl_git_pass(git_index_add_bypath(index, "file.txt"));
 	cl_git_pass(git_index_write(index));
 
+	/* Intentionally not using cl_repo_commit_from_index here so this code
+	 * can be used as an example of how an initial commit is typically
+	 * made to a repository...
+	 */
+
 	/* Make sure we're ready to use git_signature_default :-) */
 	{
 		git_config *cfg, *local;
diff --git a/tests-clar/stash/drop.c b/tests-clar/stash/drop.c
index 60b3c72..59413f0 100644
--- a/tests-clar/stash/drop.c
+++ b/tests-clar/stash/drop.c
@@ -36,25 +36,27 @@ static void push_three_states(void)
 	cl_git_mkfile("stash/zero.txt", "content\n");
 	cl_git_pass(git_repository_index(&index, repo));
 	cl_git_pass(git_index_add_bypath(index, "zero.txt"));
-	commit_staged_files(&oid, index, signature);
+	cl_repo_commit_from_index(NULL, repo, signature, 0, "Initial commit");
 	cl_assert(git_path_exists("stash/zero.txt"));
+	git_index_free(index);
 
 	cl_git_mkfile("stash/one.txt", "content\n");
-	cl_git_pass(git_stash_save(&oid, repo, signature, "First", GIT_STASH_INCLUDE_UNTRACKED));
+	cl_git_pass(git_stash_save(
+		&oid, repo, signature, "First", GIT_STASH_INCLUDE_UNTRACKED));
 	cl_assert(!git_path_exists("stash/one.txt"));
 	cl_assert(git_path_exists("stash/zero.txt"));
 
 	cl_git_mkfile("stash/two.txt", "content\n");
-	cl_git_pass(git_stash_save(&oid, repo, signature, "Second", GIT_STASH_INCLUDE_UNTRACKED));
+	cl_git_pass(git_stash_save(
+		&oid, repo, signature, "Second", GIT_STASH_INCLUDE_UNTRACKED));
 	cl_assert(!git_path_exists("stash/two.txt"));
 	cl_assert(git_path_exists("stash/zero.txt"));
 
 	cl_git_mkfile("stash/three.txt", "content\n");
-	cl_git_pass(git_stash_save(&oid, repo, signature, "Third", GIT_STASH_INCLUDE_UNTRACKED));
+	cl_git_pass(git_stash_save(
+		&oid, repo, signature, "Third", GIT_STASH_INCLUDE_UNTRACKED));
 	cl_assert(!git_path_exists("stash/three.txt"));
 	cl_assert(git_path_exists("stash/zero.txt"));
-
-	git_index_free(index);
 }
 
 void test_stash_drop__cannot_drop_a_non_existing_stashed_state(void)
@@ -160,7 +162,7 @@ void test_stash_drop__dropping_the_top_stash_updates_the_stash_reference(void)
 	retrieve_top_stash_id(&oid);
 
 	cl_git_pass(git_revparse_single(&next_top_stash, repo, "stash@{1}"));
-	cl_assert_equal_i(false, git_oid_cmp(&oid, git_object_id(next_top_stash)) == 0);
+	cl_assert(git_oid_cmp(&oid, git_object_id(next_top_stash)) != 0);
 
 	cl_git_pass(git_stash_drop(repo, 0));
 
diff --git a/tests-clar/stash/save.c b/tests-clar/stash/save.c
index bb35a3d..035b622 100644
--- a/tests-clar/stash/save.c
+++ b/tests-clar/stash/save.c
@@ -241,7 +241,7 @@ void test_stash_save__stashing_updates_the_reflog(void)
 void test_stash_save__cannot_stash_when_there_are_no_local_change(void)
 {
 	git_index *index;
-	git_oid commit_oid, stash_tip_oid;
+	git_oid stash_tip_oid;
 
 	cl_git_pass(git_repository_index(&index, repo));
 
@@ -251,8 +251,7 @@ void test_stash_save__cannot_stash_when_there_are_no_local_change(void)
 	 */
 	cl_git_pass(git_index_add_bypath(index, "what"));
 	cl_git_pass(git_index_add_bypath(index, "who"));
-	cl_git_pass(git_index_write(index));
-	commit_staged_files(&commit_oid, index, signature);
+	cl_repo_commit_from_index(NULL, repo, signature, 0, "Initial commit");
 	git_index_free(index);
 
 	cl_assert_equal_i(GIT_ENOTFOUND,
diff --git a/tests-clar/stash/stash_helpers.c b/tests-clar/stash/stash_helpers.c
index f462a13..06b63f1 100644
--- a/tests-clar/stash/stash_helpers.c
+++ b/tests-clar/stash/stash_helpers.c
@@ -2,38 +2,8 @@
 #include "fileops.h"
 #include "stash_helpers.h"
 
-void commit_staged_files(
-	git_oid *commit_oid,
-	git_index *index,
-	git_signature *signature)
-{
-	git_tree *tree;
-	git_oid tree_oid;
-	git_repository *repo;
-
-	repo = git_index_owner(index);
-
-	cl_git_pass(git_index_write_tree(&tree_oid, index));
-
-	cl_git_pass(git_tree_lookup(&tree, repo, &tree_oid));
-
-	cl_git_pass(git_commit_create_v(
-		commit_oid,
-		repo,
-		"HEAD",
-		signature,
-		signature,
-		NULL,
-		"Initial commit",
-		tree,
-		0));
-
-	git_tree_free(tree);
-}
-
 void setup_stash(git_repository *repo, git_signature *signature)
 {
-	git_oid commit_oid;
 	git_index *index;
 
 	cl_git_pass(git_repository_index(&index, repo));
@@ -50,9 +20,8 @@ void setup_stash(git_repository *repo, git_signature *signature)
 	cl_git_pass(git_index_add_bypath(index, "how"));
 	cl_git_pass(git_index_add_bypath(index, "who"));
 	cl_git_pass(git_index_add_bypath(index, ".gitignore"));
-	cl_git_pass(git_index_write(index));
 
-	commit_staged_files(&commit_oid, index, signature);
+	cl_repo_commit_from_index(NULL, repo, signature, 0, "Initial commit");
 
 	cl_git_rewritefile("stash/what", "goodbye\n");			/* dd7e1c6f0fefe118f0b63d9f10908c460aa317a6 */
 	cl_git_rewritefile("stash/how", "not so small and\n");	/* e6d64adb2c7f3eb8feb493b556cc8070dca379a3 */
diff --git a/tests-clar/stash/stash_helpers.h b/tests-clar/stash/stash_helpers.h
index bb7fec4..7c3e13d 100644
--- a/tests-clar/stash/stash_helpers.h
+++ b/tests-clar/stash/stash_helpers.h
@@ -1,8 +1,3 @@
 void setup_stash(
 	git_repository *repo,
 	git_signature *signature);
-
-void commit_staged_files(
-	git_oid *commit_oid,
-	git_index *index,
-	git_signature *signature);
\ No newline at end of file
diff --git a/tests-clar/status/worktree.c b/tests-clar/status/worktree.c
index be7398c..135a958 100644
--- a/tests-clar/status/worktree.c
+++ b/tests-clar/status/worktree.c
@@ -632,35 +632,12 @@ void test_status_worktree__conflicted_item(void)
 
 static void stage_and_commit(git_repository *repo, const char *path)
 {
-	git_oid tree_oid, commit_oid;
-	git_tree *tree;
-	git_signature *signature;
 	git_index *index;
 
 	cl_git_pass(git_repository_index(&index, repo));
 	cl_git_pass(git_index_add_bypath(index, path));
-	cl_git_pass(git_index_write(index));
-
-	cl_git_pass(git_index_write_tree(&tree_oid, index));
+	cl_repo_commit_from_index(NULL, repo, NULL, 1323847743, "Initial commit\n");
 	git_index_free(index);
-
-	cl_git_pass(git_tree_lookup(&tree, repo, &tree_oid));
-
-	cl_git_pass(git_signature_new(&signature, "nulltoken", "emeric.fermas@gmail.com", 1323847743, 60));
-
-	cl_git_pass(git_commit_create_v(
-		&commit_oid,
-		repo,
-		"HEAD",
-		signature,
-		signature,
-		NULL,
-		"Initial commit\n\0",
-		tree,
-		0));
-
-	git_tree_free(tree);
-	git_signature_free(signature);
 }
 
 static void assert_ignore_case(
diff --git a/tests-clar/stress/diff.c b/tests-clar/stress/diff.c
index 0524aa1..1d31973 100644
--- a/tests-clar/stress/diff.c
+++ b/tests-clar/stress/diff.c
@@ -54,27 +54,9 @@ static void test_with_many(int expected_new)
 
 	git_diff_list_free(diff);
 
-	{
-		git_object *parent;
-		git_signature *sig;
-		git_oid tree_id, commit_id;
-		git_reference *ref;
-
-		cl_git_pass(git_index_write_tree(&tree_id, index));
-		cl_git_pass(git_tree_lookup(&new_tree, g_repo, &tree_id));
-
-		cl_git_pass(git_revparse_ext(&parent, &ref, g_repo, "HEAD"));
-		cl_git_pass(git_signature_new(
-			&sig, "Sm Test", "sm@tester.test", 1372350000, 480));
-
-		cl_git_pass(git_commit_create_v(
-			&commit_id, g_repo, git_reference_name(ref), sig, sig,
-			NULL, "yoyoyo", new_tree, 1, parent));
-
-		git_object_free(parent);
-		git_reference_free(ref);
-		git_signature_free(sig);
-	}
+	cl_repo_commit_from_index(NULL, g_repo, NULL, 1372350000, "yoyoyo");
+	cl_git_pass(git_revparse_single(
+		(git_object **)&new_tree, g_repo, "HEAD^{tree}"));
 
 	cl_git_pass(git_diff_tree_to_tree(
 		&diff, g_repo, tree, new_tree, &diffopts));