Add git_commit_amend API

This adds an API to amend an existing commit, basically a shorthand
for creating a new commit filling in missing parameters from the
values of an existing commit.  As part of this, I also added a new
"sys" API to create a commit using a callback to get the parents.
This allowed me to rewrite all the other commit creation APIs so
that temporary allocations are no longer needed.

1 files changed, 76 insertions, 0 deletions

diff --git a/tests/object/commit/commitstagedfile.c b/tests/object/commit/commitstagedfile.c
index fbeeccbbd..3e7b3c02c 100644
--- a/tests/object/commit/commitstagedfile.c
+++ b/tests/object/commit/commitstagedfile.c
@@ -132,3 +132,79 @@ void test_object_commit_commitstagedfile__generate_predictable_object_ids(void)
 	git_tree_free(tree);
 	git_index_free(index);
 }
+
+static void assert_commit_tree_has_n_entries(git_commit *c, int count)
+{
+	git_tree *tree;
+	cl_git_pass(git_commit_tree(&tree, c));
+	cl_assert_equal_i(count, git_tree_entrycount(tree));
+	git_tree_free(tree);
+}
+
+static void assert_commit_is_head_(git_commit *c, const char *file, int line)
+{
+	git_commit *head;
+	cl_git_pass(git_revparse_single((git_object **)&head, repo, "HEAD"));
+	clar__assert(git_oid_equal(git_commit_id(c), git_commit_id(head)), file, line, "Commit is not the HEAD", NULL, 1);
+	git_commit_free(head);
+}
+#define assert_commit_is_head(C) assert_commit_is_head_((C),__FILE__,__LINE__)
+
+void test_object_commit_commitstagedfile__amend_commit(void)
+{
+	git_index *index;
+	git_oid old_oid, new_oid, tree_oid;
+	git_commit *old_commit, *new_commit;
+	git_tree *tree;
+
+	/* make a commit */
+
+	cl_git_mkfile("treebuilder/myfile", "This is a file\n");
+	cl_git_pass(git_repository_index(&index, repo));
+	cl_git_pass(git_index_add_bypath(index, "myfile"));
+	cl_repo_commit_from_index(&old_oid, repo, NULL, 0, "first commit");
+
+	cl_git_pass(git_commit_lookup(&old_commit, repo, &old_oid));
+
+	cl_assert_equal_i(0, git_commit_parentcount(old_commit));
+	assert_commit_tree_has_n_entries(old_commit, 1);
+	assert_commit_is_head(old_commit);
+
+	/* let's amend the message of the HEAD commit */
+
+	cl_git_pass(git_commit_amend(
+		&new_oid, old_commit, "HEAD", NULL, NULL, NULL, "Initial commit", NULL));
+
+	cl_git_pass(git_commit_lookup(&new_commit, repo, &new_oid));
+
+	cl_assert_equal_i(0, git_commit_parentcount(new_commit));
+	assert_commit_tree_has_n_entries(new_commit, 1);
+	assert_commit_is_head(new_commit);
+
+	git_commit_free(old_commit);
+	old_commit = new_commit;
+
+	/* let's amend the tree of that last commit */
+
+	cl_git_mkfile("treebuilder/anotherfile", "This is another file\n");
+	cl_git_pass(git_index_add_bypath(index, "anotherfile"));
+	cl_git_pass(git_index_write_tree(&tree_oid, index));
+	cl_git_pass(git_tree_lookup(&tree, repo, &tree_oid));
+	cl_assert_equal_i(2, git_tree_entrycount(tree));
+
+	cl_git_pass(git_commit_amend(
+		&new_oid, old_commit, "HEAD", NULL, NULL, NULL, "Initial commit", tree));
+	git_tree_free(tree);
+
+	cl_git_pass(git_commit_lookup(&new_commit, repo, &new_oid));
+
+	cl_assert_equal_i(0, git_commit_parentcount(new_commit));
+	assert_commit_tree_has_n_entries(new_commit, 2);
+	assert_commit_is_head(new_commit);
+
+	/* cleanup */
+
+	git_commit_free(old_commit);
+	git_commit_free(new_commit);
+	git_index_free(index);
+}