tests: add test suite for opening submodules

tests/submodule/open.c

+#include "clar_libgit2.h"
+#include "submodule_helpers.h"
+#include "path.h"
+
+static git_repository *g_parent;
+static git_repository *g_child;
+static git_submodule *g_module;
+
+void test_submodule_open__initialize(void)
+{
+	g_parent = setup_fixture_submod2();
+}
+
+void test_submodule_open__cleanup(void)
+{
+	git_submodule_free(g_module);
+	git_repository_free(g_child);
+	cl_git_sandbox_cleanup();
+	g_parent = NULL;
+	g_child = NULL;
+	g_module = NULL;
+}
+
+static void assert_sm_valid(git_repository *parent, git_repository *child, const char *sm_name)
+{
+	git_buf expected = GIT_BUF_INIT, actual = GIT_BUF_INIT;
+
+	/* assert working directory */
+	cl_git_pass(git_buf_joinpath(&expected, git_repository_workdir(parent), sm_name));
+	cl_git_pass(git_path_prettify_dir(&expected, expected.ptr, NULL));
+	cl_git_pass(git_buf_sets(&actual, git_repository_workdir(child)));
+	cl_git_pass(git_path_prettify_dir(&actual, actual.ptr, NULL));
+	cl_assert_equal_s(expected.ptr, actual.ptr);
+
+	git_buf_clear(&expected);
+	git_buf_clear(&actual);
+
+	/* assert common directory */
+	cl_git_pass(git_buf_joinpath(&expected, git_repository_commondir(parent), "modules"));
+	cl_git_pass(git_buf_joinpath(&expected, expected.ptr, sm_name));
+	cl_git_pass(git_path_prettify_dir(&expected, expected.ptr, NULL));
+	cl_git_pass(git_buf_sets(&actual, git_repository_commondir(child)));
+	cl_git_pass(git_path_prettify_dir(&actual, actual.ptr, NULL));
+	cl_assert_equal_s(expected.ptr, actual.ptr);
+
+	/* assert git directory */
+	cl_git_pass(git_buf_sets(&actual, git_repository_path(child)));
+	cl_git_pass(git_path_prettify_dir(&actual, actual.ptr, NULL));
+	cl_assert_equal_s(expected.ptr, actual.ptr);
+
+	git_buf_free(&expected);
+	git_buf_free(&actual);
+}
+
+void test_submodule_open__opening_via_lookup_succeeds(void)
+{
+	cl_git_pass(git_submodule_lookup(&g_module, g_parent, "sm_unchanged"));
+	cl_git_pass(git_submodule_open(&g_child, g_module));
+	assert_sm_valid(g_parent, g_child, "sm_unchanged");
+}
+
+void test_submodule_open__direct_open_succeeds(void)
+{
+	git_buf path = GIT_BUF_INIT;
+
+	cl_git_pass(git_buf_joinpath(&path, git_repository_workdir(g_parent), "sm_unchanged"));
+	cl_git_pass(git_repository_open(&g_child, path.ptr));
+	assert_sm_valid(g_parent, g_child, "sm_unchanged");
+
+	git_buf_free(&path);
+}