submodule: test unsetting config options

In addition to mapping enums to strings in the configuration, we need to
know to delete the configuration option when given the "none" or "no"
option.

tests/submodule/modify.c

@@ -128,42 +128,58 @@ void test_submodule_modify__sync(void)
 	git_submodule_free(sm3);
 }
 
-void test_submodule_modify__set_ignore(void)
+void assert_ignore_change(git_submodule_ignore_t ignore)
 {
 	git_submodule *sm;
 
-	cl_git_pass(git_submodule_set_ignore(g_repo, "sm_changed_head", GIT_SUBMODULE_IGNORE_UNTRACKED));
+	cl_git_pass(git_submodule_set_ignore(g_repo, "sm_changed_head", ignore));
 
 	cl_git_pass(git_submodule_lookup(&sm, g_repo, "sm_changed_head"));
-	cl_assert_equal_i(GIT_SUBMODULE_IGNORE_UNTRACKED, git_submodule_ignore(sm));
+	cl_assert_equal_i(ignore, git_submodule_ignore(sm));
 	git_submodule_free(sm);
 }
 
-void test_submodule_modify__set_update(void)
+void test_submodule_modify__set_ignore(void)
+{
+	assert_ignore_change(GIT_SUBMODULE_IGNORE_UNTRACKED);
+	assert_ignore_change(GIT_SUBMODULE_IGNORE_NONE);
+	assert_ignore_change(GIT_SUBMODULE_IGNORE_ALL);
+}
+
+void assert_update_change(git_submodule_update_t update)
 {
 	git_submodule *sm;
 
-	cl_git_pass(git_submodule_set_update(g_repo, "sm_changed_head", GIT_SUBMODULE_UPDATE_REBASE));
+	cl_git_pass(git_submodule_set_update(g_repo, "sm_changed_head", update));
 
 	cl_git_pass(git_submodule_lookup(&sm, g_repo, "sm_changed_head"));
-	cl_assert_equal_i(GIT_SUBMODULE_UPDATE_REBASE, git_submodule_update_strategy(sm));
+	cl_assert_equal_i(update, git_submodule_update_strategy(sm));
 	git_submodule_free(sm);
 }
 
-void test_submodule_modify__set_fetch_recurse_submodules(void)
+void test_submodule_modify__set_update(void)
+{
+	assert_update_change(GIT_SUBMODULE_UPDATE_REBASE);
+	assert_update_change(GIT_SUBMODULE_UPDATE_NONE);
+	assert_update_change(GIT_SUBMODULE_UPDATE_CHECKOUT);
+}
+
+void assert_recurse_change(git_submodule_recurse_t recurse)
 {
 	git_submodule *sm;
 
-	cl_git_pass(git_submodule_set_fetch_recurse_submodules(g_repo, "sm_changed_head", GIT_SUBMODULE_RECURSE_YES));
+	cl_git_pass(git_submodule_set_fetch_recurse_submodules(g_repo, "sm_changed_head", recurse));
 
 	cl_git_pass(git_submodule_lookup(&sm, g_repo, "sm_changed_head"));
-	cl_assert_equal_i(GIT_SUBMODULE_RECURSE_YES, git_submodule_fetch_recurse_submodules(sm));
+	cl_assert_equal_i(recurse, git_submodule_fetch_recurse_submodules(sm));
 	git_submodule_free(sm);
+}
 
-	git_submodule_set_fetch_recurse_submodules(g_repo, "sm_changed_head", GIT_SUBMODULE_RECURSE_ONDEMAND);
-	cl_git_pass(git_submodule_lookup(&sm, g_repo, "sm_changed_head"));
-	cl_assert_equal_i(GIT_SUBMODULE_RECURSE_ONDEMAND, git_submodule_fetch_recurse_submodules(sm));
-	git_submodule_free(sm);
+void test_submodule_modify__set_fetch_recurse_submodules(void)
+{
+	assert_recurse_change(GIT_SUBMODULE_RECURSE_YES);
+	assert_recurse_change(GIT_SUBMODULE_RECURSE_NO);
+	assert_recurse_change(GIT_SUBMODULE_RECURSE_ONDEMAND);
 }
 
 void test_submodule_modify__set_branch(void)