Update submodule ignore rule API

ObjectiveGit/GTSubmodule.h

@@ -60,9 +60,7 @@ NS_ASSUME_NONNULL_BEGIN
 @property (nonatomic, strong, readonly) GTRepository *parentRepository;
 
 /// The current ignore rule for this submodule.
-///
-/// Setting this property will only update the rule in memory, not on disk.
-@property (nonatomic, assign) GTSubmoduleIgnoreRule ignoreRule;
+@property (nonatomic, readonly, assign) GTSubmoduleIgnoreRule ignoreRule;
 
 /// The OID that the submodule is pinned to in the parent repository's index.
 ///
@@ -111,6 +109,16 @@ NS_ASSUME_NONNULL_BEGIN
 /// Returns whether reloading succeeded.
 - (BOOL)reload:(NSError **)error;
 
+/// Write a new ignore rule to disk and get the resulting submodule. The
+/// receiver will not have the new ignore rule. To update the receiver, call
+/// `-reload:`.
+///
+/// ignoreRule - The ignore rule.
+/// error      - The error if one occurred.
+///
+/// Returns the updated submodule or nil if an error occurred.
+- (nullable GTSubmodule *)submoduleByUpdatingIgnoreRule:(GTSubmoduleIgnoreRule)ignoreRule error:(NSError **)error;
+
 /// Synchronizes the submodule repository's configuration files with the settings
 /// from the parent repository.
 ///
@@ -124,11 +132,17 @@ NS_ASSUME_NONNULL_BEGIN
 /// Returns the opened repository, or nil if an error occurs.
 - (nullable GTRepository *)submoduleRepository:(NSError **)error;
 
-/// Determines the status for the submodule.
-///
-/// Returns the status, or `GTSubmoduleStatusUnknown` if an error occurs.
+/// Calls `-statusWithIgnoreRule:error:` with the submodule's ignore rule.
 - (GTSubmoduleStatus)status:(NSError **)error;
 
+/// Determine the status for the submodule using the given ignore rule.
+///
+/// ignoreRule - The ignore rule to use in calculating status.
+/// error      - The error if one occurred.
+///
+/// Returns the status or `GTSubmoduleStatusUnknown` if an error occurred.
+- (GTSubmoduleStatus)statusWithIgnoreRule:(GTSubmoduleIgnoreRule)ignoreRule error:(NSError **)error;
+
 /// Initializes the submodule by copying its information into the parent
 /// repository's `.git/config` file. This is equivalent to `git submodule init`
 /// on the command line.

ObjectiveGit/GTSubmodule.m

@@ -25,12 +25,16 @@ - (GTSubmoduleIgnoreRule)ignoreRule {
 	return (GTSubmoduleIgnoreRule)git_submodule_ignore(self.git_submodule);
 }
 
-- (void)setIgnoreRule:(GTSubmoduleIgnoreRule)ignoreRule {
-	git_submodule_set_ignore(self.parentRepository.git_repository, git_submodule_name(self.git_submodule), (git_submodule_ignore_t)ignoreRule);
+- (GTSubmodule *)submoduleByUpdatingIgnoreRule:(GTSubmoduleIgnoreRule)ignoreRule error:(NSError **)error {
+	int result = git_submodule_set_ignore(self.parentRepository.git_repository, git_submodule_name(self.git_submodule), (git_submodule_ignore_t)ignoreRule);
+	if (result != GIT_OK) {
+		if (error != NULL) {
+			*error = [NSError git_errorFor:result description:@"Couldn't set submodule ignore rule."];
+		}
+		return nil;
+	}
 
-	// The docs for `git_submodule_set_ignore` note "This does not affect any
-	// currently-loaded instances." So we need to reload.
-	git_submodule_reload(self.git_submodule, 0);
+	return [self.parentRepository submoduleWithName:self.name error:error];
 }
 
 - (GTOID *)indexOID {
@@ -98,9 +102,9 @@ - (instancetype)initWithGitSubmodule:(git_submodule *)submodule parentRepository
 
 #pragma mark Inspection
 
-- (GTSubmoduleStatus)status:(NSError **)error {
+- (GTSubmoduleStatus)statusWithIgnoreRule:(GTSubmoduleIgnoreRule)ignoreRule error:(NSError **)error {
 	unsigned status;
-	int gitError = git_submodule_status(&status, self.parentRepository.git_repository, git_submodule_name(self.git_submodule), git_submodule_ignore(self.git_submodule));
+	int gitError = git_submodule_status(&status, self.parentRepository.git_repository, git_submodule_name(self.git_submodule), (git_submodule_ignore_t)ignoreRule);
 	if (gitError != GIT_OK) {
 		if (error != NULL) *error = [NSError git_errorFor:gitError description:@"Failed to get submodule %@ status.", self.name];
 		return GTSubmoduleStatusUnknown;
@@ -109,6 +113,10 @@ - (GTSubmoduleStatus)status:(NSError **)error {
 	return status;
 }
 
+- (GTSubmoduleStatus)status:(NSError **)error {
+	return [self statusWithIgnoreRule:self.ignoreRule error:error];
+}
+
 #pragma mark Manipulation
 
 - (BOOL)reload:(NSError **)error {
@@ -131,7 +139,7 @@ - (BOOL)sync:(NSError **)error {
 	return YES;
 }
 
-- (GTRepository *)submoduleRepository:(NSError **)error {
+- (nullable GTRepository *)submoduleRepository:(NSError **)error {
 	git_repository *repo;
 	int gitError = git_submodule_open(&repo, self.git_submodule);
 	if (gitError != GIT_OK) {

ObjectiveGitTests/GTSubmoduleSpec.m

@@ -93,6 +93,16 @@
 	expect(@(success)).to(beTruthy());
 });
 
+it(@"should update the ignore rule", ^{
+	GTSubmodule *submodule = [repo submoduleWithName:@"Test_App" error:NULL];
+	expect(submodule).notTo(beNil());
+	expect(@(submodule.ignoreRule)).to(equal(@(GTSubmoduleIgnoreNone)));
+
+	GTSubmodule *updatedSubmodule = [submodule submoduleByUpdatingIgnoreRule:GTSubmoduleIgnoreAll error:NULL];
+	expect(@(updatedSubmodule.ignoreRule)).to(equal(@(GTSubmoduleIgnoreAll)));
+	expect(@(submodule.ignoreRule)).to(equal(@(GTSubmoduleIgnoreNone)));
+});
+
 describe(@"clean, checked out submodule", ^{
 	__block GTSubmodule *submodule;
 
@@ -204,13 +214,11 @@
 	});
 
 	it(@"should honor the ignore rule", ^{
-		submodule.ignoreRule = GTSubmoduleIgnoreDirty;
-
 		GTSubmoduleStatus expectedStatus =
 			GTSubmoduleStatusExistsInHEAD | GTSubmoduleStatusExistsInIndex | GTSubmoduleStatusExistsInConfig | GTSubmoduleStatusExistsInWorkingDirectory |
 			GTSubmoduleStatusModifiedInIndex | GTSubmoduleStatusModifiedInWorkingDirectory;
 
-		expect(@([submodule status:NULL])).to(equal(@(expectedStatus)));
+		expect(@([submodule statusWithIgnoreRule:GTSubmoduleIgnoreDirty error:NULL])).to(equal(@(expectedStatus)));
 	});
 
 	it(@"should open a repository" ,^{