fix: flaky FIRCLSSettingsTests.m (#15623)

Author: ncooke3

Crashlytics/Crashlytics/Models/FIRCLSSettings.h

@@ -30,8 +30,7 @@ NS_ASSUME_NONNULL_BEGIN
 - (instancetype)init NS_UNAVAILABLE;
 + (instancetype)new NS_UNAVAILABLE;
 - (instancetype)initWithFileManager:(FIRCLSFileManager *)fileManager
-                         appIDModel:(FIRCLSApplicationIdentifierModel *)appIDModel
-    NS_DESIGNATED_INITIALIZER;
+                         appIDModel:(FIRCLSApplicationIdentifierModel *)appIDModel;
 
 /**
  * Recreates the settings dictionary by re-reading the settings file from persistent storage. This

Crashlytics/Crashlytics/Models/FIRCLSSettings.m

@@ -40,12 +40,23 @@ @interface FIRCLSSettings ()
 
 @property(nonatomic) BOOL isCacheKeyExpired;
 
+@property(nonatomic) dispatch_queue_t deletionQueue;
+
 @end
 
 @implementation FIRCLSSettings
 
 - (instancetype)initWithFileManager:(FIRCLSFileManager *)fileManager
                          appIDModel:(FIRCLSApplicationIdentifierModel *)appIDModel {
+  return
+      [self initWithFileManager:fileManager
+                     appIDModel:appIDModel
+                  deletionQueue:dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0)];
+}
+
+- (instancetype)initWithFileManager:(FIRCLSFileManager *)fileManager
+                         appIDModel:(FIRCLSApplicationIdentifierModel *)appIDModel
+                      deletionQueue:(dispatch_queue_t)deletionQueue {
   self = [super init];
   if (!self) {
     return nil;
@@ -57,6 +68,8 @@ - (instancetype)initWithFileManager:(FIRCLSFileManager *)fileManager
   _settingsDictionary = nil;
   _isCacheKeyExpired = NO;
 
+  _deletionQueue = deletionQueue;
+
   return self;
 }
 
@@ -190,19 +203,15 @@ - (NSDictionary *)loadCacheKey {
 
 - (void)deleteCachedSettings {
   __weak FIRCLSSettings *weakSelf = self;
-#ifndef FIREBASE_IS_NIGHTLY_TESTING
-  dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
-#endif
+  dispatch_async(_deletionQueue, ^{
     __strong FIRCLSSettings *strongSelf = weakSelf;
     if ([strongSelf.fileManager fileExistsAtPath:strongSelf.fileManager.settingsFilePath]) {
       [strongSelf.fileManager removeItemAtPath:strongSelf.fileManager.settingsFilePath];
     }
     if ([strongSelf.fileManager fileExistsAtPath:strongSelf.fileManager.settingsCacheKeyPath]) {
       [strongSelf.fileManager removeItemAtPath:strongSelf.fileManager.settingsCacheKeyPath];
     }
-#ifndef FIREBASE_IS_NIGHTLY_TESTING
   });
-#endif
 
   @synchronized(self) {
     self.isCacheKeyExpired = YES;

Crashlytics/UnitTests/FIRCLSSettingsTests.m

@@ -60,6 +60,10 @@ @interface FIRCLSSettings (Testing)
 
 @property(nonatomic, strong) NSDictionary<NSString *, id> *settingsDictionary;
 
+- (instancetype)initWithFileManager:(FIRCLSFileManager *)fileManager
+                         appIDModel:(FIRCLSApplicationIdentifierModel *)appIDModel
+                      deletionQueue:(dispatch_queue_t)deletionQueue;
+
 @end
 
 @interface FIRCLSSettingsTests : XCTestCase
@@ -75,15 +79,18 @@ @implementation FIRCLSSettingsTests
 
 - (void)setUp {
   [super setUp];
-
   _fileManager = [[FIRCLSMockFileManager alloc] init];
 
   _appIDModel = [[FABMockApplicationIdentifierModel alloc] init];
   _appIDModel.buildInstanceID = FIRCLSDefaultMockBuildInstanceID;
   _appIDModel.displayVersion = FIRCLSDefaultMockAppDisplayVersion;
   _appIDModel.buildVersion = FIRCLSDefaultMockAppBuildVersion;
 
-  _settings = [[FIRCLSSettings alloc] initWithFileManager:_fileManager appIDModel:_appIDModel];
+  // Inject a higher priority queue for deletion operations to reduce flakes.
+  _settings = [[FIRCLSSettings alloc]
+      initWithFileManager:_fileManager
+               appIDModel:_appIDModel
+            deletionQueue:dispatch_get_global_queue(QOS_CLASS_USER_INTERACTIVE, 0)];
 }
 
 - (void)testDefaultSettings {
@@ -134,7 +141,7 @@ - (void)cacheSettingsWithGoogleAppID:(NSString *)googleAppID
 
   [self.settings cacheSettingsWithGoogleAppID:googleAppID currentTimestamp:currentTimestamp];
 
-  [self waitForExpectations:@[ self.fileManager.removeExpectation ] timeout:1];
+  [self waitForExpectations:@[ self.fileManager.removeExpectation ] timeout:5.0];
 }
 
 - (void)reloadFromCacheWithGoogleAppID:(NSString *)googleAppID