Update GIDSignInTest to correctly setUp and tearDown NSUserDefaults (#527)

Author: camden-king

GoogleSignIn/Tests/Unit/GIDSignInTest.m

@@ -268,10 +268,8 @@ @interface GIDSignInTest : XCTestCase {
   // Status returned by saveAuthorization:toKeychainForName:
   BOOL _saveAuthorizationReturnValue;
 
-#if TARGET_OS_IOS && !TARGET_OS_MACCATALYST
   // Test userDefaults for use with `GIDAppCheck`
   NSUserDefaults *_testUserDefaults;
-#endif // TARGET_OS_IOS && !TARGET_OS_MACCATALYST
 }
 @end
 
@@ -337,15 +335,12 @@ - (void)setUp {
   [_fakeMainBundle fakeAllSchemesSupported];
 
   // Object under test
-  [[NSUserDefaults standardUserDefaults] setBool:YES forKey:kAppHasRunBeforeKey];
+  _testUserDefaults = [[NSUserDefaults alloc] initWithSuiteName:kUserDefaultsSuiteName];
+  [_testUserDefaults setBool:YES forKey:kAppHasRunBeforeKey];
 
   _signIn = [[GIDSignIn alloc] initWithKeychainStore:_keychainStore];
   _hint = nil;
 
-#if TARGET_OS_IOS && !TARGET_OS_MACCATALYST
-  _testUserDefaults = [[NSUserDefaults alloc] initWithSuiteName:kUserDefaultsSuiteName];
-#endif // TARGET_OS_IOS && !TARGET_OS_MACCATALYST
-
   __weak GIDSignInTest *weakSelf = self;
   _completion = ^(GIDSignInResult *_Nullable signInResult, NSError * _Nullable error) {
     GIDSignInTest *strongSelf = weakSelf;
@@ -372,11 +367,7 @@ - (void)tearDown {
   OCMVerifyAll(_presentingWindow);
 #endif // TARGET_OS_IOS || TARGET_OS_MACCATALYST
 
-  [[NSUserDefaults standardUserDefaults] removeObjectForKey:kAppHasRunBeforeKey];
-#if TARGET_OS_IOS && !TARGET_OS_MACCATALYST
-  [_testUserDefaults removeObjectForKey:kGIDAppCheckPreparedKey];
-  [_testUserDefaults removeSuiteNamed:kUserDefaultsSuiteName];
-#endif // TARGET_OS_IOS && !TARGET_OS_MACCATALYST
+  [_testUserDefaults removePersistentDomainForName:kUserDefaultsSuiteName];
 
   [_fakeMainBundle stopFaking];
   [super tearDown];