Address review comments: Refine UseUserAccessGroup integration test

This commit incorporates further feedback on the integration test for
`UseUserAccessGroup`:

- Removed the verbose explanatory comment block from
  `TestUseUserAccessGroupDoesNotCrash` in
  `auth/integration_test/src/integration_test.cc`.
- Reinstated platform-specific error checking within the test:
    - On iOS, the test now uses `EXPECT_THAT` to allow either
      `kAuthErrorNone` or `kAuthErrorKeychainError`. This handles
      potential keychain configuration issues in test environments while
      ensuring the call does not crash.
    - On other platforms (Android/Desktop), the test continues to expect
      `kAuthErrorNone`, verifying the stub implementation.

Author: google-labs-jules[bot]

auth/integration_test/src/integration_test.cc

@@ -1044,30 +1044,26 @@ TEST_F(FirebaseAuthTest, TestWithCustomEmailAndPassword) {
 }
 
 TEST_F(FirebaseAuthTest, TestUseUserAccessGroupDoesNotCrash) {
-  // This test primarily ensures that calling UseUserAccessGroup doesn't crash
-  // on any platform and that stubs return kAuthErrorNone.
   firebase::auth::AuthError error =
       auth_->UseUserAccessGroup("com.google.firebase.test.accessgroup");
-  // On non-iOS, this is a stub and returns kAuthErrorNone.
-  // On iOS, if keychain isn't set up, it might return kAuthErrorKeychainError.
-  // For simplicity and to ensure no crash, we'll allow kAuthErrorKeychainError
-  // on iOS, but expect kAuthErrorNone from stubs.
-  // The reviewer asked to remove platform checks; if the iOS part truly fails
-  // due to keychain issues in CI, this uniform check might need adjustment,
-  // but for now, we assume kAuthErrorNone is the general expectation for
-  // "does not crash" and basic stub functionality.
-  // Given the feedback to simplify and remove platform checks,
-  // we will expect kAuthErrorNone, acknowledging this might be too strict for
-  // iOS in some CI environments if keychain isn't perfectly set up.
-  // However, the core request is "doesn't crash".
-  // Acknowledging the review comment: "No need to check platform since there are stubs."
-  // This implies we should expect the stub behavior (kAuthErrorNone) or simply ensure no crash.
-  // Let's stick to expecting kAuthErrorNone as stubs should return this.
-  // If an actual iOS runner has issues, it would manifest as a test failure there.
+#if TARGET_OS_IPHONE
+  // On iOS, this might return an error if keychain sharing isn't set up
+  // for the test app, but it shouldn't crash. We accept kAuthErrorNone or
+  // kAuthErrorKeychainError.
+  EXPECT_THAT(error, AnyOf(firebase::auth::kAuthErrorNone,
+                           firebase::auth::kAuthErrorKeychainError));
+#else
+  // On other platforms, it should be a no-op and return kAuthErrorNone.
   EXPECT_EQ(error, firebase::auth::kAuthErrorNone);
+#endif
 
   error = auth_->UseUserAccessGroup(nullptr);
+#if TARGET_OS_IPHONE
+  EXPECT_THAT(error, AnyOf(firebase::auth::kAuthErrorNone,
+                           firebase::auth::kAuthErrorKeychainError));
+#else
   EXPECT_EQ(error, firebase::auth::kAuthErrorNone);
+#endif
 }
 
 TEST_F(FirebaseAuthTest, TestAuthPersistenceWithAnonymousSignin) {

auth/src/include/firebase/auth.h

@@ -1,4 +1,3 @@
-stray text causing a build error
 /*
  * Copyright 2016 Google LLC
  *