GDT tests: Xcode 12 fixes (#6469)

* GDT tests: Xcode 12 fixes

* Silent unused warnings for weakSelf vars (for Xcode 12)

Author: maksymmalyhin

GoogleDataTransport/GDTCCTTests/Unit/GDTCCTUploaderTest.m

@@ -360,7 +360,7 @@ - (void)testStorageSelectorWhenConditionsHighPriority {
   [self assertStorageSelectorWithCondition:GDTCORUploadConditionHighPriority
                            validationBlock:^(GDTCORStorageEventSelector *_Nullable eventSelector,
                                              NSDate *expiration) {
-                             id self = weakSelf;
+                             __unused id self = weakSelf;
                              XCTAssertLessThan([expiration timeIntervalSinceNow], 600);
                              XCTAssertEqual(eventSelector.selectedTarget, kGDTCORTargetTest);
                              XCTAssertNil(eventSelector.selectedEventIDs);
@@ -375,7 +375,7 @@ - (void)testStorageSelectorWhenConditionsMobileData {
       assertStorageSelectorWithCondition:GDTCORUploadConditionMobileData
                          validationBlock:^(GDTCORStorageEventSelector *_Nullable eventSelector,
                                            NSDate *expiration) {
-                           id self = weakSelf;
+                           __unused id self = weakSelf;
                            XCTAssertLessThan([expiration timeIntervalSinceNow], 600);
                            XCTAssertEqual(eventSelector.selectedTarget, kGDTCORTargetTest);
                            XCTAssertNil(eventSelector.selectedEventIDs);
@@ -393,7 +393,7 @@ - (void)testStorageSelectorWhenConditionsWifiData {
       assertStorageSelectorWithCondition:GDTCORUploadConditionWifiData
                          validationBlock:^(GDTCORStorageEventSelector *_Nullable eventSelector,
                                            NSDate *expiration) {
-                           id self = weakSelf;
+                           __unused id self = weakSelf;
                            XCTAssertLessThan([expiration timeIntervalSinceNow], 600);
                            XCTAssertEqual(eventSelector.selectedTarget, kGDTCORTargetTest);
                            XCTAssertNil(eventSelector.selectedEventIDs);
@@ -582,7 +582,7 @@ - (XCTestExpectation *)expectStorageHasEventsForTarget:(GDTCORTarget)expectedTar
   __weak __auto_type weakSelf = self;
   self.testStorage.hasEventsForTargetHandler =
       ^(GDTCORTarget target, GDTCCTTestStorageHasEventsCompletion _Nonnull completion) {
-        __auto_type self = weakSelf;
+        __unused __auto_type self = weakSelf;
         [expectation fulfill];
         XCTAssertEqual(target, expectedTarget);
         completion(hasEvents);

GoogleDataTransport/GDTCORTests/Unit/GDTCORTransformerTest.m

@@ -173,15 +173,15 @@ - (void)testWriteEventWithTransformersThatCreateANewEvent {
 
   self.fakeApplication.beginTaskHandler =
       ^GDTCORBackgroundIdentifier(NSString *_Nonnull name, dispatch_block_t _Nonnull handler) {
-        __auto_type self = weakSelf;
+        __unused __auto_type self = weakSelf;
         XCTAssertEqualObjects(expectedName, name);
 
         [beginExpectation fulfill];
         return taskID;
       };
 
   self.fakeApplication.endTaskHandler = ^(GDTCORBackgroundIdentifier endTaskID) {
-    __auto_type self = weakSelf;
+    __unused __auto_type self = weakSelf;
     XCTAssert(endTaskID == taskID);
     [endExpectation fulfill];
   };