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faq.md

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FAQ

How does EarlGrey compare to Xcode 7’s UI Testing?

EarlGrey is more of a grey-box testing solution whereas Xcode’s UI Testing is completely black-box. EarlGrey runs in the same process as the app under test, so it has access to the same memory as the app. This allows for better synchronization, such as ability to wait for network requests, and allows for custom synchronization mechanisms (using idling resources and conditions) that aren’t possible when using Xcode’s UI Testing feature.

However, EarlGrey is unable to launch or terminate the app under test from within the test case, something that Xcode UI Testing is capable of. While EarlGrey supports many interactions, it makes use of private APIs to create and inject touches, whereas Xcode’s UI Testing feature uses public APIs.

Nonetheless, EarlGrey’s APIs are highly extensible and provide a way to write custom UI actions and assertions. The ability to search for elements (using search actions) makes test cases resilient to UI changes. For example, EarlGrey provides APIs that allow searching for elements in scrollable containers, regardless of the amount of scrolling required.

I get a crash with “Could not swizzle …”

This usually means that EarlGrey is trying to swizzle the method that it has swizzled before. This can happen if EarlGrey is being linked to more than once. Ensure that only the app under test is linking to EarlGrey and that the app has no dependencies on EarlGrey.

I see lots of “XXX is implemented in both YYY and ZZZ. One of the two will be used. Which one is undefined.” in the logs

This usually means that EarlGrey is being linked to more than once. Ensure that the app under test is linking to EarlGrey and that the app has no dependencies on EarlGrey.

Is there a way to return a specific element?

No, but there is a better alternative. Use GREYActionBlock to create a custom GREYAction and access any fields or invoke any selector on the element. For example, if you want to invoke a selector on an element, you can use syntax similar to the following:

- (void)testInvokeCustomSelectorOnElement {
  [[EarlGrey selectElementWithMatcher:grey_accessibilityID(@"id_of_element")]
      performAction:[GREYActionBlock actionWithName:@"Invoke clearStateForTest selector"
       performBlock:^(id element, NSError *__strong *errorOrNil) {
           [element doSomething];
           return YES; // Return YES for success, NO for failure.
       }
  ]];
}

How do I perform conditional actions on elements that may or may not exist in the UI hierarchy?

If you are unsure whether the element exists in the UI hierarchy, pass an NSError to the interaction and check if the error domain and code indicate that the element wasn’t found:

NSError *error;
[[EarlGrey selectElementWithMatcher:grey_accessibilityID(‘Foo")]
    performAction:grey_tap() error:&error];
if ([error.domain isEqual:kGREYInteractionErrorDomain] &&
    error.code == kGREYInteractionElementNotFoundErrorCode) {
  // Element doesn’t exist.
}

My app shows a splash screen. How can I make my test wait for the main screen?

Use GREYCondition in your test's setup method to wait for the main screen’s view controller. Here’s an example:

 (void)setUp {
  [super setUp];

  // Wait for the main view controller to become the root view controller.
  BOOL success = [[GREYCondition conditionWithName:@"Wait for main root view controller" block:^{
    id<UIApplicationDelegate> appDelegate = [UIApplication sharedApplication].delegate;
    UIViewController *rootViewController = appDelegate.window.rootViewController;
    return [rootViewController isKindOfClass:[MainViewController class]];
  }] waitWithTimeout:5];

  GREYAssertTrue(success, @"Main view controller should appear within 5 seconds.");
}

Will my test fail if I have other modal dialogs showing on top of my app?

Yes, if these dialogs belong to the app process running the test and are obscuring UI elements with which tests are interacting.

Can I use Xcode Test Navigator?

Yes. EarlGrey supports Test Navigator out-of-the-box.

Can I set debug breakpoints in the middle of a test?

Yes. You can set a breakpoint on any interaction. The breakpoint will be hit before that interaction is executed, but after all prior interactions have been executed.