Automated testing for Chrome for iOS

See the instructions for how to check out and build Chromium for iOS.

Automated testing is a crucial part of ensuring the quality of Chromium.

Unit testing

Unit testing is done via gtests. To run a unit test, simply run the test target (ending in _unittest).

Integration testing

EarlGrey (EG2) is the integration testing framework used by Chromium for iOS.

Writing EarlGrey tests

Before you start

Creating test files and writing EG2 tests

  1. EG2 test files are ended with, and usually located within the same directory of the UI code you wish to test.

  2. Basic imports of a EG2 test file:

    • You’ll have to include:
    #import "ios/chrome/test/earl_grey/chrome_test_case.h"
    • You’ll most likely find util functions in these files helpful.
    #import "ios/chrome/test/earl_grey/chrome_earl_grey.h"
    #import "ios/chrome/test/earl_grey/chrome_earl_grey_ui.h"
    #import "ios/chrome/test/earl_grey/chrome_matchers.h"
    • Beside these, directly import an EG2 header for an EG2 API you are using.
  3. TestCase/testMethods definitions. Create SomeGreatTestCase as a subclass of ChromeTestCase. Create test methods, eg -(void)testMyGreatUIFeature {...}, and put UI actions within the test methods.

    • Put your setup and tear down code for the TestCase in +(void)setUpForTestCase and +tearDown. These will run once before and after all tests for the test class.
    • Put your setup and tear down code for each test method in -(void)setUp and -(void)tearDown. These will run before and after every -(void)testMethod in the file.
  4. Writing test contents. See the chrome helpers (imports in 2.) as well as EarlGrey APIs to write a UI action/assertion in your testMethod.

Interacting with the app in a test

Relaunch app with different flags

In EG2 tests, the test process launches the host app process at the beginning, then runs UI actions/assertions in the app. To pass args or feature flags to the app at initial launching, or relaunch the app in the middle of your test, see this AppLaunchManager API.

Accessing app internals

EG2 test targets are built with test-related code but without app code.

To access anything from the app side, use an “app interface”. App interface is implemented as a class that lives in the app process, but can be accessed in the test process through eDO. You can include the header in your test side code and call class methods of the interface class. The methods will execute code in the app process and can return basic Objective-C types. See this Example of App Interface.

See eg_test_support+eg2 (test side utilities) and eg_app_support+eg2 (app side utilities) targets in files to learn how test utilities are organized in targets. If you added an app side helper (app interface), you’ll also need to include your new eg_app_support+eg2 target in //ios/chrome/test/earl_grey/’s eg_app_support+eg2 target. (Example CL adding App Interface).

Note that if you create an App interface, you can’t build the app interface class in your eg2_tests target, but you need to include and refer to it. To satisfy the linker, you'll need to create a file with the following content in it and build it as a dependency of your tests that use the app interface.

#import "ios_internal/chrome/test/earl_grey2/my_test_app_interface.h"

#import <TestLib/EarlGreyImpl/EarlGrey.h>

#if !defined(__has_feature) || !__has_feature(objc_arc)
#error "This file requires ARC support."


If you don‘t you’ll get linker errors that read like “Undefined symbols for architecture… MyTestAppInterface”

Creating test targets and adding the target to test suites

  1. Create a test target. Add a target(source_set) named “eg2_tests” into the closest file. Put the test file into the sources array and put the targets containing headers used in your test file into deps array. This is to organize test source files and dependencies so that the GN build system can correctly build the test module. The skeleton of the target:
source_set("eg2_tests") {
  configs += [
  testonly = true
  sources = [
  deps = [
  frameworks = [ "UIKit.framework" ]
  1. Include your test target in the deps array of a suitable suite in //src/ios/chrome/test/earl_grey2/
  2. Optional: If you feel like your new test should be in a new suite, or you want to delete an existing suite to make tests better organized, you’ll need to change the suites in //src/ios/chrome/test/earl_grey2/ in the format of existing ones. (Do not forget to config the bots so the new suite can run in infra.)
  3. Ensure your dependencies are correct.
$ gn gen --check out/Debug-iphonesimulator

Running EarlGrey tests

EarlGrey tests are based on Apple's XCUITest.

Running tests from Xcode

  1. If you added a new test file / suite, run gclient runhooks to sync for the list of tests in Xcode.
  2. Change the scheme to “ios_chrome_eg2test”. Create and select the simulator you wish to use.
  3. You may run a test suite(module), TestCase or testMethod in test navigator. Xcode will build the targets and run the test(s) you choose. Alternatively, use ⌘+U to run all the tests. See Apple's Running Tests and Viewing Results.

Running from the command-line

EG2 tests can run in the command line with test runner scripts. You’ll need to build the targets before running tests in cmd. This is used by continuous integration infra and thus not user friendly. Running UI tests directly in Xcode is recommended.

Important notes:

  • The test runner can invoke mac_toolchain to install a new Xcode of the version specified to the path specified. You may want to choose a different path from your daily use Xcode.
  • If test_cases is empty in --args-json, all tests will run. Specifying a testMethod to run is currently not supported in the test runner.


    {"test_args": [], "xctest": false, "test_cases": ["ReadingListTestCase"],
    "restart": false, "xcode_parallelization": true, "xcodebuild_device_runner":
    iPad (6th generation)

The invocation args are logged. You can find the latest arg format at the beginning of stdout from an infra test shard if the above doesn't work.