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Running tests locally

Running basic tests (gtest binaries)

Windows

  1. Build
  2. Set the test as the startup project and press F5 to compile it.
  3. Or in a cmd window, run the test of interest in src\chrome\Debug, e.g. src\chrome\Debug\base_unittests.exe

Linux

  1. cd src/
  2. Build
  3. Run the test of interest, e.g. ./out/Debug/base_unittests

Many unit tests create a chromium UI, which means they need the ability to create a visible window. To run these tests remotely in a terminal, or to keep them from opening windows in your current desktop session, you can run tests inside Xvfb. See "Running in headless mode" below.

Chromium OS

You can't run browser tests or unit tests on actual Chrome OS devices or from within the cros chrome-sdk shell; instead, run them on a Linux system using a build directory with target_os="chromeos".

  1. gn gen out/Debug_chromeos/ -args='is_debug=true target_os="chromeos"'
  2. autoninja -C out/Debug_chromeos/<test target> (for instance, <test target> might be extensions_browsertests or base_unittests)
  3. out/Debug_chromeos/<test target> (for instance, out/Debug_chromeos/extensions_browsertests)

Mac

  1. Build the tests: ninja -C out/{Debug,Release} {test_target}
  2. Run the appropriate test target: ./out/{Debug,Release}/{test_target}

Running a particular subtest

The above test executables are built with gtest, so they accept command line arguments to filter which sub-tests to run. For instance, base_unittests --gtest_filter=FileUtilTest.*

Making tests show visible output

Tests that create a visible window do not draw anything into the window by default, in order to run the test faster (with exception of tests that verify pixel output). To force tests to draw visible pixels for debugging, you can use the --enable-pixel-output-in-tests command-line flag. This can be used for both unit tests and browser tests.

Web tests

Blink has a large suite of tests that typically verify a page is laid out properly. We use them to verify much of the code that runs within a Chromium renderer. To run these tests, build the blink_tests target and then run third_party/blink/tools/run_web_tests.py --debug .

More information about running web tests or fixing web tests can be found on the Web Tests page.

Unit tests and Browser tests

Most top-level directories of src/ have a unit test build target, such as content_unittests for content/, cc_unittests for cc/, and components_unittests for components/

There is also the fallback unit_tests target for unit tests built on top of the full chrome stack.

Unit tests verify some part of the chromium code base in an isolated test environment, and are usually found in files with a _unittest.cc suffix. Browser tests run a full browser, and then execute a test inside the browser instance, and are usually found in files with a _browsertest.cc suffix. There is more information on browser tests here. To add a new test, you will generally find a similar test and clone it. If you can, strongly prefer writing a unit test over a browser test as they are generally faster and more reliable.

Get dumps for Chromium crashes on Windows

Before running the tests, make sure to run crash_service.exe. We use this program to intercept crashes in chromium and write a crash dump in the Crash Reports folder under the User Data directory of your chromium profile.

If you also want crash_service.exe to intercept crashes for your normal Google Chrome or Chromium build, add the flag --noerrdialogs.

You can also use the flag --enable-dcheck to get assertion errors in release mode.

Running in headless mode with --ozone-platform or xvfb

When ssh-ed in to a machine, you don't have a display connected, which means that you normally can't run tests. Some tests don't need to draw to the screen, and for them you can simply add --ozone-platform=headless to your command line. For the others, you can run tests in headless mode with xvfb (X Virtual Frame Buffer). There are multiple ways to run tests with xvfb!

Example with unittests and testing/xvfb.py (note: you will need to install xcompmgr, although this is done as part of install-build-deps.py)

testing/xvfb.py out/Default/components_unittests

Example with browser tests and running Xvfb and setting the DISPLAY env variable.

Xvfb.py :100 -screen 0 1600x1200x24 &
DISPLAY=localhost:100 out/Default/browser_tests

Third example, with xvfb-run:

xvfb-run -s "-screen 0 1024x768x24" out/Default/content_unittests

Run tests 5x faster on gLinux

Browser tests on gLinux start up extremely slowly due to idiosyncratic NSS configurations. If you need to regularly run browser tests on gLinux, consider using the run_with_dummy_home.py helper script:

testing/run_with_dummy_home.py testing/xvfb.py out/Default/browser_tests

This can speed tests up by 5x or more.