WebView Test Instructions

Android Instructions

Please follow the instructions at android_test_instructions.md. This guide is an extension with WebView-specific content.

Note: except where otherwise noted, all tests require a device or emulator.

Chromium-side tests

Instrumentation tests

These tests live under //android_webview/javatests/, and are mostly end-to-end (with the exception of the //android_webview/glue/ layer).

# Build
$ autoninja -C out/Default webview_instrumentation_test_apk

# Run tests (any of these commands):
$ out/Default/bin/run_webview_instrumentation_test_apk # All tests
$ out/Default/bin/run_webview_instrumentation_test_apk -f AwContentsTest#* # A particular test suite
$ out/Default/bin/run_webview_instrumentation_test_apk -f AwContentsTest#testClearCacheInQuickSuccession # A single test
$ out/Default/bin/run_webview_instrumentation_test_apk -f AwContentsTest#*Succession # Any glob pattern matching 1 or more tests

# Print both Java and C++ log messages to the console (optional):
$ adb logcat
You can optionally use ClassName.methodName instead of ClassName#methodName; the chromium test runner understands either syntax.

Java unittests

These tests live under //android_webview/junit/ and use Robolectric.

Tip: Robolectric tests run on workstation and do not need a device or emulator. These generally run much faster than on-device tests.
# Build
$ autoninja -C out/Default android_webview_junit_tests

# Run tests (any of these commands):
$ out/Default/bin/run_android_webview_junit_tests # All tests
$ out/Default/bin/run_android_webview_junit_tests -f *FindAddressTest#* # Same glob patterns work here

# Print both Java and C++ log messages to the console (optional) by passing "-v"
# to the test runner. Example:
$ out/Default/bin/run_android_webview_unittests -v # All tests, including logs
For junit tests, filter (-f) arguments require fully qualified class names (e.g. org.chromium.android_webview.robolectric.FindAddressTest), but replacing the package name with a glob wildcard (*), as in the example above, will work if the class name is unique.

Native unittests

These are any *_test.cc or *_unittest.cc test under //android_webview/. Currently, we only have tests under //android_webview/browser/ and //android_webview/lib/.

# Build
$ autoninja -C out/Default android_webview_unittests

# Run tests (any of these commands):
$ out/Default/bin/run_android_webview_unittests # All tests
$ out/Default/bin/run_android_webview_unittests -f AndroidStreamReaderURLRequestJobTest.* # Same glob patterns work here

# Print both Java and C++ log messages to the console (optional):
$ adb logcat

Layout tests and page cycler tests

WebView's layout tests and page cycler tests exercise the WebView installed on the system and instrument the system WebView shell app (system_webview_shell_apk). These test cases are defined in //android_webview/tools/system_webview_shell/.

Important: because these tests run against the WebView installed on the system, both these test targets automatically compile and install system_webview_apk and switch the WebView provider. This means you need to configure this target to be compatible with your system by following the full build instructions.

Note: we do not currently support running these tests on the emulator due to signing key mismatches with the preinstalled WebView shell (https://crbug.com/1205665 tracks supporting this).

# Build (this also compiles system_webview_shell_apk and system_webview_apk)
$ autoninja -C out/Default system_webview_shell_layout_test_apk

# Run layout tests (installs the test APK, WebView shell, and
# system_webview_apk, and also switches your WebView provider)
$ out/Default/bin/run_system_webview_shell_layout_test_apk

# Print both Java and C++ log messages to the console (optional):
$ adb logcat

To run page cycler tests instead, use the system_webview_shell_page_cycler_apk target and test runner in the steps above.

UI tests

Like layout and page cycler tests, WebView UI tests use the WebView installed on the system (and will automatically compile and install the system_webview_apk target). Unlike those tests however, this test suite does not depend on the system WebView shell app, so the setup is simpler. You will still need to follow the full build instructions to correctly configure the system_webview_apk target, but will not need to worry about compiling the WebView shell (and do not need to worry about https://crbug.com/1205665).

# Build (this also compiles system_webview_apk)
$ autoninja -C out/Default webview_ui_test_app_test_apk

# Run layout tests (installs the test APK and system_webview_apk and also
# switches your WebView provider)
$ out/Default/bin/run_webview_ui_test_app_test_apk

# Print both Java and C++ log messages to the console (optional):
$ adb logcat

Useful test runner options

Debugging flaky tests

$ out/Default/bin/run_webview_instrumentation_test_apk \ # Any test runner
    --num_retries=0 \ # Tests normally retry-on-failure; disable for easier repo
    --repeat=1000 \ # Repeat up to 1000 times for a failure
    --break-on-failure \ # Stop repeating once we see the first failure

Enable a Feature for a local run

$ out/Default/bin/run_webview_instrumentation_test_apk \ # Any test runner
    # Desired Features; see commandline-flags.md for more information
    --enable-features="MyFeature,MyOtherFeature" \

External tests

As WebView is an Android system component, we have some tests defined outside of the chromium repository, but which the team still maintains. For some of these tests, we have scripts to help chromium developers check these tests.

All of these tests are end-to-end, so they exercise whatever WebView implementation you've installed and selected on your device. This also means you can enable Features and commandline flags the same way as you would for production.


WebView has CTS tests, testing end-to-end behavior (using the WebView installed on the system). These tests live in the Android source tree (under //platform/cts/tests/tests/webkit/).

Chromium developers can download and run pre-built APKs for these test cases with:

# Install the desired WebView APK

# Run pre-built WebView CTS tests:
$ android_webview/tools/run_cts.py \
    --verbose \ # Optional
    -f=android.webkit.cts.WebViewTest#* # Supports similar test filters

# Print both Java and C++ log messages to the console (optional):
$ adb logcat
Tip: make sure your device locale is English (United States) per CTS setup requirements.

To disable failing CTS tests, please see the cts_config README file.

If you'd like to edit these tests, see internal documentation at http://go/clank-webview for working with Android checkouts.

AndroidX (Support Library)

WebView also has an AndroidX module, which has its own tests (similar to CTS tests). These tests live under the AOSP source tree, under //platform/frameworks/support/.

TODO(ntfschr): document the solution for http://crbug.com/891102, when that's fixed.