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, instrumenting the WebView shell (system_webview_shell_apk, org.chromium.webview_shell). These test cases are defined in //android_webview/tools/system_webview_shell/.

# Build
$ autoninja -C out/Default system_webview_shell_layout_test_apk

# Install the desired WebView APK

# Run layout tests (installs WebView shell):
$ 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.

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.