Testing and debugging Cronet for Android

Checkout and build

See instructions in the common checkout and build.

Running tests locally

First, connect an Android device by following the Plug in your Android device steps. Prefer using a device running a userdebug build.

Alternatively, you can pass the --x86 flag to gn to test on a local emulator -- make sure you substitute out/Debug for out/Debug-x86 in the instructions below.

Running Cronet Java unit tests

To run Java unit tests that actuate the Cronet API:

$ ./components/cronet/tools/cr_cronet.py gn
$ ./components/cronet/tools/cr_cronet.py build-test

To run particular tests specify the test class and method name to the build-test command. For example:

$ ./components/cronet/tools/cr_cronet.py build-test -f QuicTest#testQuicLoadUrl

Running net_unittests and cronet_unittests_android

To run C++ and Java unit tests of net/ functionality:

$ ./components/cronet/tools/cr_cronet.py gn
$ ninja -C out/Debug net_unittests
$ ./out/Debug/bin/run_net_unittests --fast-local-dev

For more information about running net_unittests, read Android Test Instructions.

There are a small number of C++ Cronet unit tests, called cronet_unittests_android, that can be run by following the above instructions and substituting cronet_unittests_android for net_unittests.

Running Cronet performance tests

To run Cronet's perf tests, follow the instructions in components/cronet/android/test/javaperftests/run.py

Running tests remotely

Once you've uploaded a Chromium change list using git cl upload, you can launch a bot to build and test your change list:

$ git cl try -b android_cronet_tester

This will run both the Cronet Java unit tests and net_unittests.


Debug Log

Messages from native (C++) code appear in the Android system log accessible with adb logcat. By default you will see only messages designated as FATAL. To enable more verbosity:

See VLOG(1) and VLOG(2) logging:

$ adb shell setprop log.tag.CronetUrlRequestContext VERBOSE

See VLOG(1) logging:

$ adb shell setprop log.tag.CronetUrlRequestContext DEBUG

See NO (only FATAL) logging:

$ adb shell setprop log.tag.CronetUrlRequestContext NONE

Network Log

NetLog is Chromium's network logging system. To create a NetLog dump, you can use the following pair of methods:


Unlike the Android system log which is line-based, the Chromium log is formatted in JSON. As such, it will probably not be well-formed until you have called the stopNetLog() method, as filesystem buffers will not have been flushed.

Retrieve the file from your device's file system, and import it to chrome browser at chrome://net-internals/#import, or http://catapult-project.github.io/catapult/netlog_viewer which helps to visualize the data.

Symbolicating crash stacks

If an app or test using Cronet crashes it can be useful to know the functions and line numbers involved in the stack trace. This can be done using the Android system log:

$ ./components/cronet/tools/cr_cronet.py stack

Or using tombstones left behind after crashes:

$ CHROMIUM_OUTPUT_DIR=out/Debug ./build/android/tombstones.py