Hacking on Sky

Building

  • Follow the setup & build instructions for Mojo

Running applications

  • ./sky/tools/skydb start out/Debug [url]

    skydb has numerous commands, visible via skydb help. Common ones include:

    • skybd start BUILD_DIR [url]
    • skydb load [url]
    • skydb stop
    • skydb start_tracing # Starts recoding a performance trace (use stop_tracing to stop)
    • skydb print_crash # Symbolicate the most recent crash from android.

Once skydb start is issued, all subsequent commands will be sent to the running mojo_shell instance (even on an attached android device). skydb start reads gn args from the passed build directory to determine whether its using android, for example.

  • ./sky/tools/test_sky --debug
    • This runs the tests against //out/Debug. If you want to run against //out/Release, omit the --debug flag.

Running tests manually

  • out/downloads/sky_server -t Debug . 8000 (If you don't have sky_server yet, run sky/tools/download_sky_server.)
  • out/Debug/mojo_shell --args-for="mojo:native_viewport_service --use-headless-config --use-osmesa" --args-for"=mojo:sky_viewer --testing" --content-handlers=text/sky,mojo:sky_viewer --url-mappings=mojo:window_manager=mojo:sky_tester,mojo:surfaces_service=mojo:fake_surfaces_service mojo:window_manager
  • The sky_tester should print #READY when ready
  • Type the URL you wish to run, for example http://127.0.0.1:8000/sky/tests/lowlevel/text.html, and press the enter key
  • The harness should print the results of the test. You can then type another URL.

Writing tests

  • We recommend using the unittest.dart testing framework.
  • See sky/tests/lowlevel/attribute-collection.sky for an example.

Adding pixel tests

Sky does not have proper pixel tests. Instead we have only reftests. If you want a pixel test, you need to dump the png from a reftest, upload it to googlestorage and then put and pointing to the uploaded file in the reference.

  1. Create your test (e.g. foo.sky).
  2. Create an dummy reference file (foo-expected.sky).
  3. Run the test (it will fail).
  4. Copy the -actual.png file to googlestorage (see below).
  5. Put an <img> pointing to your newly uploaded png in the reference file at http://storage.googleapis.com/mojo/sky-pngs/SHA1_HASH_HERE

Copying the file to googlestorage:

$ sha1sum ../out/Debug/layout-test-results/framework/flights-app-pixels-actual.png
db0508cdfe69e996a93464050dc383f6480f1283  ../out/Debug/layout-test-results/framework/flights-app-pixels-actual.png
$ gsutil.py cp ../out/Debug/layout-test-results/framework/flights-app-pixels-actual.png gs://mojo/sky-pngs/db0508cdfe69e996a93464050dc383f6480f1283

Long-term, we should not have these tests at all and should just dump paint commands. In the short-term, if we find we're doing this a lot we should obviously automate this process, e.g. test_sky could do all of this work, including spitting out the correct reference file.