Running layout tests using the content shell

Basic usage

It is possible to run basic layout tests using the content shell. The advantage of content shell is that it will exercise the multi-processing code paths used by chromium.

To just dump the render tree, use the --dump-render-tree flag, as in:
out/Release/content_shell --dump-render-tree foo.html

Compiling

If you want to run layout tests build the target blink_tests - this includes all the other binaries required to run the tests.

Running

You can run layout tests using RWT.

run-webkit-tests storage/indexeddb

or execute the shell directly:

out/Debug/content_shell --remote-debugging-port=9222

This allows you see how your changes look in Chromium, and even connect with the devtools (by going to http://127.0.0.1:9222 from another window) to inspect your freshly compiled Blink. 

(Note: on the Mac, use "Content Shell", not "content_shell").

Debugging Renderers

To debug a renderer crash, ask Content Shell to wait for you to attach a debugger once it spawns a renderer process by adding the --renderer-startup-dialog flag:

out/Debug/content_shell --renderer-startup-dialog

Debugging workers and other subprocesses is simpler with --wait-for-debugger-children, which can have one of two values: "plugin" or "renderer".

Future Work

Reusing existing testing objects

To avoid writing (and maintaining!) yet another test controller, it is desirable to reuse an existing test controller. A possible solution would be to change DRT's test controller to not depend on DRT's implementation of the Blink objects, but rather on the Blink interfaces. In addition, we would need to extract an interface from the test shell object that can be implemented by content shell. This would allow for directly using DRT's test controller in content shell.
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