js/ui/environment.js: Split out initial UI setup (Tweener initialization,
  ClutterContainer monkey-patching) into a separate file we can import from tests.

tests/: Directory for various types of tests
tests/run-test.sh: Shell script that to run tests with an appropriate
  environment set up.

tests/testcommon/: Common modules and data for tests
tests/interactive/: Interactive tests

tests/interactive/box-layout.js: A sample test of StLayout

https://bugzilla.gnome.org/show_bug.cgi?id=595987