Yoga tries to be as close as possible to chrome in its flexbox behaviour. To ensure this most of Yoga's test suite is automatically generateded from running the corresponding layout in chrome using a webdriver which then generates C++ test which asserts that Yoga will produce matching outputs for that layout.

Running the Test Suite

  1. Yoga builds with buck. Follow their documentation to get up and running.
  2. For testing Yoga relies on gtest as a submodule. After cloning Yoga run git submodule init followed by git submodule update.
  3. In a terminal from the root of your Yoga checkout run buck test //:yoga.

Adding a Test

Instead of manually writing a test which ensures parity with web implementations of Flexbox we make use of a generated test suite. We use gentest/gentest.rb to generate this test suite. Write the html which you want to verify in Yoga and put it in the gentest/fixtures folder, such as the following.

<div id="my_test" style="width: 100px; height: 100px; align-items: center;">
  <div style="width: 50px; height: 50px;"></div>

Run gentest/gentest.rb to generate test code and re-run buck test //:yoga to validate the behavior. One test case will be generated for every root div in the input html with the string in the id corresponding to the test name.

You should run bundle install in the gentest directory to install dependencies for the gentest/gentest.rb Ruby script.

Manual test

For some aspects of Yoga we cannot generate a test using the test generation infrastructure described earlier. For these cases we manually write a test in the /tests directory.