Instructions on how to verify your changes

Testing

• To test a file, you can run npm run test -- <FILEPATH> where FILEPATH is a path to a *.test.ts file, relative to the working directory.
• Test files are usually defined alongside their implementation. So if you are working on front_end/panels/timeline/TimelinePanel.ts, you would expect the test file to be defined in front_end/panels/timeline/TimelinePanel.test.ts.
• You can also test an entire directory. For example, npm run test -- front_end/models/trace will run all tests in that directory.

Building & compiling

• Check for build issues by running autoninja -C out/Default.

Linting

• npm run lint will execute ESLint and StyleLint. It will report any violations and automatically fix them where possible.
• To run the linter on a specific file or directory, you can run npm run lint -- <PATH> where PATH is a path to a file or directory. This will also automatically fix violations where possible.

Best practices

• Run tests often to verify your changes.
• Prefer using a fast build, if it exists, to keep the feedback loop shorter.
• Periodically build to check for errors.
• Run git cl presubmit -u at the end of your code changes.