The playground

The playground is the quickest way to hack on the internals of Theatre. It also hosts our end-to-end tests. It uses a build setup (see the live-reload esbuild server in ./devEnv/build.ts) that builds all the related packages in one go, so you don't have to run a bunch of build commands separately to start developing.

Directory structure

src/
  shared/                      <---- playgrounds shared with teammates.
    [playground-name]/         <---- each playground has a name...
      index.tsx                <---- and an entry file.

  personal/                    <---- personal playgrounds (gitignored).
    [playground-name]/         <---- personal playgrounds also have names,
      index.tsx                <---- and an entry file.

  tests/                       <---- playgrounds for e2e testing.
    [playground-name]/         <---- the name of the test playground,
      index.tsx                <---- and its entry file.
      [test-file-name].e2e.ts  <---- The playwright test script that tests this particular playground.
      [test2].e2e.ts           <---- We can have more than one test file per playground.

How to use the playground

Simply run yarn run serve in this folder to start the dev server.

There are some shared playgrounds in src/shared which are committed to the repo. You can make your own playgrounds in src/personal which will be .gitignored. Note that every playground must include an entry file called index.tsx (as you see in the Directory structure section).

How to write and run end-to-end tests

The end-to-end tests are in the src/tests folder. Look at directory structure to see how test files are organized.

The end-to-end tests are made using playwright. You should refer to playwright's documentation

$ cd playground
$ yarn test # runs the end-to-end tests
$ yarn test --project=firefox # only run the tests in firefox
$ yarn test --project=firefox --headed # run the test in headed mode in firefox
$ yarn test --debug # run in debug mode using the inspector: https://playwright.dev/docs/inspector

Using playwright codegen

To use playwright's codegen tool, first serve the playground and then run the codegen on the a url that points to the playground you wish to test:

$ cd playground
$ yarn serve # first serve the playground
$ yarn playwright codegen http://localhost:8080/tests/[playground-name] # run the codegen for [playground-name]

Visual regression testing

Some .e2e.ts files also contain visual regression tetst. These tests run only the the CI using Github actions. Look at the example at src/tests/setting-static-props/test.e2e.ts for an example of recording and diffing a screenshot.

Note that CI runs the visual regression tests in a linux VM, which is bound to produce a slightly different screenshot than a browser on Mac/Windows. Because of that, we have a docker-compose.yml file at the root of the repo which you can use to produce a screenshot in a linux vm. Here is how you can use it:

$ cd repo
$ docker-compose up -d # start the linux vm
$ docker-compose exec -it node bash # ssh into the vm
$ yarn
$ yarn test:e2e:ci

If you're submitting a PR that breaks the visual regression tests and you're not familiar with Docker, simply ask the mainainers to update the screenshots for you.

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