Blog / FoundryVTT Module Test Automation

FoundryVTT Module Test Automation

I really loath manual testing. In a pro­fes­sion­al setting, nearly all of my projects are developed using TDD (test driven de­vel­op­ment). However, a bit to my em­barass­ment, most of my personal projects haven't received this level of care. In this article, I'm going to overview how I bucked that trend by in­tro­duc­ing testing to a friend's project.

Back in 2017, I started GM'ing the FFG Star Wars Tabletop RPG for my friends. Over the years, folks moved and eventually the game migrated online. In early 2021, a friend suggested I explore FoundryVTT. It quickly became our favorite tabletop RPG platform due to its ex­ten­si­bil­i­ty.

We used the Star Wars FFG System, and shortly thereafter, my friend began de­vel­op­ment of an add-on module (FFG Star Wars En­hance­ments) with features not really suited for the core system.

Since then, FoundryVTT has undergone three major releases. While I've con­tributed a number of features to the module, the majority of the main­te­nance and testing during those releases has fallen on my friend's shoulders. After discussing options, I decided to use my background in CI/CD workflow de­vel­op­ment to setup automated testing.


In many projects, a good mocking framework will give you sufficient coverage for testing against in­te­gra­tion points with other libraries. In our case, FoundryVTT ef­fec­tive­ly acts as a framework for the module. This tightly couples the project's code with the im­ple­men­ta­tion of the FoundryVTT API. The level of mocking that would be required to adequetly test a feature would prove extremely unreliable during a major version change. Many frameworks eventually create a testing scaffold that blends production code and fakes. This may be in FoundryVT­T's future, but at time of writing it does not exist yet.

That leaves the next best option being in­te­gra­tion and end-to-end tests. The difference between them is subtle. For the purposes of this article, in­te­gra­tion tests attempt to minimize their reliance on UI in­ter­ac­tions and end-to-end tests attempt to primarily test the UI.

Ad­di­tion­al­ly, FoundryVTT (reasonably) restricts dis­tri­b­u­tion of their software. That makes automating tests chal­leng­ing, par­tic­u­lar­ly in CI.


Quench is a FoundryVTT module that can be used to run tests from your module within FoundryVTT. This allows you to write Mocha tests and run them within FoundryVTT. We use Quench for our in­te­gra­tion tests, where we try to avoid UI in­ter­ac­tions.

Excerpt from a quench test:

it(`creates a new ${option} journal`, async () => {
    // Hook to capture when our dialog has actually rendered
    const rendered = $.Deferred();
    Hooks.once("renderApplication", (...args) => rendered.resolve(args));

    const dialog = await create_datapad_journal();

    const [application, $html] = await rendered.promise();

    // Sanity check the renderApplication hook returned our dialog

    ... 8< snip ...

    const datapad = game.journal.getName(option);

    const page = datapad.pages?.values()?.next().value;


To see how we use Quench in action, check out our Quench tests.


For full end-to-end tests, we've opted for Cypress. Cypress is a good fit for our project, because our tests really are purely frontend tests. Cypress's opin­ion­at­ed approach to testing encourages us to write tests in a way that avoids a lot of the patterns that make UI tests brittle.

We developed a number of Cypress Commands that handle installing systems, modules, and creating a test world.

Excerpt from a cypress test:

// Open the crawl dialog

// Create a folder for the Opening Crawl journals
cy.get(".window-content .yes").click();

// Create a crawl
cy.get("#ffg-star-wars-enhancements-opening-crawl-select .create").click();

Aside: If you end-up exploring Cypress, I strongly recommend reading their doc­u­men­ta­tion. Specif­i­cal­ly, Con­di­tion­al Testing. Wrapping your head around the "Element existence" section will go a long way to avoiding common pitfalls.

Tests inside your tests?

An astute reader might have noticed that Quench requires a running instance of FoundryVTT to execute tests. To support running Quench tests in CI, we actually execute the Quench tests via Cypress.

Honestly, this feels a bit hack. But, writing in­te­gra­tion tests in Quench feels more fluid, and this gives us a bit of the best of both worlds.

Docker Compose

Having the ability to quickly spin up and tear down different versions of FoundryVTT is extremely useful when testing. Locally, I'm using Docker Compose with felddy/foundryvtt-docker's docker container.

The container is really well designed and pretty flexible. To learn more about our Docker Compose con­fig­u­ra­tion and usage, check out our Cypress README.md.

GitHub Actions

Tests that don't run as part of CI inevitably end up broken.

Aside: I actually worked backwards from this re­quire­ment to design all of the above, but explaining it in that order would have been very difficult.

Cypress makes testing in GitHub very each. They expose a github-action for running Cypress tests that handle launch and readiness checks for your server. Ad­di­tion­al­ly, it au­to­mat­i­cal­ly archives video recordings of your test runs.

To run FoundryVTT in a GitHub action, we reuse the learnings from Docker Compose. The GitHub Ubuntu runners come preloaded with Docker. It's easy enough to craft a docker run command that will launch FoundryVTT with our module's code installed.

From there, a few challenges remained:

  1. Caching the in­stal­la­tion to avoid abusive downloads of FoundryVTT
  2. Securing FoundryVTT cre­den­tials while still supporting tests on user forks
  3. Requiring approval only on PRs from forks
  4. Race conditions!

Excerpt from our GitHub action con­fig­u­ra­tion. See Star­WarsF­FG-En­hance­ments repository for all workflows.

- if: ${{ steps.container_cache.outputs.cache-hit != 'true' }}
  name: Launch FoundryVTT and run Cypress Tests
  uses: cypress-io/github-action@v5
      start: >-
          sudo docker run
          --name foundryvtt
          --env FOUNDRY_ADMIN_KEY=test-admin-key
          --env FOUNDRY_USERNAME=${{ secrets.FOUNDRY_USERNAME }}
          --env FOUNDRY_PASSWORD=${{ secrets.FOUNDRY_PASSWORD }}
          --env FOUNDRY_LICENSE_KEY=${{ secrets.FOUNDRY_LICENSE_KEY }}
          --publish 30001:30000/tcp
          --volume ${{ github.workspace }}/data:/data
      wait-on: "http://localhost:30001"
      wait-on-timeout: 120

More detail about the repository con­fig­u­ra­tion can be found in the Cypress README.md.

1. Caching

To ensure we don't repet­i­tive­ly download the FoundryVTT ap­pli­ca­tion, we need to setup caching within the GitHub workflow. For­tu­nate­ly, the felddy/foundryvtt docker image supports this natively. All we need to do is cache the data/container_cache directory. Un­for­tu­nate­ly, the container entrypoint will still au­then­ti­cate to the FoundryVTT API if a username/password is provided. Normally, this feature gives you a way to make sure you're running the latest release. In our case, we don't want that. To avoid it, we have two "steps": one if the cache hits and one if the cache misses. We omit the FOUNDRY_USERNAME and FOUNDRY_PASSWORD when we have a cache hit, skipping the check entirely.

To actually cache, we use the actions/cache@v3 action provided by GitHub. The only special thing we do here is an additional step that saves on failure to ensure we capture the in­stal­la­tion regardless of whether the tests pass. The cache should hang around for at least seven days.

2. Security cre­den­tials

Getting the level of flex­i­bil­i­ty we wanted out of GitHub proved a little difficult. We wanted to know that tests would pass before merging a pull request. To support con­trib­u­tors forking our repository, that means checking out their code and running tests against it. However, these tests launch a docker container that requires secrets (FOUNDRY_USERNAME, FOUNDRY_PASSWORD, and FOUNDRY_LICENSE_KEY). To make those secrets accessible in workflows run with code from forks, we use the pull_request_target event.

This is po­ten­tial­ly very risky. To limit our exposure, we use a GitHub "en­vi­ron­men­t" on PRs orig­i­nat­ing from forks called requires-approval. The en­vi­ron­ment has a few con­trib­u­tors assigned to it that must manually approve every run.

3. Approval only on forks

Requiring approval only for PRs coming from forks was tricky to configure. The yaml SDL provided by GitHub actions is pretty flexible, but code reuse can get difficult. There isn't a good way to specify the workflow en­vi­ron­ment based on the origin. To work around that limitation, we create two jobs: one for upstream and one for forks. That splits the workflow across cypress.yaml where the jobs are defined and cypress-impl.yaml where the actual steps are defined.

This was a bit quirky to setup, but the sharp edges are pretty well documented in the configs.

4. Race conditions!

The free GitHub Actions runners are awesome! But they definitely run in a low per­for­mance en­vi­ron­ment. The heavy load will un­for­tu­nate­ly/for­tu­nate­ly highlight every sloppy race condition in your tests. Adding fixed length timeouts generally is not reliable.

This makes tests trickier to write. You have to be very careful to be sure you've waited for the right thing before proceeding.

Ad­di­tion­al­ly, some of our code, the system code, and FoundryVTT itself is not written in a way that makes it easy to know when you can proceed.

A few examples:

  • The close button on "Ap­pli­ca­tion­s" have a 500ms timer before it attaches the onClick handler to prevent ac­ci­den­tal­ly closing. Meaning, clicking it does nothing from fast automation.
  • FoundryVTT has Hooks for a lot of asyn­chro­nous events, but reasonably not everything. If you launch a dialog, you need to be thoughtful about how to know the dialog resolved. This could be done with a custom Hook, or by looking for a side-effect (like the creation of a Journal).


I hope that this proves useful to someone who hopes to setup test automation for a FoundryVTT module.

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