common-pitfalls.md

Common Pitfalls

AVA in Docker

If you run AVA in Docker as part of your CI, you need to fix the appropriate environment variables. Specifically, adding -e CI=true in the docker exec command. See https://github.com/avajs/ava/issues/751.

AVA uses is-ci to decide if it's in a CI environment or not using these variables.

AVA and connected client limits

You may be using a service that only allows a limited number of concurrent connections. For example, many database-as-a-service businesses offer a free plan with a limit on how many clients can be using it at the same time. AVA can hit those limits as it runs multiple processes, but well-written services should emit an error or throttle in those cases. If the one you're using doesn't, the tests will hang.

Use the concurrency flag to limit the number of processes ran. For example, if your service plan allows 5 clients, you should run AVA with concurrency=5 or less.

Async operations

You may be running an async operation inside a test and wondering why it's not finishing. If your async operation uses promises, you should return the promise:

test(t => {
  return fetch().then(data => {
    t.is(data, 'foo');
  });
});

If it uses callbacks, use test.cb:

test.cb(t => {
  fetch((err, data) => {
    t.is(data, 'bar');
    t.end();
  });
});

Alternatively, promisify the callback function using something like pify.

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