Jest: Test does not fail when promise throws and error is not caught, contrary to documentation.

[leonaves]

Do you want to request a feature or report a bug?
Report a bug.

What is the current behavior?
A promise that throws without being caught shows an unhandled promise rejection error in the console but the test passes.

If the current behavior is a bug, please provide the steps to reproduce and either a repl.it demo through https://repl.it/languages/jest or a minimal repository on GitHub that we can yarn install and yarn test.
https://github.com/leonaves/yarn-promise-bug/

What is the expected behavior?
As per https://facebook.github.io/jest/docs/tutorial-async.html#error-handling, the test should fail:

Note that if a Promise throws and the error is not handled, the test will fail.

Please provide your exact Jest configuration and mention your Jest, node, yarn/npm version and operating system.
Jest version 19.0.2, default configuration (see repo). Node v6.10.0 LTS. Yarn v0.21.3.

[leonaves]

I wouldn't know where to start submitting a PR for this, but if someone could point me in the right direction to get the ball rolling, I'd be happy to attempt to submit a fix for this myself.

[thymikee]

You must return that promise

[leonaves]

Embarrassing...

[chesleybrown]

So if you _forget_ to return the promise there is no way to have Jest fail because of the error thrown?

[SimenB]

We catch them during the test run now (and fail the test), but if it fails outside of a test run, we don't.

I wonder if we should stop uninstalling the handler at the end of tests. Or at least install a separate one between runs.

https://github.com/facebook/jest/blob/cf2b9e80a0b099c2f861660fd9cf589848106fa1/packages/jest-jasmine2/src/jasmine/Env.js#L247-L248