jest-plugin-unhandled-promise

Surfaces unhandled promise rejections in jest tests.

NOTE: This is unecessary in Jest 21+

Jest 21 introduced unhandled promise handling natively within the framework. Therefore, this plugin is unnecessary.

Getting Started

Install jest-plugin-unhandled-promise using yarn:

yarn add --dev jest-plugin-unhandled-promise

Motivation

Currently, when running tests in jest, if you have an unhandled promise rejection, you'll see this warning:

(node:23112) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: unhandled error
(node:23112) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

Your tests may or may not pass, and you might miss this error.

With jest-plugin-unhandled-promise, you'll see this nice, red stack trace in your console:

Error: unhandled error
  at /Users/mark/projects/negativetwelve/jest-plugin-unhandled-promise/src/__tests__/install.spec.js:9:61
  at Promise (<anonymous>)
  at /Users/mark/projects/negativetwelve/jest-plugin-unhandled-promise/src/__tests__/install.spec.js:9:7
  at Promise (<anonymous>)
  at /Users/mark/projects/negativetwelve/jest-plugin-unhandled-promise/src/__tests__/install.spec.js:7:56
  at _callee4$ (/Users/mark/projects/negativetwelve/jest-plugin-unhandled-promise/src/__tests__/install.spec.js:59:17)
  at tryCatch (/Users/mark/projects/negativetwelve/jest-plugin-unhandled-promise/node_modules/regenerator-runtime/runtime.js:65:40)
  at Generator.invoke [as _invoke] (/Users/mark/projects/negativetwelve/jest-plugin-unhandled-promise/node_modules/regenerator-runtime/runtime.js:303:22)
  at Generator.prototype.(anonymous function) [as next] (/Users/mark/projects/negativetwelve/jest-plugin-unhandled-promise/node_modules/regenerator-runtime/runtime.js:117:21)
  at step (/Users/mark/projects/negativetwelve/jest-plugin-unhandled-promise/src/__tests__/install.spec.js:2:364)

Now you can easily handle errors and fix up your specs!

Usage

If you want, you can import installUnhandledPromise from jest-plugin-unhandled-promise at the top of every test:

import installUnhandledPromise from 'jest-plugin-unhandled-promise';

// Pass in your custom log function.
installUnhandledPromise(console.log);

If you want to install it as a global for all tests, you can modify the jest section of your package.json to include:

"jest": {
  "setupFiles": [
    "jest-plugin-unhandled-promise/setup"
  ]
}

Contributing

If you have any ideas on how this module could be better, create an Issue or submit a PR.