README.md

jest-fail-on-console

Utility to make jest tests fail when console.error(), console.warn(), etc. are used

What problem is this solving?

Jest doesn't fail the tests when there is a console.error. In large codebase, we can end up with the test output overloaded by a lot of errors, warnings, etc.. To prevent this, we want to fail each test that is logging to the console. We also want to conserve a clear output of the original error.

This is what this utility is doing.

Install

yarn add -D jest-fail-on-console

or

npm install -D jest-fail-on-console

How to use

In a file used in the setupFilesAfterEnv option of Jest, add this code:

import failOnConsole from 'jest-fail-on-console'

failOnConsole()

// or with options:
failOnConsole({
  shouldFailOnWarn: false,
})

But I have some expected console errors/warning

If a console.error() is expected, then you should assert for it:

test('should log an error', () => {
  jest.spyOn(console, 'error').mockImplementation()
  // do your logic
  expect(console.error).toHaveBeenCalledWith('your error message')
})

Options

You can pass an object with options to the function:

errorMessage

Use this if you want to override the default error message of this library.

// signature
type errorMessage = (
  methodName: 'assert' | 'debug' | 'error' | 'info' | 'log' | 'warn',
  bold: (string: string) => string
) => string

shouldFailOnAssert

Use this to make a test fail when a console.assert() is logged.

• Type: boolean
• Default: false

shouldFailOnDebug

Use this to make a test fail when a console.debug() is logged.

• Type: boolean
• Default: false

shouldFailOnError

Use this to make a test fail when a console.error() is logged.

• Type: boolean
• Default: true

shouldFailOnInfo

Use this to make a test fail when a console.info() is logged.

• Type: boolean
• Default: false

shouldFailOnLog

Use this to make a test fail when a console.log() is logged.

• Type: boolean
• Default: false

shouldFailOnWarn

Use this to make a test fail when a console.warn() is logged.

• Type: boolean
• Default: true

silenceMessage

// signature
type silenceMessage = (
  message: string,
  methodName: 'assert' | 'debug' | 'error' | 'info' | 'log' | 'warn'
) => boolean

This function is called for every console method supported by this utility. If true is returned, the message will not show in the console and the test won't fail.

Example:

failOnConsole({
  silenceMessage: (errorMessage) => {
    if (/Not implemented: navigation/.test(errorMessage)) {
      return true
    }
    return false
  },
})

License

MIT

Maintainers

This project is maintained by Valentin Hervieu.

This project was originally part of @ricardo-ch organisation because I (Valentin) was working at Ricardo. After leaving this company, they gracefully accepted to transfer the project to me. ❤️

Credits

Most of the logic is taken from React's setupTests file.