prefer-output-null.md

Disallow invalid RuleTester test cases with the output the same as the code. (prefer-output-null)

⚒️ The --fix option on the command line can automatically fix some of the problems reported by this rule.

Instead of repeating the test case code, using output: null is more concise and makes it easier to distinguish whether a test case provides an autofix.

Rule Details

The rule reports an error if it encounters a test case where the output is the same as the code.

Examples of incorrect code for this rule:

/* eslint eslint-plugin/prefer-output-null: error */

new RuleTester().run('foo', bar, {
  valid: [],
  invalid: [
    { code: 'foo', output: 'foo', errors: [{ message: 'bar' }] },
  ],
});

Examples of correct code for this rule:

/* eslint eslint-plugin/prefer-output-null: error */

new RuleTester().run('foo', bar, {
  valid: [],
  invalid: [
    { code: 'foo', output: null, errors: [{ message: 'bar' }] },
  ],
});