noExportsInTest (JavaScript)

Language JavaScript (and super languages)

Summary

Rule available since: v1.6.0
Diagnostic Category: lint/suspicious/noExportsInTest
This rule is recommended, meaning it is enabled by default.
This rule doesn’t have a fix.
The default severity of this rule is error.
This rule belongs to the following domains:
- test
Sources:
- Inspired from jest/no-export

How to configure

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{
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  "linter": {
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    "rules": {
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      "suspicious": {
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        "noExportsInTest": "error"
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      }
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    }
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  }
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}

Description

Disallow using export or module.exports in files containing tests

This rule aims to eliminate duplicate runs of tests by exporting things from test files. If you import from a test file, then all the tests in that file will be run in each imported instance, so bottom line, don’t export from a test, but instead move helper functions into a separate file when they need to be shared across tests.

Examples

Invalid

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export function myHelper() {}
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describe('a test', () => {
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    expect(1).toBe(1);
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});

code-block.js:1:1 lint/suspicious/noExportsInTest ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Do not export from a test file.
  
  > 1 │ export function myHelper() {}
      │ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    2 │ describe('a test', () => {
    3 │     expect(1).toBe(1);
  
  ℹ Importing a test file runs all of its tests again in the importing file. This causes duplicate test runs.
  
  ℹ Move the exported code into a separate file and import it from the tests that need it.

Valid

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function myHelper() {}
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describe('a test', () => {
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    expect(1).toBe(1);
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});