Import Integrity

Appearance

import-integrity/no-test-imports-in-prod ​

Ensures that production code does not import test code.

Rule Details ​

This rule flags two kinds of imports in production code:

  • Imports of test files (e.g. b.test.ts or anything inside __test__/)
  • Imports of symbols prefixed with _testOnly (test helpers that live in production files but are intended only for test consumption)

Both are usually mistakes, and both contribute to bundle size bloat when test frameworks and helpers leak into production builds.

A file is considered a test file based on filename and folder conventions (e.g. .test., .spec, __test__). The full list of patterns, and how to add your own, is on the testFilePatterns page.

The _testOnly prefix is the corresponding mechanism for test helpers that need to live alongside production code. This rule enforces the constraint from the production side; the no-test-only-imports rule enforces the matching constraint from the test side, ensuring _testOnly-prefixed symbols are only imported by tests.

Examples ​

Incorrect ​

js
/*
.
├── a.ts
└── __test__/
    └── b.ts
*/

// a.ts
import { b } from './__test__/b';

// __test__/b.ts
export const b = 10;
js
/*
.
└── a.ts
*/

// a.ts
import { _testOnlyHelper } from './helpers';

Correct ​

js
/*
.
├── a.ts
├── helpers.ts
└── __test__/
    └── a.test.ts
*/

// a.ts
import { helper } from './helpers';
export const a = helper(10);

// __test__/a.test.ts
import { a } from '../a';

Test files importing production files is fine. Only the reverse is flagged.

Configuration ​

Options ​

This rule has no options. To configure which files count as test files, set testFilePatterns at the package level.

When not to use this rule ​

We don't recommend disabling this rule. If you have a legitimate need to import a test helper from production code, the helper probably doesn't belong in production code at all. Move it to a test file, or restructure the code so the production version doesn't depend on test infrastructure.