#Rslint

Rslint is an ESLint-compatible linter for JavaScript and TypeScript. Its built-in rstestPlugin adds rules for common mistakes in Rstest test definitions, assertions, mocks, and snapshots.

Install @rslint/core in your project, then enable the recommended preset in rslint.config.ts:

npm add @rslint/core -D

yarn add @rslint/core -D

pnpm add @rslint/core -D

bun add @rslint/core -D

deno add npm:@rslint/core -D

#Dedicated test files

If your tests use filenames such as *.test.ts or *.spec.ts, scope the preset to the same file pattern that Rstest discovers by default:

import { defineConfig, rstestPlugin } from '@rslint/core';

export default defineConfig([
  {
    ...rstestPlugin.configs.recommended,
    files: [
      '**/*.{test,spec}.{js,jsx,ts,tsx,cjs,cjsx,cts,ctsx,mjs,mjsx,mts,mtsx}',
    ],
  },
]);

This pattern covers JavaScript and TypeScript files with .js, .jsx, .ts, .tsx, .cjs, .cjsx, .cts, .ctsx, .mjs, .mjsx, .mts, and .mtsx extensions. The recommended preset does not declare a files pattern, so adding one keeps Rstest-specific rules focused on test files and leaves production files to your other Rslint configuration items.

#In-source tests

With in-source testing, tests live alongside production code and use import.meta.rstest. Apply the preset to every linted file so it can check both in-source tests and dedicated test files:

import { defineConfig, rstestPlugin } from '@rslint/core';

export default defineConfig([rstestPlugin.configs.recommended]);

No additional Rslint globals are required for import.meta.rstest.

#Run Rslint

Run Rslint from your project root:

npm exec rslint

yarn exec rslint

pnpm exec rslint

bun exec rslint

deno exec npm:rslint

A successful run prints a summary similar to this:

start   Linting...
success Lint passed in 92ms (1 file, 14 rules, 14 threads)

When Rslint finds a problem, it reports the rule name, source location, code frame, and failure summary:

start   Linting...

  rstest/no-identical-title  — [error] Test title is used multiple times in the same describe block
  ╭─┴──────────( invalid.test.ts:8:8 )─────
  │ 7 │
  │ 8 │  test('same title', () => {
  │ 9 │    expect(false).toBeFalsy();
  ╰────────────────────────────────

error   Lint failed with 1 error in 31ms (1 file, 14 rules, 14 threads)

You can also add the command to the scripts section of package.json and run it through your package manager's lint script.

#Explore the rules

The Rslint rstestPlugin preset documents the available configuration and usage patterns. To see which rules are included in the recommended preset, open the Rstest rules list.