#prefer-equality-matcher

#Configuration

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

export default defineConfig([
  rstestPlugin.configs.recommended,
  {
    rules: {
      'rstest/prefer-equality-matcher': 'error',
    },
  },
]);

#Rule Details

Requires strict equality checks inside expect to use an equality matcher directly. expect(actual === expected).toBe(true) is harder to read and produces less useful failures than expect(actual).toBe(expected). The rule handles both === and !==, boolean expectations, an existing .not, and the resolves and rejects modifiers.

The rule recognizes toBe, toEqual, and toStrictEqual when they are the first called matcher in an assertion. It recognizes Rstest globals, imports and aliases, namespace access, import.meta.rstest, and the expect supplied by a test's TestContext. It also preserves assertion factories such as expect.soft, the second message argument of expect(actual, message), matcher argument trivia, and trailing commas.

Loose comparisons (== and !=), Chai property matchers, later matchers in a Chai chain, dynamic computed matcher names, locally shadowed names, and expect imported from another test framework are not reported. expect.poll(fn) and expect.element(locator) are only reported when the value passed to that factory is itself a strict equality comparison.

#Incorrect

test('matches the saved profile', () => {
  expect(savedProfile === expectedProfile).toBe(true);
  expect(savedStatus !== 'archived').not.toEqual(false);
});

#Correct

test('matches the saved profile', () => {
  expect(savedProfile).toBe(expectedProfile);
  expect(savedStatus).not.toEqual('archived');
});

#Suggestions

Each report offers three alternatives using toBe, toEqual, and toStrictEqual. The suggestion moves the left side of the comparison into expect, moves the right side into the matcher, and adjusts .not so the assertion keeps the same meaning. resolves or rejects, the written expect root, a second message argument, accessor quoting, surrounding trivia, and a trailing matcher-argument comma remain unchanged.

If comments or unusual accessor syntax inside an edited span cannot be preserved safely, the rule reports the assertion without suggestions.