#require-to-throw-message

#Configuration

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

export default defineConfig([
  rstestPlugin.configs.recommended,
  {
    rules: {
      'rstest/require-to-throw-message': 'error',
    },
  },
]);

#Rule Details

Requires toThrow() and its toThrowError() alias to specify the expected error. Without an argument, either matcher passes for any thrown error, so a test can continue passing after the code starts throwing for an unrelated reason. The argument may be a string, template literal, regular expression, error constructor, or any other expression accepted by Rstest's expect API.

The rule checks the first called matcher in a call-style assertion chain, including expect.soft(...) and promise modifiers such as rejects. Negated forms such as not.toThrow() are exempt because they assert that no error is thrown. Chai-style throw and throws assertions are not checked. Although Rstest does not expose throw matchers on expect.poll(...) or expect.element(...), the same syntax-only check applies if either form is written.

Every Rstest expect source is recognized: globals, named and renamed imports, require destructuring, namespace imports, whole-module require, import.meta.rstest, Playwright integrations, and the expect supplied by a test's TestContext. The rule does not need type information to recognize any of them. An expect imported from another assertion library or shadowed by a local value is ignored.

#Incorrect

test('rejects an invalid account', async () => {
  expect(() => loadAccount('missing')).toThrow();
  await expect(loadAccount('missing')).rejects.toThrowError();
});

#Correct

test('rejects an invalid account', async () => {
  expect(() => loadAccount('missing')).toThrow('Account not found');
  await expect(loadAccount('missing')).rejects.toThrowError(/not found/);
});