#no-unneeded-async-expect-function

#Configuration

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

export default defineConfig([
  jestPlugin.configs.recommended,
  {
    rules: {
      'jest/no-unneeded-async-expect-function': 'error',
    },
  },
]);

#Rule Details

Disallow wrapping an expected promise in an unnecessary async function when using Jest promise assertions.

Jest promise assertions can receive the promise directly: await expect(doSomethingAsync()).rejects.toThrow() or await expect(doSomethingAsync()).resolves.toBe(value). Wrapping that call in async () => { await doSomethingAsync(); } is more verbose and makes the test harder to read without changing the assertion.

This rule reports expect() calls whose first argument is an async function with a single awaited call expression. It is fixable: the async wrapper is replaced with the awaited call. Renamed expect bindings imported from @jest/globals are also recognized.

Examples of incorrect code for this rule:

it('wrong1', async () => {
  await expect(async () => {
    await doSomethingAsync();
  }).rejects.toThrow();
});

it('wrong2', async () => {
  await expect(async function () {
    await doSomethingAsync();
  }).rejects.toThrow();
});

Examples of correct code for this rule:

it('right1', async () => {
  await expect(doSomethingAsync()).rejects.toThrow();
});

#Differences from ESLint

rslint also fixes equivalent concise arrow functions and parenthesized async function arguments, such as expect(async () => await doSomethingAsync()) and expect((async () => { await doSomethingAsync(); })). These shapes are handled as the same safe unwrap because tsgo preserves them explicitly in the AST.

rslint still reports the wrapper but does not fix it when the unwrapped call would not mean the same thing: when the awaited call contains another await of the wrapper's own, such as await run(await load()); when the wrapper has parameters, type parameters or a function-expression name; when a function expression wrapper reads this, arguments or new.target; when expect() has an explicit type argument; or when a comment inside the wrapper sits outside the awaited call and would be deleted.

#Original Documentation

• eslint-plugin-jest: no-unneeded-async-expect-function
• Source code