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feat(rule): disallow unnecessary async function wrapper for single await call
Signed-off-by: hainenber <[email protected]>
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‎README.md‎

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‎docs/rules/no-async-wrapper-for-expected-promise.md‎

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# Disallow unnecessary async wrapper for expected promises (`no-async-wrapper-for-expected-promise`)
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💼 This rule is enabled in the ✅ `recommended`
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[config](https://github.com/jest-community/eslint-plugin-jest/blob/main/README.md#shareable-configurations).
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🔧 This rule is automatically fixable by the
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[`--fix` CLI option](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix).
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<!-- end auto-generated rule header -->
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`Jest` can handle fulfilled/rejected promisified function call normally but
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occassionally, engineers wrap said function in another `async` function that is
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excessively verbose and make the tests harder to read.
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## Rule details
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This rule triggers a warning if a single `await` function call is wrapped by an
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unnecessary `async` function.
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Examples of **incorrect** code for this rule
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```js
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it('wrong1', async () => {
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await expect(async () => {
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await doSomethingAsync();
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}).rejects.toThrow();
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});
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it('wrong2', async () => {
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await expect(async function () {
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await doSomethingAsync();
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}).rejects.toThrow();
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});
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```
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Examples of **correct** code for this rule
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```js
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it('right1', async () => {
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await expect(doSomethingAsync()).rejects.toThrow();
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});
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```

‎src/__tests__/__snapshots__/rules.test.ts.snap‎

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@@ -15,6 +15,7 @@ exports[`rules should export configs that refer to actual rules 1`] = `
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"jest/max-expects": "error",
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"jest/max-nested-describe": "error",
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"jest/no-alias-methods": "error",
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"jest/no-async-wrapper-for-expected-promise": "error",
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"jest/no-commented-out-tests": "error",
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"jest/no-conditional-expect": "error",
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"jest/no-conditional-in-test": "error",
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"jest/max-expects": "error",
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"jest/max-nested-describe": "error",
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"jest/no-alias-methods": "error",
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"jest/no-async-wrapper-for-expected-promise": "error",
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"jest/no-commented-out-tests": "error",
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"jest/no-conditional-expect": "error",
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"jest/no-conditional-in-test": "error",
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"rules": {
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"jest/expect-expect": "warn",
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"jest/no-alias-methods": "error",
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"jest/no-async-wrapper-for-expected-promise": "error",
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"jest/no-commented-out-tests": "warn",
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"jest/no-conditional-expect": "error",
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"jest/no-deprecated-functions": "error",
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"rules": {
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"jest/expect-expect": "warn",
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"jest/no-alias-methods": "error",
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"jest/no-async-wrapper-for-expected-promise": "error",
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"jest/no-commented-out-tests": "warn",
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"jest/no-conditional-expect": "error",
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"jest/no-deprecated-functions": "error",

‎src/__tests__/rules.test.ts‎

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@@ -2,7 +2,7 @@ import { existsSync } from 'fs';
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import { resolve } from 'path';
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import plugin from '../';
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5-
const numberOfRules = 64;
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const numberOfRules = 65;
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const ruleNames = Object.keys(plugin.rules);
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const deprecatedRules = Object.entries(plugin.rules)
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.filter(([, rule]) => rule.meta.deprecated)

‎src/index.ts‎

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const recommendedRules = {
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'jest/expect-expect': 'warn',
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'jest/no-alias-methods': 'error',
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'jest/no-async-wrapper-for-expected-promise': 'error',
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'jest/no-commented-out-tests': 'warn',
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'jest/no-conditional-expect': 'error',
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'jest/no-deprecated-functions': 'error',

‎src/rules/__tests__/no-async-wrapper-for-expected-promise.test.ts‎

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import dedent from 'dedent';
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import rule from '../no-async-wrapper-for-expected-promise';
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import { FlatCompatRuleTester as RuleTester, espreeParser } from './test-utils';
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const ruleTester = new RuleTester({
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parser: espreeParser,
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parserOptions: {
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ecmaVersion: 2017,
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},
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});
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ruleTester.run('no-async-wrapper-for-expected-promise', rule, {
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valid: [
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'expect.hasAssertions()',
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dedent`
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it('pass', async () => {
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expect();
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})
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`,
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dedent`
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it('pass', async () => {
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await expect(doSomethingAsync()).rejects.toThrow();
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})
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`,
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dedent`
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it('pass', async () => {
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await expect(doSomethingAsync(1, 2)).resolves.toBe(1);
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})
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`,
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dedent`
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it('pass', async () => {
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await expect(async () => {
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await doSomethingAsync();
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await doSomethingTwiceAsync(1, 2);
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}).rejects.toThrow();
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})
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`,
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{
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code: dedent`
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import { expect as pleaseExpect } from '@jest/globals';
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it('pass', async () => {
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await pleaseExpect(doSomethingAsync()).rejects.toThrow();
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})
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`,
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parserOptions: { sourceType: 'module' },
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},
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dedent`
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it('pass', async () => {
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await expect(async () => {
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doSomethingSync();
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}).rejects.toThrow();
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})
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`,
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],
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invalid: [
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{
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code: dedent`
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it('should be fix', async () => {
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await expect(async () => {
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await doSomethingAsync();
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}).rejects.toThrow();
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})
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`,
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output: dedent`
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it('should be fix', async () => {
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await expect(doSomethingAsync()).rejects.toThrow();
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})
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`,
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errors: [
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{
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endColumn: 6,
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column: 18,
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messageId: 'noAsyncWrapperForExpectedPromise',
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},
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],
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},
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{
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code: dedent`
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it('should be fix', async () => {
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await expect(async function () {
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await doSomethingAsync();
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}).rejects.toThrow();
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})
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`,
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output: dedent`
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it('should be fix', async () => {
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await expect(doSomethingAsync()).rejects.toThrow();
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})
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`,
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errors: [
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{
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endColumn: 6,
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column: 18,
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messageId: 'noAsyncWrapperForExpectedPromise',
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},
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],
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},
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{
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code: dedent`
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it('should be fix', async () => {
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await expect(async () => {
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await doSomethingAsync(1, 2);
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}).rejects.toThrow();
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})
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`,
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output: dedent`
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it('should be fix', async () => {
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await expect(doSomethingAsync(1, 2)).rejects.toThrow();
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})
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`,
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errors: [
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{
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endColumn: 6,
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column: 18,
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messageId: 'noAsyncWrapperForExpectedPromise',
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},
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],
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},
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{
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code: dedent`
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it('should be fix', async () => {
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await expect(async function () {
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await doSomethingAsync(1, 2);
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}).rejects.toThrow();
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})
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`,
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output: dedent`
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it('should be fix', async () => {
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await expect(doSomethingAsync(1, 2)).rejects.toThrow();
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})
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`,
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errors: [
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{
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endColumn: 6,
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column: 18,
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messageId: 'noAsyncWrapperForExpectedPromise',
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},
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],
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},
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],
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});

‎src/rules/no-async-wrapper-for-expected-promise.ts‎

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import { AST_NODE_TYPES, type TSESTree } from '@typescript-eslint/utils';
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import { createRule, parseJestFnCall } from './utils';
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export default createRule({
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name: __filename,
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meta: {
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docs: {
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description:
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'Disallow unnecessary async function wrapper for expected promises',
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},
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fixable: 'code',
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messages: {
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noAsyncWrapperForExpectedPromise:
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'Rejected/resolved promises should not be wrapped in async function',
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},
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schema: [],
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type: 'suggestion',
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},
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defaultOptions: [],
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create(context) {
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return {
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CallExpression(node: TSESTree.CallExpression) {
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const jestFnCall = parseJestFnCall(node, context);
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if (jestFnCall?.type !== 'expect') {
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return;
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}
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const { parent } = jestFnCall.head.node;
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if (parent?.type !== AST_NODE_TYPES.CallExpression) {
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return;
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}
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const [awaitNode] = parent.arguments;
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if (
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(awaitNode?.type !== AST_NODE_TYPES.ArrowFunctionExpression &&
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awaitNode?.type !== AST_NODE_TYPES.FunctionExpression) ||
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!awaitNode?.async ||
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awaitNode.body.type !== AST_NODE_TYPES.BlockStatement ||
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awaitNode.body.body.length !== 1
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) {
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return;
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}
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const [callback] = awaitNode.body.body;
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if (
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callback.type === AST_NODE_TYPES.ExpressionStatement &&
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callback.expression.type === AST_NODE_TYPES.AwaitExpression &&
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callback.expression.argument.type === AST_NODE_TYPES.CallExpression
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) {
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const innerAsyncFuncCall = callback.expression.argument;
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context.report({
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node: awaitNode,
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messageId: 'noAsyncWrapperForExpectedPromise',
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fix(fixer) {
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const { sourceCode } = context;
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return [
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fixer.replaceTextRange(
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[awaitNode.range[0], awaitNode.range[1]],
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sourceCode.getText(innerAsyncFuncCall),
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),
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];
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},
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});
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}
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},
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};
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},
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});

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