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Clement398fiskersindresorhus
authoredFeb 23, 2024··
Add no-single-promise-in-promise-methods rule (#2258)
Co-authored-by: fisker <lionkay@gmail.com> Co-authored-by: Sindre Sorhus <sindresorhus@gmail.com>
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v58.0.0v52.0.0
1 parent 1792d33 commit 8f0ee89

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‎configs/recommended.js

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@@ -40,6 +40,7 @@ module.exports = {
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'unicorn/no-null': 'error',
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'unicorn/no-object-as-default-parameter': 'error',
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'unicorn/no-process-exit': 'error',
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'unicorn/no-single-promise-in-promise-methods': 'error',
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'unicorn/no-static-only-class': 'error',
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'unicorn/no-thenable': 'error',
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'unicorn/no-this-assignment': 'error',

‎docs/rules/no-single-promise-in-promise-methods.md

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# Disallow passing single-element arrays to `Promise` methods
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💼 This rule is enabled in the ✅ `recommended` [config](https://github.com/sindresorhus/eslint-plugin-unicorn#preset-configs).
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🔧💡 This rule is automatically fixable by the [`--fix` CLI option](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix) and manually fixable by [editor suggestions](https://eslint.org/docs/developer-guide/working-with-rules#providing-suggestions).
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<!-- end auto-generated rule header -->
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<!-- Do not manually modify this header. Run: `npm run fix:eslint-docs` -->
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Passing a single-element array to `Promise.all()`, `Promise.any()`, or `Promise.race()` is likely a mistake.
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## Fail
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```js
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const foo = await Promise.all([promise]);
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```
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```js
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const foo = await Promise.any([promise]);
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```
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```js
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const foo = await Promise.race([promise]);
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```
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```js
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const promise = Promise.all([nonPromise]);
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```
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## Pass
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```js
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const foo = await promise;
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```
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```js
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const promise = Promise.resolve(nonPromise);
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```
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```js
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const foo = await Promise.all(promises);
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```
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```js
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const foo = await Promise.any([promise, anotherPromise]);
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```
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```js
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const [{value: foo, reason: error}] = await Promise.allSettled([promise]);
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```

‎readme.md

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@@ -148,6 +148,7 @@ If you don't use the preset, ensure you use the same `env` and `parserOptions` c
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| [no-null](docs/rules/no-null.md) | Disallow the use of the `null` literal. | ✅ | 🔧 | 💡 |
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| [no-object-as-default-parameter](docs/rules/no-object-as-default-parameter.md) | Disallow the use of objects as default parameters. | ✅ | | |
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| [no-process-exit](docs/rules/no-process-exit.md) | Disallow `process.exit()`. | ✅ | | |
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| [no-single-promise-in-promise-methods](docs/rules/no-single-promise-in-promise-methods.md) | Disallow passing single-element arrays to `Promise` methods. | ✅ | 🔧 | 💡 |
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| [no-static-only-class](docs/rules/no-static-only-class.md) | Disallow classes that only have static members. | ✅ | 🔧 | |
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| [no-thenable](docs/rules/no-thenable.md) | Disallow `then` property. | ✅ | | |
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| [no-this-assignment](docs/rules/no-this-assignment.md) | Disallow assigning `this` to a variable. | ✅ | | |

‎rules/no-single-promise-in-promise-methods.js

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'use strict';
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const {
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isCommaToken,
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} = require('@eslint-community/eslint-utils');
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const {isMethodCall} = require('./ast/index.js');
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const {
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getParenthesizedText,
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isParenthesized,
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needsSemicolon,
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shouldAddParenthesesToAwaitExpressionArgument,
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} = require('./utils/index.js');
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const MESSAGE_ID_ERROR = 'no-single-promise-in-promise-methods/error';
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const MESSAGE_ID_SUGGESTION_UNWRAP = 'no-single-promise-in-promise-methods/unwrap';
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const MESSAGE_ID_SUGGESTION_SWITCH_TO_PROMISE_RESOLVE = 'no-single-promise-in-promise-methods/use-promise-resolve';
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const messages = {
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[MESSAGE_ID_ERROR]: 'Wrapping single-element array with `Promise.{{method}}()` is unnecessary.',
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[MESSAGE_ID_SUGGESTION_UNWRAP]: 'Use the value directly.',
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[MESSAGE_ID_SUGGESTION_SWITCH_TO_PROMISE_RESOLVE]: 'Switch to `Promise.resolve(…)`.',
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};
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const METHODS = ['all', 'any', 'race'];
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const isPromiseMethodCallWithSingleElementArray = node =>
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isMethodCall(node, {
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object: 'Promise',
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methods: METHODS,
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optionalMember: false,
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optionalCall: false,
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argumentsLength: 1,
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})
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&& node.arguments[0].type === 'ArrayExpression'
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&& node.arguments[0].elements.length === 1
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&& node.arguments[0].elements[0]
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&& node.arguments[0].elements[0].type !== 'SpreadElement';
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const unwrapAwaitedCallExpression = (callExpression, sourceCode) => fixer => {
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const [promiseNode] = callExpression.arguments[0].elements;
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let text = getParenthesizedText(promiseNode, sourceCode);
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if (
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!isParenthesized(promiseNode, sourceCode)
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&& shouldAddParenthesesToAwaitExpressionArgument(promiseNode)
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) {
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text = `(${text})`;
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}
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// The next node is already behind a `CallExpression`, there should be no ASI problem
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return fixer.replaceText(callExpression, text);
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};
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const unwrapNonAwaitedCallExpression = (callExpression, sourceCode) => fixer => {
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const [promiseNode] = callExpression.arguments[0].elements;
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let text = getParenthesizedText(promiseNode, sourceCode);
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if (
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!isParenthesized(promiseNode, sourceCode)
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// Since the original call expression can be anywhere, it's hard to tell if the promise
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// need to be parenthesized, but it's safe to add parentheses
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&& !(
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// Known cases that not need parentheses
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promiseNode.type === 'Identifier'
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|| promiseNode.type === 'MemberExpression'
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)
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) {
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text = `(${text})`;
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}
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const previousToken = sourceCode.getTokenBefore(callExpression);
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if (needsSemicolon(previousToken, sourceCode, text)) {
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text = `;${text}`;
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}
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return fixer.replaceText(callExpression, text);
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};
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const switchToPromiseResolve = (callExpression, sourceCode) => function * (fixer) {
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/*
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```
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Promise.all([promise,])
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// ^^^ methodNameNode
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```
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*/
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const methodNameNode = callExpression.callee.property;
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yield fixer.replaceText(methodNameNode, 'resolve');
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const [arrayExpression] = callExpression.arguments;
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/*
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```
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Promise.all([promise,])
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// ^ openingBracketToken
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```
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*/
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const openingBracketToken = sourceCode.getFirstToken(arrayExpression);
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/*
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```
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Promise.all([promise,])
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// ^ penultimateToken
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// ^ closingBracketToken
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```
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*/
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const [
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penultimateToken,
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closingBracketToken,
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] = sourceCode.getLastTokens(arrayExpression, 2);
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yield fixer.remove(openingBracketToken);
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yield fixer.remove(closingBracketToken);
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if (isCommaToken(penultimateToken)) {
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yield fixer.remove(penultimateToken);
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}
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};
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/** @param {import('eslint').Rule.RuleContext} context */
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const create = context => ({
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CallExpression(callExpression) {
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if (!isPromiseMethodCallWithSingleElementArray(callExpression)) {
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return;
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}
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const problem = {
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node: callExpression.arguments[0],
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messageId: MESSAGE_ID_ERROR,
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data: {
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method: callExpression.callee.property.name,
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},
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};
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const {sourceCode} = context;
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if (
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callExpression.parent.type === 'AwaitExpression'
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&& callExpression.parent.argument === callExpression
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) {
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problem.fix = unwrapAwaitedCallExpression(callExpression, sourceCode);
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return problem;
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}
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problem.suggest = [
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{
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messageId: MESSAGE_ID_SUGGESTION_UNWRAP,
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fix: unwrapNonAwaitedCallExpression(callExpression, sourceCode),
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},
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{
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messageId: MESSAGE_ID_SUGGESTION_SWITCH_TO_PROMISE_RESOLVE,
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fix: switchToPromiseResolve(callExpression, sourceCode),
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},
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];
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return problem;
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},
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});
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/** @type {import('eslint').Rule.RuleModule} */
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module.exports = {
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create,
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meta: {
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type: 'suggestion',
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docs: {
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description: 'Disallow passing single-element arrays to `Promise` methods.',
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},
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fixable: 'code',
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hasSuggestions: true,
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messages,
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},
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};

‎rules/utils/index.js

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isValueNotUsable: require('./is-value-not-usable.js'),
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needsSemicolon: require('./needs-semicolon.js'),
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shouldAddParenthesesToMemberExpressionObject: require('./should-add-parentheses-to-member-expression-object.js'),
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shouldAddParenthesesToAwaitExpressionArgument: require('./should-add-parentheses-to-await-expression-argument.js'),
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singular: require('./singular.js'),
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toLocation: require('./to-location.js'),
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getAncestor: require('./get-ancestor.js'),

‎rules/utils/should-add-parentheses-to-await-expression-argument.js

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'use strict';
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/**
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Check if parentheses should be added to a `node` when it's used as `argument` of `AwaitExpression`.
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@param {Node} node - The AST node to check.
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@returns {boolean}
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*/
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function shouldAddParenthesesToAwaitExpressionArgument(node) {
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return (
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node.type === 'SequenceExpression'
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|| node.type === 'YieldExpression'
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|| node.type === 'ArrowFunctionExpression'
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|| node.type === 'ConditionalExpression'
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|| node.type === 'AssignmentExpression'
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|| node.type === 'LogicalExpression'
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|| node.type === 'BinaryExpression'
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);
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}
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module.exports = shouldAddParenthesesToAwaitExpressionArgument;

‎test/no-single-promise-in-promise-methods.mjs

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import outdent from 'outdent';
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import {getTester} from './utils/test.mjs';
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const {test} = getTester(import.meta);
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// `await`ed
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test.snapshot({
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valid: [
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],
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invalid: [
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'await Promise.all([(0, promise)])',
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'async function * foo() {await Promise.all([yield promise])}',
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'async function * foo() {await Promise.all([yield* promise])}',
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'await Promise.all([() => promise,],)',
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'await Promise.all([a ? b : c,],)',
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'await Promise.all([x ??= y,],)',
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'await Promise.all([x ||= y,],)',
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'await Promise.all([x &&= y,],)',
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'await Promise.all([x |= y,],)',
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'await Promise.all([x ^= y,],)',
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'await Promise.all([x ??= y,],)',
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'await Promise.all([x ||= y,],)',
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'await Promise.all([x &&= y,],)',
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'await Promise.all([x | y,],)',
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'await Promise.all([x ^ y,],)',
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'await Promise.all([x & y,],)',
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'await Promise.all([x !== y,],)',
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'await Promise.all([x == y,],)',
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'await Promise.all([x in y,],)',
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'await Promise.all([x >>> y,],)',
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'await Promise.all([x + y,],)',
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'await Promise.all([x / y,],)',
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'await Promise.all([x ** y,],)',
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'await Promise.all([promise,],)',
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'await Promise.all([getPromise(),],)',
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'await Promise.all([promises[0],],)',
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'await Promise.all([await promise])',
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'await Promise.any([promise])',
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'await Promise.race([promise])',
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'await Promise.all([new Promise(() => {})])',
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'+await Promise.all([+1])',
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// ASI, `Promise.all()` is not really `await`ed
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outdent`
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await Promise.all([(x,y)])
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[0].toString()
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`,
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],
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});
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// Not `await`ed
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test.snapshot({
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valid: [
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'Promise.all([promise, anotherPromise])',
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'Promise.all(notArrayLiteral)',
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'Promise.all([...promises])',
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'Promise.any([promise, anotherPromise])',
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'Promise.race([promise, anotherPromise])',
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'Promise.notListedMethod([promise])',
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'Promise[all]([promise])',
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'Promise.all([,])',
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'NotPromise.all([promise])',
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'Promise?.all([promise])',
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'Promise.all?.([promise])',
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'Promise.all(...[promise])',
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'Promise.all([promise], extraArguments)',
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'Promise.all()',
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'new Promise.all([promise])',
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// We are not checking these cases
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'globalThis.Promise.all([promise])',
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'Promise["all"]([promise])',
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// This can't be checked
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'Promise.allSettled([promise])',
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],
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invalid: [
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'Promise.all([promise,],)',
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outdent`
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foo
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Promise.all([(0, promise),],)
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`,
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outdent`
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foo
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Promise.all([[array][0],],)
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`,
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'Promise.all([promise]).then()',
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'Promise.all([1]).then()',
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'Promise.all([1.]).then()',
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'Promise.all([.1]).then()',
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'Promise.all([(0, promise)]).then()',
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'const _ = () => Promise.all([ a ?? b ,],)',
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'Promise.all([ {a} = 1 ,],)',
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'Promise.all([ function () {} ,],)',
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'Promise.all([ class {} ,],)',
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'Promise.all([ new Foo ,],).then()',
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'Promise.all([ new Foo ,],).toString',
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'foo(Promise.all([promise]))',
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'Promise.all([promise]).foo = 1',
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'Promise.all([promise])[0] ||= 1',
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'Promise.all([undefined]).then()',
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'Promise.all([null]).then()',
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],
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});

‎test/snapshots/no-single-promise-in-promise-methods.mjs.md

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‎test/snapshots/no-single-promise-in-promise-methods.mjs.snap

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