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feat(eslint-plugin): [await-thenable] check Promise.all #10282

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feat(eslint-plugin): [await-thenable] check Promise.all #10282

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74cf4b7
fix: await-thenable
Zamiell Nov 4, 2024
da7cdb5
update
Zamiell Nov 4, 2024
813b1b8
Merge branch 'main' into fix-await-thenable
Zamiell Nov 4, 2024
676d2a2
update
Zamiell Nov 4, 2024
55513d4
Merge branch 'main' into fix-await-thenable
Zamiell Nov 6, 2024
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52 changes: 52 additions & 0 deletions packages/eslint-plugin/src/rules/await-thenable.ts
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Original file line number Diff line number Diff line change
@@ -1,5 +1,7 @@
import type { TSESLint, TSESTree } from '@typescript-eslint/utils';
import type * as ts from 'typescript';

import { AST_NODE_TYPES } from '@typescript-eslint/utils';
import * as tsutils from 'ts-api-utils';

import {
Expand All @@ -8,6 +10,7 @@
getParserServices,
isAwaitKeyword,
isTypeAnyType,
isTypeReferenceType,
isTypeUnknownType,
nullThrows,
NullThrowsReasons,
Expand All @@ -19,6 +22,7 @@
| 'awaitUsingOfNonAsyncDisposable'
| 'convertToOrdinaryFor'
| 'forAwaitOfNonAsyncIterable'
| 'notPromises'
| 'removeAwait';

export default createRule<[], MessageId>({
Expand All @@ -38,6 +42,7 @@
convertToOrdinaryFor: 'Convert to an ordinary `for...of` loop.',
forAwaitOfNonAsyncIterable:
'Unexpected `for await...of` of a value that is not async iterable.',
notPromises: 'Unexpected non-promise input to Promise.{methodName}.',
removeAwait: 'Remove unnecessary `await`.',
},
schema: [],
Expand Down Expand Up @@ -167,6 +172,53 @@
}
}
},

// Check for e.g. `Promise.all(nonPromises)`
CallExpression(node): void {
if (
node.callee.type === AST_NODE_TYPES.MemberExpression &&
node.callee.object.type === AST_NODE_TYPES.Identifier &&
node.callee.object.name === 'Promise' &&
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The type verification part probably needs to be reviewed, ...

[Bug] Good question. isBuiltinSymbolLike is our standard utility for this. You'll want to use that, and add tests to make sure things coincidentally named Array or Promise don't erroneously trigger this rule.

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@kirkwaiblinger kirkwaiblinger Nov 11, 2024 •
edited
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I think this comment is on the wrong line, see https://github.com/typescript-eslint/typescript-eslint/pull/10282/files#r1836229674

node.callee.property.type === AST_NODE_TYPES.Identifier &&
(node.callee.property.name === 'all' ||
node.callee.property.name === 'allSettled' ||
node.callee.property.name === 'race')
) {
// Get the type of the thing being used in the method call.
const argument = node.arguments[0];
// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
Comment on lines +188 to +189
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[Style] 💡 hint:

Suggested change
const argument = node.arguments[0];
// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
const argument = node.arguments.at(0);

if (argument === undefined) {
return;

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}

const tsNode = services.esTreeNodeToTSNodeMap.get(argument);
const type = checker.getTypeAtLocation(tsNode);
if (!isTypeReferenceType(type) || type.typeArguments === undefined) {
return;

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}

const typeArg = type.typeArguments[0];
// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
if (typeArg === undefined) {
return;

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}

const typeName = getTypeNameSimple(type);
const typeArgName = getTypeNameSimple(typeArg);

if (typeName === 'Array' && typeArgName !== 'Promise') {
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#10282 (comment)

context.report({
loc: node.loc,
messageId: 'notPromises',
});
}
}
},
};
},
});

/** This is a simplified version of the `getTypeName` utility function. */
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[Question] Why use this the existing getTypeName, then?

This might be a moot point if you end up using isBuiltinSymbolLike or one of the functions around it.

function getTypeNameSimple(type: ts.Type): string | undefined {
return type.getSymbol()?.escapedName as string | undefined;
}
35 changes: 35 additions & 0 deletions packages/eslint-plugin/tests/rules/await-thenable.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -278,6 +278,22 @@ async function iterateUsing(arr: Array<AsyncDisposable>) {
}
`,
},
{
code: `
declare const promises: Array<Promise<void>>;
await Promise.all(promises);
await Promise.allSettled(promises);
await Promise.race(promises);
`,
},
{
code: `
declare const promises: Iterable<Promise<void>>;
await Promise.all(promises);
await Promise.allSettled(promises);
await Promise.race(promises);
`,
},
],

invalid: [
Expand Down Expand Up @@ -639,5 +655,24 @@ async function foo() {
},
],
},
{
code: `
declare const booleans: boolean[];
await Promise.all(booleans);
await Promise.allSettled(booleans);
await Promise.race(booleans);
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https://typescript-eslint.io/contributing/pull-requests#granular-unit-tests: one error per invalid case please

`,
errors: [
{
messageId: 'notPromises',
},
{
messageId: 'notPromises',
},
{
messageId: 'notPromises',
},
],
},
],
});
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