fix(eslint-plugin): [require-await] treat yield* asynciterable as an …

…await (#4125)
typescript-eslint · Nov 17, 2021 · 5a4ce6a · 5a4ce6a
1 parent f99a9a5
commit 5a4ce6a
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Showing 2 changed files with 105 additions and 6 deletions.
diff --git a/packages/eslint-plugin/src/rules/require-await.ts b/packages/eslint-plugin/src/rules/require-await.ts
@@ -115,16 +115,22 @@ export default util.createRule({
       if (node?.argument?.type === AST_NODE_TYPES.Literal) {
         // making this `false` as for literals we don't need to check the definition
         // eg : async function* run() { yield* 1 }
-        scopeInfo.isAsyncYield = false;
+        scopeInfo.isAsyncYield ||= false;
       }
 
       const tsNode = parserServices.esTreeNodeToTSNodeMap.get(node?.argument);
       const type = checker.getTypeAtLocation(tsNode);
-      const symbol = type.getSymbol();
-
-      // async function* test1() {yield* asyncGenerator() }
-      if (symbol?.getName() === 'AsyncGenerator') {
-        scopeInfo.isAsyncYield = true;
+      const typesToCheck = expandUnionOrIntersectionType(type);
+      for (const type of typesToCheck) {
+        const asyncIterator = tsutils.getWellKnownSymbolPropertyOfType(
+          type,
+          'asyncIterator',
+          checker,
+        );
+        if (asyncIterator !== undefined) {
+          scopeInfo.isAsyncYield = true;
+          break;
+        }
       }
     }
 
@@ -230,3 +236,10 @@ function getFunctionHeadLoc(
     end,
   };
 }
+
+function expandUnionOrIntersectionType(type: ts.Type): ts.Type[] {
+  if (type.isUnionOrIntersection()) {
+    return type.types.flatMap(expandUnionOrIntersectionType);
+  }
+  return [type];
+}
diff --git a/packages/eslint-plugin/tests/rules/require-await.test.ts b/packages/eslint-plugin/tests/rules/require-await.test.ts
@@ -159,6 +159,57 @@ async function* asyncGenerator() {
 }
 async function* test1() {
   yield* asyncGenerator();
+}
+    `,
+    `
+async function* asyncGenerator() {
+  await Promise.resolve();
+  yield 1;
+}
+async function* test1() {
+  yield* asyncGenerator();
+  yield* 2;
+}
+    `,
+    `
+async function* test(source: AsyncIterable<any>) {
+  yield* source;
+}
+    `,
+    `
+async function* test(source: Iterable<any> & AsyncIterable<any>) {
+  yield* source;
+}
+    `,
+    `
+async function* test(source: Iterable<any> | AsyncIterable<any>) {
+  yield* source;
+}
+    `,
+    `
+type MyType = {
+  [Symbol.iterator](): Iterator<any>;
+  [Symbol.asyncIterator](): AsyncIterator<any>;
+};
+async function* test(source: MyType) {
+  yield* source;
+}
+    `,
+    `
+type MyType = {
+  [Symbol.asyncIterator]: () => AsyncIterator<any>;
+};
+async function* test(source: MyType) {
+  yield* source;
+}
+    `,
+    `
+type MyFunctionType = () => AsyncIterator<any>;
+type MyType = {
+  [Symbol.asyncIterator]: MyFunctionType;
+};
+async function* test(source: MyType) {
+  yield* source;
 }
     `,
     'const foo: () => void = async function* () {};',
@@ -294,6 +345,41 @@ async function* asyncGenerator() {
     },
     {
       code: `
+async function* asyncGenerator(source: Iterable<any>) {
+  yield* source;
+}
+      `,
+      errors: [
+        {
+          messageId: 'missingAwait',
+          data: {
+            name: "Async generator function 'asyncGenerator'",
+          },
+        },
+      ],
+    },
+    {
+      code: `
+function isAsyncIterable(value: unknown): value is AsyncIterable<any> {
+  return true;
+}
+async function* asyncGenerator(source: Iterable<any> | AsyncIterable<any>) {
+  if (!isAsyncIterable(source)) {
+    yield* source;
+  }
+}
+      `,
+      errors: [
+        {
+          messageId: 'missingAwait',
+          data: {
+            name: "Async generator function 'asyncGenerator'",
+          },
+        },
+      ],
+    },
+    {
+      code: `
 function* syncGenerator() {
   yield 1;
 }