replace with hand-crafted async generator for node v20

Author: yaacovCR

src/execution/__tests__/mapAsyncIterable-test.ts

@@ -360,20 +360,37 @@ describe('mapAsyncIterable', () => {
     );
   });
 
-  it('disposes of async iterable', async () => {
+  it('disposes of async generator', async () => {
     let returned = false;
-    async function* source() {
-      try {
-        yield 1;
-        yield 2;
-        yield 3;
-      } finally {
+
+    const items = [1, 2, 3];
+    const generator: AsyncGenerator<number, void, void> = {
+      [Symbol.asyncIterator]() {
+        return this;
+      },
+      next(): Promise<IteratorResult<number, void>> {
+        const value = items.shift();
+        if (value !== undefined) {
+          return Promise.resolve({ done: false, value });
+        }
+
+        return Promise.resolve({ done: true, value: undefined });
+      },
+      return(): Promise<IteratorResult<number, void>> {
         returned = true;
-      }
-    }
+        return Promise.resolve({ done: true, value: undefined });
+      },
+      throw(): Promise<IteratorResult<number, void>> {
+        returned = true;
+        return Promise.reject(new Error());
+      },
+      async [Symbol.asyncDispose]() {
+        await this.return();
+      },
+    };
 
     {
-      await using doubles = mapAsyncIterable(source(), (x) => x + x);
+      await using doubles = mapAsyncIterable(generator, (x) => x + x);
 
       expect(await doubles.next()).to.deep.equal({ value: 2, done: false });
       expect(await doubles.next()).to.deep.equal({ value: 4, done: false });