Add regression test for #66

test/unit/readable-stream/regression.spec.js

@@ -0,0 +1,27 @@
+const { TransformStream } = require('../../../');
+
+describe('ReadableStream regressions', () => {
+  // https://github.com/MattiasBuelens/web-streams-polyfill/issues/66
+  it('#66', async () => {
+    const { readable, writable } = new TransformStream();
+
+    const producer = (async () => {
+      const writer = writable.getWriter();
+      await writer.write('hello');
+      // The async iterator releases its reader lock in the "close steps" of its pending read, which rejects the
+      // reader's closed promise. However, ReadableStreamClose then tries to resolve that same closed promise.
+      // This *should* be ignored (since the promise is already rejected), but instead would cause a TypeError.
+      await writer.close();
+    })();
+
+    const consumer = (async () => {
+      const results = [];
+      for await (const chunk of readable) {
+        results.push(chunk);
+      }
+      expect(results).toEqual(['hello']);
+    })();
+
+    await Promise.all([producer, consumer]);
+  });
+});