test: add test for WrapStream readStop

PR-URL: nodejs/node#16356
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>

test/parallel/test-wrap-js-stream-read-stop.js

@@ -0,0 +1,42 @@
+// Flags: --expose-internals
+'use strict';
+
+require('../common');
+const assert = require('assert');
+const WrapStream = require('internal/wrap_js_stream');
+const Stream = require('stream');
+
+class FakeStream extends Stream {
+  constructor() {
+    super();
+    this._paused = false;
+  }
+
+  pause() {
+    this._paused = true;
+  }
+
+  resume() {
+    this._paused = false;
+  }
+
+  isPaused() {
+    return this._paused;
+  }
+}
+
+const fakeStreamObj = new FakeStream();
+const wrappedStream = new WrapStream(fakeStreamObj);
+
+// Resume by wrapped stream upon construction
+assert.strictEqual(fakeStreamObj.isPaused(), false);
+
+fakeStreamObj.pause();
+
+assert.strictEqual(fakeStreamObj.isPaused(), true);
+
+fakeStreamObj.resume();
+
+assert.strictEqual(wrappedStream.readStop(), 0);
+
+assert.strictEqual(fakeStreamObj.isPaused(), true);