test: test streambase already has a consumer

Author: MrJithil

test/parallel/test-whatwg-webstreams-adapters-streambase.js

@@ -65,3 +65,13 @@ const {
   const readable = newReadableStreamFromStreamBase(stream);
   readable.cancel().then(common.mustCall());
 }
+
+{
+  const stream = new JSStream();
+  stream.onread = () => {};
+  assert.throws(() => newReadableStreamFromStreamBase(stream), {
+    code: 'ERR_INVALID_STATE',
+    message: /StreamBase already has a consumer/
+  });
+  stream.emitEOF();
+}

test/parallel/test-whatwg-webstreams-adapters-to-readablewritablepair.js

@@ -248,3 +248,10 @@ const {
   reader.closed.then(common.mustCall());
   writer.close().then(common.mustCall());
 }
+
+{
+  assert.throws(() => newReadableWritablePairFromDuplex(null), {
+    code: 'ERR_INVALID_ARG_TYPE',
+    message: /The "duplex" argument must be an stream\.Duplex/
+  });
+}

test/parallel/test-whatwg-webstreams-adapters-to-streamduplex.js

@@ -164,3 +164,23 @@ const {
 
   duplex.end();
 }
+
+{
+  const transform = { readable: {}, writable: {} };
+  assert.throws(() => newStreamDuplexFromReadableWritablePair(transform), {
+    code: 'ERR_INVALID_ARG_TYPE',
+    message: /The "pair\.readable" property must be an instance of ReadableStream/
+  });
+}
+
+{
+  const transform = {
+    readable: new ReadableStream(),
+    writable: null
+  };
+
+  assert.throws(() => newStreamDuplexFromReadableWritablePair(transform), {
+    code: 'ERR_INVALID_ARG_TYPE',
+    message: /The "pair\.writable" property must be an instance of WritableStream/
+  });
+}