stream: fix isErrored/isWritable for WritableStreams

Author: Renegade334

lib/internal/webstreams/writablestream.js

@@ -76,6 +76,8 @@ const {
 
 const {
   kIsClosedPromise,
+  kIsErrored,
+  kIsWritable,
   kControllerErrorFunction,
 } = require('internal/streams/utils');
 
@@ -183,6 +185,14 @@ class WritableStream {
       size);
   }
 
+  get [kIsErrored]() {
+    return this[kState].state === 'errored';
+  }
+
+  get [kIsWritable]() {
+    return this[kState].state === 'writable';
+  }
+
   /**
    * @readonly
    * @type {boolean}

test/parallel/test-whatwg-writablestream.js

@@ -4,6 +4,8 @@
 const common = require('../common');
 const assert = require('assert');
 
+const { isErrored, isWritable } = require('stream');
+
 const {
   WritableStream,
   WritableStreamDefaultController,
@@ -171,6 +173,27 @@ class Sink {
   }));
 }
 
+{
+  const stream = new WritableStream();
+  assert.strictEqual(isWritable(stream), true);
+  stream.close().then(common.mustCall(() => {
+    assert.strictEqual(isWritable(stream), false);
+  }));
+}
+
+{
+  const stream = new WritableStream({
+    write: common.mustCall((chunk, controller) => {
+      controller.error(new Error());
+    })
+  });
+  const writer = stream.getWriter();
+  assert.strictEqual(isErrored(stream), false);
+  writer.write().then(common.mustCall(() => {
+    assert.strictEqual(isErrored(stream), true);
+  }));
+}
+
 {
   assert.throws(() => Reflect.get(WritableStream.prototype, 'locked', {}), {
     code: 'ERR_INVALID_THIS',