From 990fbcf2f8a62b68cd646374b835824125336aac Mon Sep 17 00:00:00 2001
From: Adam Rice <ricea@chromium.org>
Date: Fri, 8 Sep 2017 14:59:33 +0900
Subject: [PATCH] TransformStream: add a test that start() is called exactly
 once

---
 .../to-upstream-wpts/transform-streams/general.js    | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/reference-implementation/to-upstream-wpts/transform-streams/general.js b/reference-implementation/to-upstream-wpts/transform-streams/general.js
index cee5e9705..fbfdf313a 100644
--- a/reference-implementation/to-upstream-wpts/transform-streams/general.js
+++ b/reference-implementation/to-upstream-wpts/transform-streams/general.js
@@ -411,4 +411,16 @@ promise_test(() => {
   return cancelPromise;
 }, 'close() should throw after readable.cancel()');
 
+promise_test(() => {
+  let calls = 0;
+  new TransformStream({
+    start() {
+      ++calls;
+    }
+  });
+  return flushAsyncEvents().then(() => {
+    assert_equals(calls, 1, 'start() should have been called exactly once');
+  });
+}, 'start() should not be called twice');
+
 done();