1 files changed, 132 insertions, 0 deletions
diff --git a/testing/web-platform/tests/streams/transferable/resources/helpers.js b/testing/web-platform/tests/streams/transferable/resources/helpers.js
new file mode 100644
index 0000000000..12504537f9
--- /dev/null
+++ b/testing/web-platform/tests/streams/transferable/resources/helpers.js
@@ -0,0 +1,132 @@
+'use strict';
+
+(() => {
+  // Create a ReadableStream that will pass the tests in
+  // testTransferredReadableStream(), below.
+  function createOriginalReadableStream() {
+    return new ReadableStream({
+      start(controller) {
+        controller.enqueue('a');
+        controller.close();
+      }
+    });
+  }
+
+  // Common tests to roughly determine that |rs| is a correctly transferred
+  // version of a stream created by createOriginalReadableStream().
+  function testTransferredReadableStream(rs) {
+    assert_equals(rs.constructor, ReadableStream,
+                  'rs should be a ReadableStream in this realm');
+    assert_true(rs instanceof ReadableStream,
+                'instanceof check should pass');
+
+    // Perform a brand-check on |rs| in the process of calling getReader().
+    const reader = ReadableStream.prototype.getReader.call(rs);
+
+    return reader.read().then(({value, done}) => {
+      assert_false(done, 'done should be false');
+      assert_equals(value, 'a', 'value should be "a"');
+      return reader.read();
+    }).then(({done}) => {
+      assert_true(done, 'done should be true');
+    });
+  }
+
+  function testMessage(msg) {
+    assert_array_equals(msg.ports, [], 'there should be no ports in the event');
+    return testTransferredReadableStream(msg.data);
+  }
+
+  function testMessageEvent(target) {
+    return new Promise((resolve, reject) => {
+      target.addEventListener('message', ev => {
+        try {
+          resolve(testMessage(ev));
+        } catch (e) {
+          reject(e);
+        }
+      }, {once: true});
+    });
+  }
+
+  function testMessageEventOrErrorMessage(target) {
+    return new Promise((resolve, reject) => {
+      target.addEventListener('message', ev => {
+        if (typeof ev.data === 'string') {
+          // Assume it's an error message and reject with it.
+          reject(ev.data);
+          return;
+        }
+
+        try {
+          resolve(testMessage(ev));
+        } catch (e) {
+          reject(e);
+        }
+      }, {once: true});
+    });
+  }
+
+  function checkTestResults(target) {
+    return new Promise((resolve, reject) => {
+      target.onmessage = msg => {
+        // testharness.js sends us objects which we need to ignore.
+        if (typeof msg.data !== 'string')
+        return;
+
+        if (msg.data === 'OK') {
+          resolve();
+        } else {
+          reject(msg.data);
+        }
+      };
+    });
+  }
+
+  // These tests assume that a transferred ReadableStream will behave the same
+  // regardless of how it was transferred. This enables us to simply transfer the
+  // stream to ourselves.
+  function createTransferredReadableStream(underlyingSource) {
+    const original = new ReadableStream(underlyingSource);
+    const promise = new Promise((resolve, reject) => {
+      addEventListener('message', msg => {
+        const rs = msg.data;
+        if (rs instanceof ReadableStream) {
+          resolve(rs);
+        } else {
+          reject(new Error(`what is this thing: "${rs}"?`));
+        }
+      }, {once: true});
+    });
+    postMessage(original, '*', [original]);
+    return promise;
+  }
+
+  function recordingTransferredReadableStream(underlyingSource, strategy) {
+    const original = recordingReadableStream(underlyingSource, strategy);
+    const promise = new Promise((resolve, reject) => {
+      addEventListener('message', msg => {
+        const rs = msg.data;
+        if (rs instanceof ReadableStream) {
+          rs.events = original.events;
+          rs.eventsWithoutPulls = original.eventsWithoutPulls;
+          rs.controller = original.controller;
+          resolve(rs);
+        } else {
+          reject(new Error(`what is this thing: "${rs}"?`));
+        }
+      }, {once: true});
+    });
+    postMessage(original, '*', [original]);
+    return promise;
+  }
+
+  self.createOriginalReadableStream = createOriginalReadableStream;
+  self.testMessage = testMessage;
+  self.testMessageEvent = testMessageEvent;
+  self.testMessageEventOrErrorMessage = testMessageEventOrErrorMessage;
+  self.checkTestResults = checkTestResults;
+  self.createTransferredReadableStream = createTransferredReadableStream;
+  self.recordingTransferredReadableStream = recordingTransferredReadableStream;
+
+})();