1 files changed, 53 insertions, 0 deletions
diff --git a/testing/web-platform/tests/xhr/send-sync-blocks-async.htm b/testing/web-platform/tests/xhr/send-sync-blocks-async.htm
new file mode 100644
index 0000000000..74f08a59d6
--- /dev/null
+++ b/testing/web-platform/tests/xhr/send-sync-blocks-async.htm
@@ -0,0 +1,53 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <script src="/resources/testharness.js"></script>
+    <script src="/resources/testharnessreport.js"></script>
+    <title>XMLHttpRequest: sync requests should block events on pending async requests</title>
+</head>
+
+<body>
+    <div id="log"></div>
+
+    <script type="text/javascript">
+        var test = async_test();
+
+        var expect = ['sync 4', 'async 2', 'async 3', 'async 4']
+        var actual = []
+
+        test.step(function()
+        {
+            var xhr_async = new XMLHttpRequest()
+            xhr_async.open('GET', 'resources/delay.py?ms=1000', true) // first launch an async request, completes in 1 second
+            xhr_async.onreadystatechange = test.step_func(() => {
+                actual.push('async ' + xhr_async.readyState)
+                if(xhr_async.readyState === 4 && actual.indexOf('sync 4')>-1){
+                    VerifyResult()
+                }
+            });
+            xhr_async.send()
+
+            test.step_timeout(() => {
+                var xhr_sync = new XMLHttpRequest();
+                xhr_sync.open('GET', 'resources/delay.py?ms=2000', false) // here's a sync request that will take 2 seconds to finish
+                xhr_sync.onreadystatechange = test.step_func(() => {
+                    actual.push('sync ' + xhr_sync.readyState)
+                    if(xhr_sync.readyState === 4 && actual.indexOf('async 4')>-1){
+                        VerifyResult()
+                    }
+                });
+                xhr_sync.send()
+            }, 10);
+
+            function VerifyResult()
+            {
+                test.step(function()
+                {
+                    assert_array_equals(actual, expect);
+                    test.done();
+                });
+            };
+        });
+    </script>
+</body>
+</html>