1 files changed, 49 insertions, 0 deletions
diff --git a/testing/web-platform/tests/resource-timing/cors-preflight.any.js b/testing/web-platform/tests/resource-timing/cors-preflight.any.js
new file mode 100644
index 0000000000..4b980e7d0a
--- /dev/null
+++ b/testing/web-platform/tests/resource-timing/cors-preflight.any.js
@@ -0,0 +1,49 @@
+// META: script=/common/utils.js
+// META: script=/common/get-host-info.sub.js
+
+// Because apache decrements the Keep-Alive max value on each request, the
+// transferSize will vary slightly between requests for the same resource.
+const fuzzFactor = 3;  // bytes
+
+const {HTTP_REMOTE_ORIGIN} = get_host_info();
+const url = new URL('/resource-timing/resources/preflight.py',
+    HTTP_REMOTE_ORIGIN).href;
+
+// The header bytes are expected to be > |minHeaderSize| and
+// < |maxHeaderSize|. If they are outside this range the test will fail.
+const minHeaderSize = 100;
+const maxHeaderSize = 1024;
+
+promise_test(async () => {
+  const checkCorsAllowed = response => response.arrayBuffer();
+  const requirePreflight = {headers: {'X-Require-Preflight' : '1'}};
+  const collectEntries = new Promise(resolve => {
+    let entriesSeen = [];
+    new PerformanceObserver(entryList => {
+      entriesSeen = entriesSeen.concat(entryList.getEntries());
+      if (entriesSeen.length > 2) {
+        throw new Error(`Saw too many PerformanceResourceTiming entries ` +
+            `(${entriesSeen.length})`);
+      }
+      if (entriesSeen.length == 2) {
+        resolve(entriesSeen);
+      }
+    }).observe({"type": "resource"});
+  });
+
+  // Although this fetch doesn't send a pre-flight request, the server response
+  // will allow cross-origin requests explicitly with the
+  // Access-Control-Allow-Origin header.
+  await fetch(url).then(checkCorsAllowed);
+
+  // This fetch will send a pre-flight request to do the CORS handshake
+  // explicitly.
+  await fetch(url, requirePreflight).then(checkCorsAllowed);
+
+  const entries = await collectEntries;
+  assert_greater_than(entries[0].transferSize, 0, 'No-preflight transferSize');
+  const lowerBound = entries[0].transferSize - fuzzFactor;
+  const upperBound = entries[0].transferSize + fuzzFactor;
+  assert_between_exclusive(entries[1].transferSize, lowerBound, upperBound,
+      'Preflighted transferSize');
+}, 'PerformanceResourceTiming sizes fetch with preflight test');