From 5c522a993f4bd8dc33f28797247004aae03ad5aa Mon Sep 17 00:00:00 2001
From: Barry Pollard <barrypollard@google.com>
Date: Tue, 15 Apr 2025 15:23:00 +0100
Subject: [PATCH 1/3] Add 103 Early Hints test

---
 test/e2e/onTTFB-test.js | 29 +++++++++++++++++++++++++++++
 test/server.js          | 13 +++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/test/e2e/onTTFB-test.js b/test/e2e/onTTFB-test.js
index 07e34fb1..e22affba 100644
--- a/test/e2e/onTTFB-test.js
+++ b/test/e2e/onTTFB-test.js
@@ -398,6 +398,35 @@ describe('onTTFB()', async function () {
       assert.strictEqual(ttfb.attribution.requestDuration, 0);
       assert.strictEqual(ttfb.attribution.navigationEntry, undefined);
     });
+
+    it('reports the correct value for Early Hints', async function () {
+      await navigateTo(
+        // '/test/ttfb?responseStart=10&earlyHintsDelay=50&attribution=1',
+        '/test/ttfb?earlyHintsDelay=50&attribution=1',
+      );
+
+      const ttfb = await getTTFBBeacon();
+
+      if ('finalResponseHeadersStart' in ttfb.attribution.navigationEntry) {
+        assert.strictEqual(
+          ttfb.value,
+          ttfb.attribution.navigationEntry.responseStart,
+        );
+        assert.strictEqual(
+          ttfb.value,
+          ttfb.attribution.navigationEntry.firstInterimResponseStart,
+        );
+        assert(
+          ttfb.value <
+            ttfb.attribution.navigationEntry.finalResponseHeadersStart,
+        );
+      } else {
+        assert.strictEqual(
+          ttfb.value,
+          ttfb.attribution.navigationEntry.responseStart,
+        );
+      }
+    });
   });
 });
 
diff --git a/test/server.js b/test/server.js
index ff666576..5d13d4b0 100644
--- a/test/server.js
+++ b/test/server.js
@@ -39,6 +39,19 @@ app.use((req, res, next) => {
   }
 });
 
+// Allow the use of a `earlyHintsDelay` query param to delay any response
+// after sending an early hints
+app.use((req, res, next) => {
+  if (req.query && req.query.earlyHintsDelay) {
+    res.writeEarlyHints({
+      'link': '</styles.css>; rel=preload; as=style',
+    });
+    setTimeout(next, req.query.earlyHintsDelay);
+  } else {
+    next();
+  }
+});
+
 // Add a "collect" endpoint to simulate analytics beacons.
 app.post('/collect', bodyParser.text(), (req, res) => {
   // Uncomment to log the metric when manually testing.

From c701eda164bebcb96f6d94873e131be9ceaa6cd2 Mon Sep 17 00:00:00 2001
From: Barry Pollard <barrypollard@google.com>
Date: Thu, 17 Apr 2025 18:43:33 +0100
Subject: [PATCH 2/3] Update test/e2e/onTTFB-test.js

---
 test/e2e/onTTFB-test.js | 1 -
 1 file changed, 1 deletion(-)

diff --git a/test/e2e/onTTFB-test.js b/test/e2e/onTTFB-test.js
index e22affba..6ea396ee 100644
--- a/test/e2e/onTTFB-test.js
+++ b/test/e2e/onTTFB-test.js
@@ -401,7 +401,6 @@ describe('onTTFB()', async function () {
 
     it('reports the correct value for Early Hints', async function () {
       await navigateTo(
-        // '/test/ttfb?responseStart=10&earlyHintsDelay=50&attribution=1',
         '/test/ttfb?earlyHintsDelay=50&attribution=1',
       );
 

From e8171f30b03325f5a3d8e3f6a6c827c3873fd434 Mon Sep 17 00:00:00 2001
From: Barry Pollard <barrypollard@google.com>
Date: Thu, 17 Apr 2025 18:44:41 +0100
Subject: [PATCH 3/3] Update test/e2e/onTTFB-test.js

---
 test/e2e/onTTFB-test.js | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/test/e2e/onTTFB-test.js b/test/e2e/onTTFB-test.js
index 6ea396ee..76d9983e 100644
--- a/test/e2e/onTTFB-test.js
+++ b/test/e2e/onTTFB-test.js
@@ -400,9 +400,7 @@ describe('onTTFB()', async function () {
     });
 
     it('reports the correct value for Early Hints', async function () {
-      await navigateTo(
-        '/test/ttfb?earlyHintsDelay=50&attribution=1',
-      );
+      await navigateTo('/test/ttfb?earlyHintsDelay=50&attribution=1');
 
       const ttfb = await getTTFBBeacon();