From 91ea165d60c26b8ecb6501e2b1a2b434f5dced09 Mon Sep 17 00:00:00 2001
From: Adriana Ixba <ixbaadriana@gmail.com>
Date: Thu, 6 Jul 2023 15:07:37 -0700
Subject: [PATCH] add metric savings

---
 core/audits/prioritize-lcp-image.js           |  3 ++-
 core/test/audits/prioritize-lcp-image-test.js | 12 ++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/core/audits/prioritize-lcp-image.js b/core/audits/prioritize-lcp-image.js
index ca78681bf95e..8f87d79206d1 100644
--- a/core/audits/prioritize-lcp-image.js
+++ b/core/audits/prioritize-lcp-image.js
@@ -244,7 +244,7 @@ class PrioritizeLcpImage extends Audit {
       .find(element => element.traceEventType === 'largest-contentful-paint');
 
     if (!lcpElement || lcpElement.type !== 'image') {
-      return {score: null, notApplicable: true};
+      return {score: null, notApplicable: true, metricSavings: {LCP: 0}};
     }
 
     const mainResource = await MainResource.request({devtoolsLog, URL}, context);
@@ -286,6 +286,7 @@ class PrioritizeLcpImage extends Audit {
       numericUnit: 'millisecond',
       displayValue: wastedMs ? str_(i18n.UIStrings.displayValueMsSavings, {wastedMs}) : '',
       details,
+      metricSavings: {LCP: wastedMs},
     };
   }
 }
diff --git a/core/test/audits/prioritize-lcp-image-test.js b/core/test/audits/prioritize-lcp-image-test.js
index ec5feb894ddb..0fd8b0632983 100644
--- a/core/test/audits/prioritize-lcp-image-test.js
+++ b/core/test/audits/prioritize-lcp-image-test.js
@@ -112,6 +112,7 @@ describe('Performance: prioritize-lcp-image audit', () => {
     expect(result).toEqual({
       score: null,
       notApplicable: true,
+      metricSavings: {LCP: 0},
     });
   });
 
@@ -123,6 +124,7 @@ describe('Performance: prioritize-lcp-image audit', () => {
     expect(result).toEqual({
       score: null,
       notApplicable: true,
+      metricSavings: {LCP: 0},
     });
   });
 
@@ -139,6 +141,7 @@ describe('Performance: prioritize-lcp-image audit', () => {
     expect(results.score).toEqual(1);
     expect(results.details.overallSavingsMs).toEqual(0);
     expect(results.details.items).toHaveLength(0);
+    expect(results.metricSavings).toEqual({LCP: 0});
   });
 
   it('shouldn\'t be applicable if the lcp is already preloaded', async () => {
@@ -149,6 +152,7 @@ describe('Performance: prioritize-lcp-image audit', () => {
     expect(results.score).toEqual(1);
     expect(results.details.overallSavingsMs).toEqual(0);
     expect(results.details.items).toHaveLength(0);
+    expect(results.metricSavings).toEqual({LCP: 0});
 
     // debugData should be included even if image shouldn't be preloaded.
     expect(results.details.debugData).toMatchObject({
@@ -169,6 +173,7 @@ describe('Performance: prioritize-lcp-image audit', () => {
     expect(results.score).toEqual(1);
     expect(results.details.overallSavingsMs).toEqual(0);
     expect(results.details.items).toHaveLength(0);
+    expect(results.metricSavings).toEqual({LCP: 0});
   });
 
   it('should suggest preloading a lcp image if all criteria is met', async () => {
@@ -179,6 +184,7 @@ describe('Performance: prioritize-lcp-image audit', () => {
     expect(results.details.overallSavingsMs).toEqual(30);
     expect(results.details.items[0].url).toEqual(imageUrl);
     expect(results.details.items[0].wastedMs).toEqual(30);
+    expect(results.metricSavings).toEqual({LCP: 30});
 
     expect(results.details.debugData).toMatchObject({
       initiatorPath: [
@@ -207,6 +213,7 @@ describe('Performance: prioritize-lcp-image audit', () => {
       ],
       pathLength: 3,
     });
+    expect(results.metricSavings).toEqual({LCP: 180});
   });
 
   it('should use the initiator path of the first image instance loaded', async () => {
@@ -235,6 +242,7 @@ describe('Performance: prioritize-lcp-image audit', () => {
           pathLength: 2,
         },
       },
+      metricSavings: {LCP: 0},
     });
   });
 
@@ -267,6 +275,7 @@ describe('Performance: prioritize-lcp-image audit', () => {
           pathLength: 3,
         },
       },
+      metricSavings: {LCP: 180},
     });
   });
 
@@ -298,6 +307,7 @@ describe('Performance: prioritize-lcp-image audit', () => {
           pathLength: 3,
         },
       },
+      metricSavings: {LCP: 180},
     });
   });
 
@@ -337,6 +347,7 @@ describe('Performance: prioritize-lcp-image audit', () => {
           pathLength: 4,
         },
       },
+      metricSavings: {LCP: 210},
     });
   });
 
@@ -359,6 +370,7 @@ describe('Performance: prioritize-lcp-image audit', () => {
           pathLength: 2,
         },
       },
+      metricSavings: {LCP: 0},
     });
   });
 });