From ec5434914f0657aa97dd2cc741f1f9183abc5c03 Mon Sep 17 00:00:00 2001
From: "Kamat, Trivikram" <16024985+trivikr@users.noreply.github.com>
Date: Sun, 21 Jun 2026 13:21:50 -0700
Subject: [PATCH 1/2] test: improve lcov reporter snapshot diagnostics

Propagate failures from the nested LCOV reporter fixture process and
make missing LCOV records fail with a targeted assertion instead of
comparing against blank transformed output.

Signed-off-by: Kamat, Trivikram <16024985+trivikr@users.noreply.github.com>
Assisted-by: openai:gpt-5.5
---
 test/common/assertSnapshot.js                    | 16 ++++++++++++++++
 .../fixtures/test-runner/output/lcov_reporter.js | 15 ++++++++++++++-
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/test/common/assertSnapshot.js b/test/common/assertSnapshot.js
index 9a7482020e098a..8ea40d4887f998 100644
--- a/test/common/assertSnapshot.js
+++ b/test/common/assertSnapshot.js
@@ -238,9 +238,25 @@ function pickTestFileFromLcov(str) {
   const firstLineOfTestFile = lines.findIndex(
     (line) => line.startsWith('SF:') && line.trim().endsWith('output.js'),
   );
+
+  if (firstLineOfTestFile === -1) {
+    assert.fail(
+      'Could not find coverage for test/fixtures/test-runner/output/output.js ' +
+      `in LCOV output:\n${str || '<empty>'}`,
+    );
+  }
+
   const lastLineOfTestFile = lines.findIndex(
     (line, index) => index > firstLineOfTestFile && line.trim() === 'end_of_record',
   );
+
+  if (lastLineOfTestFile === -1) {
+    assert.fail(
+      'Could not find end_of_record for test/fixtures/test-runner/output/output.js ' +
+      `in LCOV output:\n${str}`,
+    );
+  }
+
   return (
     lines[0] + '\n' + lines.slice(firstLineOfTestFile, lastLineOfTestFile + 1).join('\n') + '\n'
   );
diff --git a/test/fixtures/test-runner/output/lcov_reporter.js b/test/fixtures/test-runner/output/lcov_reporter.js
index 832b5d2247965c..97919cb5c4c81f 100644
--- a/test/fixtures/test-runner/output/lcov_reporter.js
+++ b/test/fixtures/test-runner/output/lcov_reporter.js
@@ -3,7 +3,7 @@ require('../../../common');
 const fixtures = require('../../../common/fixtures');
 const spawn = require('node:child_process').spawn;
 
-spawn(
+const child = spawn(
   process.execPath,
   [
     '--no-warnings',
@@ -14,3 +14,16 @@ spawn(
   ],
   { stdio: 'inherit' },
 );
+
+child.on('error', (err) => {
+  throw err;
+});
+
+child.on('exit', (code, signal) => {
+  if (signal) {
+    process.kill(process.pid, signal);
+    return;
+  }
+
+  process.exitCode = code ?? 1;
+});

From 2f1b5611652545c69ec1f49e27ae0d99b17dfcdb Mon Sep 17 00:00:00 2001
From: "Kamat, Trivikram" <16024985+trivikr@users.noreply.github.com>
Date: Sun, 21 Jun 2026 13:30:15 -0700
Subject: [PATCH 2/2] test: avoid hardcoded path in lcov diagnostic

---
 test/common/assertSnapshot.js | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/test/common/assertSnapshot.js b/test/common/assertSnapshot.js
index 8ea40d4887f998..d1ec30bfb78c6a 100644
--- a/test/common/assertSnapshot.js
+++ b/test/common/assertSnapshot.js
@@ -234,14 +234,15 @@ function replaceJunitDuration(str) {
 // This transform picks only the first line and then the lines from the test
 // file.
 function pickTestFileFromLcov(str) {
+  const expectedFile = 'output.js';
   const lines = str.split(/\n/);
   const firstLineOfTestFile = lines.findIndex(
-    (line) => line.startsWith('SF:') && line.trim().endsWith('output.js'),
+    (line) => line.startsWith('SF:') && line.trim().endsWith(expectedFile),
   );
 
   if (firstLineOfTestFile === -1) {
     assert.fail(
-      'Could not find coverage for test/fixtures/test-runner/output/output.js ' +
+      `Could not find LCOV source record ending with ${expectedFile} ` +
       `in LCOV output:\n${str || '<empty>'}`,
     );
   }
@@ -252,7 +253,7 @@ function pickTestFileFromLcov(str) {
 
   if (lastLineOfTestFile === -1) {
     assert.fail(
-      'Could not find end_of_record for test/fixtures/test-runner/output/output.js ' +
+      `Could not find end_of_record for LCOV source record ending with ${expectedFile} ` +
       `in LCOV output:\n${str}`,
     );
   }