test_runner: ignore unmapped lines for coverage

lib/internal/test_runner/coverage.js

@@ -1,6 +1,7 @@
 'use strict';
 const {
   ArrayFrom,
+  ArrayPrototypeForEach,
   ArrayPrototypeMap,
   ArrayPrototypePush,
   JSONParse,
@@ -56,12 +57,21 @@ class CoverageLine {
 }
 
 class TestCoverage {
-  constructor(coverageDirectory, originalCoverageDirectory, workingDirectory, excludeGlobs, includeGlobs, thresholds) {
+  constructor(
+    coverageDirectory,
+    originalCoverageDirectory,
+    workingDirectory,
+    excludeGlobs,
+    includeGlobs,
+    sourceMaps,
+    thresholds,
+  ) {
     this.coverageDirectory = coverageDirectory;
     this.originalCoverageDirectory = originalCoverageDirectory;
     this.workingDirectory = workingDirectory;
     this.excludeGlobs = excludeGlobs;
     this.includeGlobs = includeGlobs;
+    this.sourceMaps = sourceMaps;
     this.thresholds = thresholds;
   }
 
@@ -364,7 +374,13 @@ class TestCoverage {
           this.getLines(data.sources[j], data.sourcesContent[j]);
         }
       }
+
       const sourceMap = new SourceMap(data, { __proto__: null, lineLengths });
+      const linesToCover = new SafeSet();
+
+      for (let i = 0; i < sourceMap[kMappings].length; i++) {
+        linesToCover.add(sourceMap[kMappings][i][3] + 1);
+      }
 
       for (let j = 0; j < functions.length; ++j) {
         const { ranges, functionName, isBlockCoverage } = functions[j];
@@ -413,6 +429,15 @@ class TestCoverage {
           // No mappable ranges. Skip the function.
           continue;
         }
+
+        if (this.sourceMaps) {
+          ArrayPrototypeForEach(this.getLines(newUrl), (mappedLine) => {
+            if (!linesToCover.has(mappedLine.line)) {
+              mappedLine.ignore = true;
+            }
+          });
+        }
+
         const newScript = newResult.get(newUrl) ?? { __proto__: null, url: newUrl, functions: [] };
         ArrayPrototypePush(newScript.functions, { __proto__: null, functionName, ranges: newRanges, isBlockCoverage });
         newResult.set(newUrl, newScript);
@@ -514,6 +539,7 @@ function setupCoverage(options) {
     options.cwd,
     options.coverageExcludeGlobs,
     options.coverageIncludeGlobs,
+    options.sourceMaps,
     {
       __proto__: null,
       line: options.lineCoverage,