lib: resolve sources of index source maps

lib/internal/source_map/source_map_cache.js

@@ -1,6 +1,7 @@
 'use strict';
 
 const {
+  ArrayPrototypeIncludes,
   ArrayPrototypeIndexOf,
   ArrayPrototypePush,
   JSONParse,
@@ -338,6 +339,12 @@ function sourceMapFromDataUrl(sourceURL, url) {
 // src in a html document).
 // If the sources are absolute paths, the sources are converted to absolute file URLs.
 function sourcesToAbsolute(baseURL, data) {
+  if (data.sections) {
+    for (let i = 0; i < data.sections.length; ++i) {
+      sourcesToAbsolute(baseURL, data.sections[i].map);
+    }
+    return data;
+  }
   data.sources = data.sources.map((source) => {
     source = (data.sourceRoot || '') + source;
     if (isAbsolute(source)) {
@@ -443,6 +450,15 @@ function findSourceMap(sourceURL) {
  * @returns {string | undefined} - the source content or undefined if file not found
  */
 function getOriginalSource(payload, originalSourcePath) {
+  if (payload.sections) {
+    for (let i = 0; i < payload.sections.length; ++i) {
+      const { map } = payload.sections[i];
+      if (ArrayPrototypeIncludes(map.sources, originalSourcePath)) {
+        return getOriginalSource(map, originalSourcePath);
+      }
+    }
+    return;
+  }
   let source;
   // payload.sources has been normalized to be an array of absolute urls.
   const sourceContentIndex =

lib/internal/test_runner/coverage.js

@@ -494,12 +494,16 @@ class TestCoverage {
         offset += length + 1;
         return coverageLine;
       });
-      for (let j = 0; j < data.sources.length; ++j) {
-        const source = data.sourcesContent?.[j];
-        if (source != null) {
-          this.getLines(data.sources[j], source);
+      const maps = data.sections ? ArrayPrototypeMap(data.sections, (section) => section.map) : [data];
+      for (let m = 0; m < maps.length; ++m) {
+        const { sources, sourcesContent } = maps[m];
+        for (let j = 0; j < sources.length; ++j) {
+          const source = sourcesContent?.[j];
+          if (source != null) {
+            this.getLines(sources[j], source);
+          }
+          this.markTypeScriptOnlyLines(sources[j], source);
         }
-        this.markTypeScriptOnlyLines(data.sources[j], source);
       }
       const sourceMap = new SourceMap(data, { __proto__: null, lineLengths });
 

test/parallel/test-runner-coverage-source-map.js

@@ -123,6 +123,31 @@ describe('Coverage with source maps', async () => {
     t.assert.strictEqual(spawned.code, 0);
   });
 
+  await it('should work with index source maps', async (t) => {
+    const report = generateReport([
+      '# -----------------------------------------------------------------',
+      '# file             | line % | branch % | funcs % | uncovered lines',
+      '# -----------------------------------------------------------------',
+      '# test             |        |          |         | ',
+      '#  fixtures        |        |          |         | ',
+      '#   test-runner    |        |          |         | ',
+      '#    source-maps   |        |          |         | ',
+      '#     index-map    |        |          |         | ',
+      '#      index.ts    | 100.00 |   100.00 |  100.00 | ',
+      '# -----------------------------------------------------------------',
+      '# all files        | 100.00 |   100.00 |  100.00 | ',
+      '# -----------------------------------------------------------------',
+    ]);
+
+    const spawned = await common.spawnPromisified(process.execPath, [
+      ...flags,
+      fixtures.path('test-runner', 'source-maps', 'index-map', 'index.js'),
+    ]);
+    t.assert.strictEqual(spawned.stderr, '');
+    t.assert.ok(spawned.stdout.includes(report));
+    t.assert.strictEqual(spawned.code, 0);
+  });
+
   await it('should throw when a source map is missing a source file', async (t) => {
     const file = fixtures.path('test-runner', 'source-maps', 'missing-sources', 'index.js');
     const missing = fixtures.path('test-runner', 'source-maps', 'missing-sources', 'nonexistent.js');

test/parallel/test-source-map-enable.js

@@ -216,6 +216,29 @@ function nextdir() {
   );
 }
 
+// Applies index source-maps to stack trace.
+{
+  const output = spawnSync(process.execPath, [
+    '--enable-source-maps',
+    require.resolve('../fixtures/source-map/index-map.js'),
+  ]);
+  assert.match(
+    output.stderr.toString(),
+    /at fail \([^)]+index-map-original\.js:2:1\)/
+  );
+  assert.match(output.stderr.toString(), /throw new Error\('original'\);\r?\n\^/);
+}
+
+// Does not throw when an index source-map has no mapping for a position.
+{
+  const output = spawnSync(process.execPath, [
+    '--enable-source-maps',
+    require.resolve('../fixtures/source-map/index-map-unmapped.js'),
+  ]);
+  assert.match(output.stderr.toString(), /AssertionError/);
+  assert.doesNotMatch(output.stderr.toString(), /TypeError/);
+}
+
 // Applies source-maps in esm modules to stack trace.
 {
   const output = spawnSync(process.execPath, [