test_runner: use source maps when reporting coverage

PR-URL: #52060
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Chemi Atlow <chemi@atlow.co.il>

Author: MoLow

lib/internal/source_map/source_map.js

@@ -73,6 +73,7 @@ const {
   ArrayPrototypeSort,
   ObjectPrototypeHasOwnProperty,
   StringPrototypeCharAt,
+  Symbol,
 } = primordials;
 
 const { validateObject } = require('internal/validators');
@@ -83,6 +84,8 @@ const VLQ_BASE_SHIFT = 5;
 const VLQ_BASE_MASK = (1 << 5) - 1;
 const VLQ_CONTINUATION_MASK = 1 << 5;
 
+const kMappings = Symbol('kMappings');
+
 class StringCharIterator {
   /**
    * @constructor
@@ -153,6 +156,10 @@ class SourceMap {
     return cloneSourceMapV3(this.#payload);
   }
 
+  get [kMappings]() {
+    return this.#mappings;
+  }
+
   /**
    * @return {number[] | undefined} line lengths of generated source code
    */
@@ -382,5 +389,6 @@ function compareSourceMapEntry(entry1, entry2) {
 }
 
 module.exports = {
+  kMappings,
   SourceMap,
 };

lib/internal/test_runner/coverage.js

@@ -0,0 +1,13 @@
+The files in the directory are generated by the
+following commands:
+
+```sh
+npx esbuild a.test.ts --sourcemap --outdir=. --out-extension:.js=.mjs --sources-content=false --minify --bundle --platform=node --format=esm
+echo "import { test } from 'node:test';
+test('ok', () => {});
+
+function uncovered() {
+  return 'uncovered';
+}
+" | npx esbuild --sourcemap --sourcefile=stdin.test.ts --sources-content=true --bundle --platform=node --outfile="stdin.test.js"
+```

test/fixtures/test-runner/coverage/README.md

@@ -0,0 +1,2 @@
+import{test as o}from"node:test";import{strictEqual as r}from"node:assert";function e(){r(1,2)}o("fails",()=>{e()});
+//# sourceMappingURL=a.test.mjs.map

test/fixtures/test-runner/coverage/a.test.mjs

@@ -0,0 +1,6 @@
+{
+  "version": 3,
+  "sources": ["a.test.ts", "b.test.ts"],
+  "mappings": "AAAA,OAAS,QAAAA,MAAY,YCArB,OAAS,eAAAC,MAAmB,cAErB,SAASC,GAAU,CACxBD,EAAY,EAAG,CAAC,CAClB,CDDAE,EAAK,QAAS,IAAM,CAClBC,EAAQ,CACV,CAAC",
+  "names": ["test", "strictEqual", "covered", "test", "covered"]
+}

test/fixtures/test-runner/coverage/a.test.mjs.map

@@ -0,0 +1,13 @@
+import { test } from 'node:test';
+import { covered } from './b.test';
+
+test('fails', () => {
+  covered();
+});
+
+function uncovered() {
+  return 'uncovered';
+}
+if (false) {
+  uncovered();
+}

test/fixtures/test-runner/coverage/a.test.ts

@@ -0,0 +1,9 @@
+import { strictEqual } from 'node:assert';
+
+export function covered() {
+  strictEqual(1, 2);
+}
+
+export function uncovered() {
+  return 'uncovered';
+}

test/fixtures/test-runner/coverage/b.test.ts

@@ -0,0 +1,7 @@
+'use strict';
+
+const test = require('node:test');
+test('no soucre map', () => {});
+if (false) {
+  console.log('this does not execute');
+}

test/fixtures/test-runner/coverage/index.test.js

@@ -242,3 +242,34 @@ test('coverage reports on lines, functions, and branches', skipIfNoInspector, as
     });
   });
 });
+
+test('coverage with source maps', skipIfNoInspector, () => {
+  let report = [
+    '# start of coverage report',
+    '# --------------------------------------------------------------',
+    '# file          | line % | branch % | funcs % | uncovered lines',
+    '# --------------------------------------------------------------',
+    '# a.test.ts     |  53.85 |   100.00 |  100.00 | 8-13',  // part of a bundle
+    '# b.test.ts     |  55.56 |   100.00 |  100.00 | 1 7-9', // part of a bundle
+    '# index.test.js |  71.43 |    66.67 |  100.00 | 6-7',  // no source map
+    '# stdin.test.ts |  57.14 |   100.00 |  100.00 | 4-6',  // Source map without original file
+    '# --------------------------------------------------------------',
+    '# all files     |  58.33 |    87.50 |  100.00 |',
+    '# --------------------------------------------------------------',
+    '# end of coverage report',
+  ].join('\n');
+
+  if (common.isWindows) {
+    report = report.replaceAll('/', '\\');
+  }
+
+  const fixture = fixtures.path('test-runner', 'coverage');
+  const args = [
+    '--test', '--experimental-test-coverage', '--test-reporter', 'tap',
+  ];
+  const result = spawnSync(process.execPath, args, { cwd: fixture });
+
+  assert.strictEqual(result.stderr.toString(), '');
+  assert(result.stdout.toString().includes(report));
+  assert.strictEqual(result.status, 1);
+});