[v20.x backport] test_runner: format coverage report for tap reporter

benchmark/perf_hooks/histogram-clone.js

@@ -0,0 +1,24 @@
+'use strict';
+
+const assert = require('assert');
+const common = require('../common.js');
+
+const { createHistogram } = require('perf_hooks');
+
+const bench = common.createBenchmark(main, {
+  n: [1e5],
+});
+
+let _histogram;
+
+function main({ n }) {
+  const histogram = createHistogram();
+
+  bench.start();
+  for (let i = 0; i < n; i++)
+    _histogram = structuredClone(histogram);
+  bench.end(n);
+
+  // Avoid V8 deadcode (elimination)
+  assert.ok(_histogram);
+}

benchmark/perf_hooks/histogram-create.js

@@ -0,0 +1,22 @@
+'use strict';
+
+const assert = require('assert');
+const common = require('../common.js');
+
+const { createHistogram } = require('perf_hooks');
+
+const bench = common.createBenchmark(main, {
+  n: [1e5],
+});
+
+let _histogram;
+
+function main({ n }) {
+  bench.start();
+  for (let i = 0; i < n; i++)
+    _histogram = createHistogram();
+  bench.end(n);
+
+  // Avoid V8 deadcode (elimination)
+  assert.ok(_histogram);
+}

lib/internal/histogram.js

@@ -52,9 +52,13 @@ function isHistogram(object) {
   return object?.[kHandle] !== undefined;
 }
 
+const kSkipThrow = Symbol('kSkipThrow');
+
 class Histogram {
-  constructor() {
-    throw new ERR_ILLEGAL_CONSTRUCTOR();
+  constructor(skipThrowSymbol = undefined) {
+    if (skipThrowSymbol !== kSkipThrow) {
+      throw new ERR_ILLEGAL_CONSTRUCTOR();
+    }
   }
 
   [kInspect](depth, options) {
@@ -242,7 +246,7 @@ class Histogram {
     const handle = this[kHandle];
     return {
       data: { handle },
-      deserializeInfo: 'internal/histogram:internalHistogram',
+      deserializeInfo: 'internal/histogram:ClonedHistogram',
     };
   }
 
@@ -264,8 +268,12 @@ class Histogram {
 }
 
 class RecordableHistogram extends Histogram {
-  constructor() {
-    throw new ERR_ILLEGAL_CONSTRUCTOR();
+  constructor(skipThrowSymbol = undefined) {
+    if (skipThrowSymbol !== kSkipThrow) {
+      throw new ERR_ILLEGAL_CONSTRUCTOR();
+    }
+
+    super(skipThrowSymbol);
   }
 
   /**
@@ -309,7 +317,7 @@ class RecordableHistogram extends Histogram {
     const handle = this[kHandle];
     return {
       data: { handle },
-      deserializeInfo: 'internal/histogram:internalRecordableHistogram',
+      deserializeInfo: 'internal/histogram:ClonedRecordableHistogram',
     };
   }
 
@@ -318,24 +326,32 @@ class RecordableHistogram extends Histogram {
   }
 }
 
-function internalHistogram(handle) {
+function ClonedHistogram(handle) {
   return makeTransferable(ReflectConstruct(
     function() {
       this[kHandle] = handle;
       this[kMap] = new SafeMap();
     }, [], Histogram));
 }
-internalHistogram.prototype[kDeserialize] = () => {};
 
-function internalRecordableHistogram(handle) {
-  return makeTransferable(ReflectConstruct(
-    function() {
-      this[kHandle] = handle;
-      this[kMap] = new SafeMap();
-      this[kRecordable] = true;
-    }, [], RecordableHistogram));
+ClonedHistogram.prototype[kDeserialize] = () => { };
+
+function ClonedRecordableHistogram(handle) {
+  const histogram = new RecordableHistogram(kSkipThrow);
+
+  histogram[kRecordable] = true;
+  histogram[kMap] = new SafeMap();
+  histogram[kHandle] = handle;
+  histogram.constructor = RecordableHistogram;
+
+  return makeTransferable(histogram);
+}
+
+ClonedRecordableHistogram.prototype[kDeserialize] = () => { };
+
+function createRecordableHistogram(handle) {
+  return new ClonedRecordableHistogram(handle);
 }
-internalRecordableHistogram.prototype[kDeserialize] = () => {};
 
 /**
  * @param {{
@@ -361,14 +377,14 @@ function createHistogram(options = kEmptyObject) {
     throw new ERR_INVALID_ARG_VALUE.RangeError('options.highest', highest);
   }
   validateInteger(figures, 'options.figures', 1, 5);
-  return internalRecordableHistogram(new _Histogram(lowest, highest, figures));
+  return createRecordableHistogram(new _Histogram(lowest, highest, figures));
 }
 
 module.exports = {
   Histogram,
   RecordableHistogram,
-  internalHistogram,
-  internalRecordableHistogram,
+  ClonedHistogram,
+  ClonedRecordableHistogram,
   isHistogram,
   kDestroy,
   kHandle,

lib/internal/test_runner/reporter/tap.js

@@ -58,7 +58,7 @@ async function * tapReporter(source) {
         yield `${indent(data.nesting)}# ${tapEscape(data.message)}\n`;
         break;
       case 'test:coverage':
-        yield getCoverageReport(indent(data.nesting), data.summary, '# ', '');
+        yield getCoverageReport(indent(data.nesting), data.summary, '# ', '', true);
         break;
     }
   }

test/parallel/test-performance-function.js

@@ -90,14 +90,20 @@ const {
 }
 
 (async () => {
+  let _deadCode;
+
   const histogram = createHistogram();
-  const m = (a, b = 1) => {};
+  const m = (a, b = 1) => {
+    for (let i = 0; i < 1e3; i++)
+      _deadCode = i;
+  };
   const n = performance.timerify(m, { histogram });
   assert.strictEqual(histogram.max, 0);
   for (let i = 0; i < 10; i++) {
     n();
     await sleep(10);
   }
+  assert.ok(_deadCode >= 0);
   assert.notStrictEqual(histogram.max, 0);
   [1, '', {}, [], false].forEach((histogram) => {
     assert.throws(() => performance.timerify(m, { histogram }), {

test/parallel/test-runner-coverage.js

@@ -22,16 +22,21 @@ function findCoverageFileForPid(pid) {
 }
 
 function getTapCoverageFixtureReport() {
+  /* eslint-disable max-len */
   const report = [
     '# start of coverage report',
-    '# file | line % | branch % | funcs % | uncovered lines',
-    '# test/fixtures/test-runner/coverage.js | 78.65 | 38.46 | 60.00 | 12, ' +
-    '13, 16, 17, 18, 19, 20, 21, 22, 27, 39, 43, 44, 61, 62, 66, 67, 71, 72',
-    '# test/fixtures/test-runner/invalid-tap.js | 100.00 | 100.00 | 100.00 | ',
-    '# test/fixtures/v8-coverage/throw.js | 71.43 | 50.00 | 100.00 | 5, 6',
-    '# all files | 78.35 | 43.75 | 60.00 |',
+    '# -------------------------------------------------------------------------------------------------------------------',
+    '# file                                     | line % | branch % | funcs % | uncovered lines',
+    '# -------------------------------------------------------------------------------------------------------------------',
+    '# test/fixtures/test-runner/coverage.js    |  78.65 |    38.46 |   60.00 | 12-13 16-22 27 39 43-44 61-62 66-67 71-72',
+    '# test/fixtures/test-runner/invalid-tap.js | 100.00 |   100.00 |  100.00 | ',
+    '# test/fixtures/v8-coverage/throw.js       |  71.43 |    50.00 |  100.00 | 5-6',
+    '# -------------------------------------------------------------------------------------------------------------------',
+    '# all files                                |  78.35 |    43.75 |   60.00 |',
+    '# -------------------------------------------------------------------------------------------------------------------',
     '# end of coverage report',
   ].join('\n');
+  /* eslint-enable max-len */
 
   if (common.isWindows) {
     return report.replaceAll('/', '\\');
@@ -88,7 +93,6 @@ test('test tap coverage reporter', skipIfNoInspector, async (t) => {
     const options = { env: { ...process.env, NODE_V8_COVERAGE: tmpdir.path } };
     const result = spawnSync(process.execPath, args, options);
     const report = getTapCoverageFixtureReport();
-
     assert(result.stdout.toString().includes(report));
     assert.strictEqual(result.stderr.toString(), '');
     assert.strictEqual(result.status, 0);
@@ -152,16 +156,16 @@ test('single process coverage is the same with --test', skipIfNoInspector, () =>
 test('coverage is combined for multiple processes', skipIfNoInspector, () => {
   let report = [
     '# start of coverage report',
-    '# file | line % | branch % | funcs % | uncovered lines',
-    '# test/fixtures/v8-coverage/combined_coverage/common.js | 89.86 | ' +
-    '62.50 | 100.00 | 8, 13, 14, 18, 34, 35, 53',
-    '# test/fixtures/v8-coverage/combined_coverage/first.test.js | 83.33 | ' +
-    '100.00 | 50.00 | 5, 6',
-    '# test/fixtures/v8-coverage/combined_coverage/second.test.js | 100.00 ' +
-    '| 100.00 | 100.00 | ',
-    '# test/fixtures/v8-coverage/combined_coverage/third.test.js | 100.00 | ' +
-    '100.00 | 100.00 | ',
-    '# all files | 92.11 | 72.73 | 88.89 |',
+    '# -------------------------------------------------------------------',
+    '# file           | line % | branch % | funcs % | uncovered lines',
+    '# -------------------------------------------------------------------',
+    '# common.js      |  89.86 |    62.50 |  100.00 | 8 13-14 18 34-35 53',
+    '# first.test.js  |  83.33 |   100.00 |   50.00 | 5-6',
+    '# second.test.js | 100.00 |   100.00 |  100.00 | ',
+    '# third.test.js  | 100.00 |   100.00 |  100.00 | ',
+    '# -------------------------------------------------------------------',
+    '# all files      |  92.11 |    72.73 |   88.89 |',
+    '# -------------------------------------------------------------------',
     '# end of coverage report',
   ].join('\n');
 
@@ -171,10 +175,11 @@ test('coverage is combined for multiple processes', skipIfNoInspector, () => {
 
   const fixture = fixtures.path('v8-coverage', 'combined_coverage');
   const args = [
-    '--test', '--experimental-test-coverage', '--test-reporter', 'tap', fixture,
+    '--test', '--experimental-test-coverage', '--test-reporter', 'tap',
   ];
   const result = spawnSync(process.execPath, args, {
-    env: { ...process.env, NODE_TEST_TMPDIR: tmpdir.path }
+    env: { ...process.env, NODE_TEST_TMPDIR: tmpdir.path },
+    cwd: fixture,
   });
 
   assert.strictEqual(result.stderr.toString(), '');