test_runner: add code coverage support to spec reporter

lib/internal/test_runner/reporter/spec.js

@@ -6,6 +6,7 @@ const {
   ArrayPrototypeShift,
   ArrayPrototypeUnshift,
   hardenRegExp,
+  NumberPrototypeToFixed,
   RegExpPrototypeSymbolSplit,
   SafeMap,
   StringPrototypeRepeat,
@@ -14,6 +15,7 @@ const assert = require('assert');
 const Transform = require('internal/streams/transform');
 const { inspectWithNoCustomRetry } = require('internal/errors');
 const { green, blue, red, white, gray } = require('internal/util/colors');
+const { relative } = require('path');
 
 
 const inspectOptions = { __proto__: null, colors: true, breakLength: Infinity };
@@ -29,6 +31,7 @@ const symbols = {
   'test:fail': '\u2716 ',
   'test:pass': '\u2714 ',
   'test:diagnostic': '\u2139 ',
+  'test:coverage': '\u2139 ',
   'arrow:right': '\u25B6 ',
   'hyphen:minus': '\uFE63 ',
 };
@@ -60,6 +63,39 @@ class SpecReporter extends Transform {
       ), `\n${indent}  `);
     return `\n${indent}  ${message}\n`;
   }
+  #coverageThresholdColor(coverage, color = blue) {
+    coverage = NumberPrototypeToFixed(coverage, 2);
+    if (coverage > 90) return `${green}${coverage}${color}`;
+    if (coverage < 50) return `${red}${coverage}${color}`;
+    return coverage;
+  }
+  #reportCoverage(nesting, symbol, color, summary) {
+    const indent = this.#indent(nesting);
+    let report = `${color}${indent}${symbol}========= coverage report =========\n`;
+    report += `${indent}${symbol}file | line % | branch % | funcs % | uncovered lines\n`;
+    for (let i = 0; i < summary.files.length; ++i) {
+      const {
+        path,
+        coveredLinePercent,
+        coveredBranchPercent,
+        coveredFunctionPercent,
+        uncoveredLineNumbers,
+      } = summary.files[i];
+      const relativePath = relative(summary.workingDirectory, path);
+      const uncovered = ArrayPrototypeJoin(uncoveredLineNumbers, ', ');
+      report += `${indent}${symbol}${relativePath} | ${this.#coverageThresholdColor(coveredLinePercent)} | ${this.#coverageThresholdColor(coveredBranchPercent)} | ` +
+      `${this.#coverageThresholdColor(coveredFunctionPercent)} | ${gray}${uncovered}${color}\n`;
+    }
+    const {
+      coveredLinePercent,
+      coveredBranchPercent,
+      coveredFunctionPercent,
+    } = summary.totals;
+    report += `${indent}${symbol}all files | ${this.#coverageThresholdColor(coveredLinePercent)} | ${this.#coverageThresholdColor(coveredBranchPercent)} | ` +
+    `${this.#coverageThresholdColor(coveredFunctionPercent)} |\n`;
+    report += `${symbol}${indent}==================================== ${white}`
+    return report;
+  }
   #handleEvent({ type, data }) {
     let color = colors[type] ?? white;
     let symbol = symbols[type] ?? ' ';
@@ -103,6 +139,8 @@ class SpecReporter extends Transform {
         break;
       case 'test:diagnostic':
         return `${color}${this.#indent(data.nesting)}${symbol}${data.message}${white}\n`;
+      case 'test:coverage':
+        return this.#reportCoverage(data.nesting, symbols['test:coverage'], blue, data.summary);
     }
   }
   _transform({ type, data }, encoding, callback) {

test/parallel/test-runner-spec-coverage.js

@@ -0,0 +1,70 @@
+'use strict';
+const common = require('../common');
+const assert = require('node:assert');
+const { spawnSync } = require('node:child_process');
+const { readdirSync } = require('node:fs');
+const { test } = require('node:test');
+const fixtures = require('../common/fixtures');
+const tmpdir = require('../common/tmpdir');
+
+tmpdir.refresh();
+
+function findCoverageFileForPid(pid) {
+  const pattern = `^coverage\\-${pid}\\-(\\d{13})\\-(\\d+)\\.json$`;
+  const regex = new RegExp(pattern);
+
+  return readdirSync(tmpdir.path).find((file) => {
+    return regex.test(file);
+  });
+}
+
+function getCoverageFixtureReport() {
+  const report = [
+    '\u2139 ========= coverage report =========',
+    '\u2139 file | line % | branch % | funcs % | uncovered lines',
+    '\u2139 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',
+    '\u2139 test/fixtures/test-runner/invalid-tap.js | 100.00 | 100.00 | 100.00 | ',
+    '\u2139 test/fixtures/v8-coverage/throw.js | 71.43 | 50.00 | 100.00 | 5, 6',
+    '\u2139 all files | 78.35 | 43.75 | 60.00 |',
+    '\u2139 ===================================='
+  ].join('\n');
+
+  if (common.isWindows) {
+    return report.replaceAll('/', '\\');
+  }
+
+  return report;
+}
+
+test('coverage is reported and dumped to NODE_V8_COVERAGE if present', (t) => {
+  if (!process.features.inspector) {
+    return;
+  }
+
+  const fixture = fixtures.path('test-runner', 'coverage.js');
+  const args = ['--experimental-test-coverage', '--test-reporter', 'spec', fixture];
+  const options = { env: { ...process.env, NODE_V8_COVERAGE: tmpdir.path } };
+  const result = spawnSync(process.execPath, args, options);
+  const report = getCoverageFixtureReport();
+
+  assert(result.stdout.toString().includes(report));
+  assert.strictEqual(result.stderr.toString(), '');
+  assert.strictEqual(result.status, 0);
+  assert(findCoverageFileForPid(result.pid));
+});
+
+test('coverage is reported without NODE_V8_COVERAGE present', (t) => {
+  if (!process.features.inspector) {
+    return;
+  }
+
+  const fixture = fixtures.path('test-runner', 'coverage.js');
+  const args = ['--experimental-test-coverage', '--test-reporter', 'spec', fixture];
+  const result = spawnSync(process.execPath, args);
+  const report = getCoverageFixtureReport();
+
+  assert(result.stdout.toString().includes(report));
+  assert.strictEqual(result.stderr.toString(), '');
+  assert.strictEqual(result.status, 0);
+  assert(!findCoverageFileForPid(result.pid));
+});