test_runner: print coverage and diagnostic info with dot reporter

lib/internal/test_runner/reporter/dot.js

@@ -4,12 +4,19 @@ const {
   MathMax,
 } = primordials;
 const colors = require('internal/util/colors');
-const { formatTestReport } = require('internal/test_runner/reporter/utils');
+const { getCoverageReport } = require('internal/test_runner/utils');
+const {
+  formatTestReport,
+  reporterColorMap,
+  reporterUnicodeSymbolMap,
+} = require('internal/test_runner/reporter/utils');
 
 module.exports = async function* dot(source) {
   let count = 0;
   let columns = getLineLength();
   const failedTests = [];
+  const diagnostics = [];
+  let coverage;
   for await (const { type, data } of source) {
     if (type === 'test:pass') {
       yield `${colors.green}.${colors.reset}`;
@@ -25,8 +32,24 @@ module.exports = async function* dot(source) {
       columns = getLineLength();
       count = 0;
     }
+    if (type === 'test:diagnostic' && data.level === 'error') {
+      ArrayPrototypePush(diagnostics, data);
+    }
+    if (type === 'test:coverage') {
+      coverage = data;
+    }
   }
   yield '\n';
+  if (diagnostics.length > 0) {
+    for (const diagnostic of diagnostics) {
+      const color = reporterColorMap[diagnostic.level] || reporterColorMap['test:diagnostic'];
+      yield `${color}${reporterUnicodeSymbolMap['test:diagnostic']}${diagnostic.message}${colors.white}\n`;
+    }
+    if (coverage) {
+      yield getCoverageReport('', coverage.summary,
+                              reporterUnicodeSymbolMap['test:coverage'], colors.blue, true);
+    }
+  }
   if (failedTests.length > 0) {
     yield `\n${colors.red}Failed tests:${colors.white}\n\n`;
     for (const test of failedTests) {

test/fixtures/test-runner/output/dot_reporter_coverage_threshold.js

@@ -0,0 +1,17 @@
+'use strict';
+require('../../../common');
+const fixtures = require('../../../common/fixtures');
+const spawn = require('node:child_process').spawn;
+
+spawn(
+  process.execPath,
+  [
+    '--no-warnings',
+    '--experimental-test-coverage',
+    '--test-coverage-exclude=!test/**',
+    '--test-coverage-lines=99',
+    '--test-reporter', 'dot',
+    fixtures.path('test-runner/coverage.js'),
+  ],
+  { stdio: 'inherit' },
+);

test/fixtures/test-runner/output/dot_reporter_coverage_threshold.snapshot

@@ -0,0 +1,18 @@
+invalid tap output
+.
+ℹ Error: 78.35% line coverage does not meet threshold of 99%.
+ℹ start of coverage report
+ℹ --------------------------------------------------------------------------------------------
+ℹ file              | line % | branch % | funcs % | uncovered lines
+ℹ --------------------------------------------------------------------------------------------
+ℹ test              |        |          |         | 
+ℹ  fixtures         |        |          |         | 
+ℹ   test-runner     |        |          |         | 
+ℹ    coverage.js    |  78.65 |    38.46 |   60.00 | 12-13 16-22 27 39 43-44 61-62 66-67 71-72
+ℹ    invalid-tap.js | 100.00 |   100.00 |  100.00 | 
+ℹ   v8-coverage     |        |          |         | 
+ℹ    throw.js       |  71.43 |    50.00 |  100.00 | 5-6
+ℹ --------------------------------------------------------------------------------------------
+ℹ all files         |  78.35 |    43.75 |   60.00 | 
+ℹ --------------------------------------------------------------------------------------------
+ℹ end of coverage report

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

@@ -170,4 +170,25 @@ for (const coverage of coverages) {
     assert.strictEqual(result.status, 1);
     assert(!findCoverageFileForPid(result.pid));
   });
+
+  test(`test failing ${coverage.flag} with dot reporter`, () => {
+    const result = spawnSync(process.execPath, [
+      '--test',
+      '--experimental-test-coverage',
+      '--test-coverage-exclude=!test/**',
+      `${coverage.flag}=99`,
+      '--test-reporter', 'dot',
+      fixture,
+    ]);
+
+    const stdout = result.stdout.toString();
+    assert.match(
+      stdout,
+      RegExp(`Error: ${coverage.actual.toFixed(2)}% ${coverage.name} coverage does not meet threshold of 99%`)
+    );
+    assert.match(stdout, /start of coverage report/);
+    assert.match(stdout, /end of coverage report/);
+    assert.strictEqual(result.status, 1);
+    assert(!findCoverageFileForPid(result.pid));
+  });
 }

test/test-runner/test-output-dot-reporter-coverage-threshold.mjs

@@ -0,0 +1,15 @@
+// Test that the output of test-runner/output/dot_reporter_coverage_threshold.js matches
+// test-runner/output/dot_reporter_coverage_threshold.snapshot
+import * as common from '../common/index.mjs';
+import * as fixtures from '../common/fixtures.mjs';
+import { spawnAndAssert, specTransform, ensureCwdIsProjectRoot } from '../common/assertSnapshot.js';
+
+if (!process.features.inspector) {
+  common.skip('inspector support required');
+}
+
+ensureCwdIsProjectRoot();
+await spawnAndAssert(
+  fixtures.path('test-runner/output/dot_reporter_coverage_threshold.js'),
+  specTransform,
+);