test_runner: print failed coverage reports with dot runner

When running tests with both the dot reporter and coverage reports,
if the coverage report fails there was no output (other than the dots)
but the program exits with a failure status code.

This change adds coverage failure output to the dot reporter, similar
to how the spec reporter handles coverage events. Now users can see
why the command failed without needing to check F12 console.

Fixes #60884

Signed-off-by: AZ & QZ <dev@local>

Author: AZ & QZ

lib/internal/test_runner/reporter/dot.js

@@ -4,12 +4,13 @@ const {
   MathMax,
 } = primordials;
 const colors = require('internal/util/colors');
-const { formatTestReport } = require('internal/test_runner/reporter/utils');
+const { formatTestReport, getCoverageReport } = require('internal/test_runner/reporter/utils');
 
 module.exports = async function* dot(source) {
   let count = 0;
   let columns = getLineLength();
   const failedTests = [];
+  const coverageFailures = [];
   for await (const { type, data } of source) {
     if (type === 'test:pass') {
       yield `${colors.green}.${colors.reset}`;
@@ -18,6 +19,16 @@ module.exports = async function* dot(source) {
       yield `${colors.red}X${colors.reset}`;
       ArrayPrototypePush(failedTests, data);
     }
+    if (type === 'test:coverage') {
+      // Check if coverage failed (threshold not met)
+      if (data.summary && (
+        (data.summary.lines && data.summary.lines.pct < 100) ||
+        (data.summary.functions && data.summary.functions.pct < 100) ||
+        (data.summary.branches && data.summary.branches.pct < 100)
+      )) {
+        ArrayPrototypePush(coverageFailures, data);
+      }
+    }
     if ((type === 'test:fail' || type === 'test:pass') && ++count === columns) {
       yield '\n';
 
@@ -33,6 +44,12 @@ module.exports = async function* dot(source) {
       yield formatTestReport('test:fail', test);
     }
   }
+  if (coverageFailures.length > 0) {
+    yield `\n${colors.red}Coverage report failed:${colors.white}\n\n`;
+    for (const coverage of coverageFailures) {
+      yield getCoverageReport('', coverage.summary, 'ℹ ', colors.blue, true);
+    }
+  }
 };
 
 function getLineLength() {