test_runner: add level-based diagnostic handling for reporter

lib/internal/test_runner/reporter/spec.js

@@ -69,8 +69,10 @@ class SpecReporter extends Transform {
       case 'test:stderr':
       case 'test:stdout':
         return data.message;
-      case 'test:diagnostic':
-        return `${reporterColorMap[type]}${indent(data.nesting)}${reporterUnicodeSymbolMap[type]}${data.message}${colors.white}\n`;
+      case 'test:diagnostic':{
+        const diagnosticColor = reporterColorMap[data.level] || reporterColorMap['test:diagnostic'];
+        return `${diagnosticColor}${indent(data.nesting)}${reporterUnicodeSymbolMap[type]}${data.message}${colors.white}\n`;
+      }
       case 'test:coverage':
         return getCoverageReport(indent(data.nesting), data.summary,
                                  reporterUnicodeSymbolMap['test:coverage'], colors.blue, true);

lib/internal/test_runner/reporter/utils.js

@@ -37,6 +37,15 @@ const reporterColorMap = {
   get 'test:diagnostic'() {
     return colors.blue;
   },
+  get 'info'() {
+    return colors.blue;
+  },
+  get 'warn'() {
+    return colors.yellow;
+  },
+  get 'error'() {
+    return colors.red;
+  },
 };
 
 function indent(nesting) {

lib/internal/test_runner/test.js

@@ -1087,7 +1087,7 @@ class Test extends AsyncResource {
           if (actual < threshold) {
             harness.success = false;
             process.exitCode = kGenericUserError;
-            reporter.diagnostic(nesting, loc, `Error: ${NumberPrototypeToFixed(actual, 2)}% ${name} coverage does not meet threshold of ${threshold}%.`);
+            reporter.diagnostic(nesting, loc, `Error: ${NumberPrototypeToFixed(actual, 2)}% ${name} coverage does not meet threshold of ${threshold}%.`, 'error');
           }
         }
 

lib/internal/test_runner/tests_stream.js

@@ -114,11 +114,12 @@ class TestsStream extends Readable {
     });
   }
 
-  diagnostic(nesting, loc, message) {
+  diagnostic(nesting, loc, message, level = 'info') {
     this[kEmitMessage]('test:diagnostic', {
       __proto__: null,
       nesting,
       message,
+      level,
       ...loc,
     });
   }