test_runner: emit diagnostics when watch mode drains

lib/internal/test_runner/harness.js

@@ -184,21 +184,26 @@ function setup(root) {
     __proto__: null,
     allowTestsToRun: false,
     bootstrapComplete: false,
+    watching: false,
     coverage: FunctionPrototypeBind(collectCoverage, null, root, coverage),
-    counters: {
-      __proto__: null,
-      all: 0,
-      failed: 0,
-      passed: 0,
-      cancelled: 0,
-      skipped: 0,
-      todo: 0,
-      topLevel: 0,
-      suites: 0,
+    resetCounters() {
+      root.harness.counters = {
+        __proto__: null,
+        all: 0,
+        failed: 0,
+        passed: 0,
+        cancelled: 0,
+        skipped: 0,
+        todo: 0,
+        topLevel: 0,
+        suites: 0,
+      };
     },
+    counters: null,
     shouldColorizeTestFiles: false,
     teardown: exitHandler,
   };
+  root.harness.resetCounters();
   root.startTime = hrtime();
   return root;
 }

lib/internal/test_runner/runner.js

@@ -36,6 +36,7 @@ const { createInterface } = require('readline');
 const { deserializeError } = require('internal/error_serdes');
 const { Buffer } = require('buffer');
 const { FilesWatcher } = require('internal/watch_mode/files_watcher');
+const { queueMicrotask } = require('internal/process/task_queues');
 const console = require('internal/console/global');
 const {
   codes: {
@@ -378,6 +379,7 @@ function runTestFile(path, filesWatcher, opts) {
       filesWatcher.runningSubtests.delete(path);
       if (filesWatcher.runningSubtests.size === 0) {
         opts.root.reporter[kEmitMessage]('test:watch:drained');
+        queueMicrotask(() => opts.root.postRun());
       }
     }
 
@@ -405,6 +407,7 @@ function watchFiles(testFiles, opts) {
   const runningSubtests = new SafeMap();
   const watcher = new FilesWatcher({ __proto__: null, debounce: 200, mode: 'filter', signal: opts.signal });
   const filesWatcher = { __proto__: null, watcher, runningProcesses, runningSubtests };
+  opts.root.harness.watching = true;
 
   watcher.on('changed', ({ owners }) => {
     watcher.unfilterFilesOwnedBy(owners);
@@ -431,7 +434,10 @@ function watchFiles(testFiles, opts) {
     kResistStopPropagation ??= require('internal/event_target').kResistStopPropagation;
     opts.signal.addEventListener(
       'abort',
-      () => opts.root.postRun(),
+      () => {
+        opts.root.harness.watching = false;
+        opts.root.postRun();
+      },
       { __proto__: null, once: true, [kResistStopPropagation]: true },
     );
   }

lib/internal/test_runner/test.js

@@ -847,7 +847,12 @@ class Test extends AsyncResource {
         reporter.coverage(nesting, loc, coverage);
       }
 
-      reporter.end();
+      if (harness.watching) {
+        this.reported = false;
+        harness.resetCounters();
+      } else {
+        reporter.end();
+      }
     }
   }
 

test/parallel/test-runner-run.mjs

@@ -195,9 +195,16 @@ describe('require(\'node:test\').run', { concurrency: true }, () => {
         signal: controller.signal,
       })
         .compose(async function* (source) {
+          let waitForCancel = 2;
           for await (const chunk of source) {
-            if (chunk.type === 'test:pass') {
+            if (chunk.type === 'test:watch:drained' ||
+                (chunk.type === 'test:diagnostic' && chunk.data.message.startsWith('duration_ms'))) {
+              waitForCancel--;
+            }
+            if (waitForCancel === 0) {
               controller.abort();
+            }
+            if (chunk.type === 'test:pass') {
               yield chunk.data.name;
             }
           }