From b23a410f68c7f86b746f191487e2f26966d0d2b9 Mon Sep 17 00:00:00 2001
From: Pietro Marchini <pietro.marchini94@gmail.com>
Date: Wed, 7 Aug 2024 23:20:56 +0200
Subject: [PATCH] test_runner: ensure test watcher picks up new test files

---
 lib/internal/test_runner/runner.js       | 19 ++++++++++--
 test/parallel/test-runner-run.mjs        |  3 ++
 test/parallel/test-runner-watch-mode.mjs | 39 ++++++++++++++++++++++--
 3 files changed, 57 insertions(+), 4 deletions(-)

diff --git a/lib/internal/test_runner/runner.js b/lib/internal/test_runner/runner.js
index a14cc97ce8690c..8e4c18fd726009 100644
--- a/lib/internal/test_runner/runner.js
+++ b/lib/internal/test_runner/runner.js
@@ -109,7 +109,7 @@ function createTestFileList(patterns) {
 
 function filterExecArgv(arg, i, arr) {
   return !ArrayPrototypeIncludes(kFilterArgs, arg) &&
-  !ArrayPrototypeSome(kFilterArgValues, (p) => arg === p || (i > 0 && arr[i - 1] === p) || StringPrototypeStartsWith(arg, `${p}=`));
+    !ArrayPrototypeSome(kFilterArgValues, (p) => arg === p || (i > 0 && arr[i - 1] === p) || StringPrototypeStartsWith(arg, `${p}=`));
 }
 
 function getRunArgs(path, { forceExit, inspectPort, testNamePatterns, testSkipPatterns, only }) {
@@ -166,7 +166,7 @@ class FileTest extends Test {
     if (firstSpaceIndex === -1) return false;
     const secondSpaceIndex = StringPrototypeIndexOf(comment, ' ', firstSpaceIndex + 1);
     return secondSpaceIndex === -1 &&
-          ArrayPrototypeIncludes(kDiagnosticsFilterArgs, StringPrototypeSlice(comment, 0, firstSpaceIndex));
+      ArrayPrototypeIncludes(kDiagnosticsFilterArgs, StringPrototypeSlice(comment, 0, firstSpaceIndex));
   }
   #handleReportItem(item) {
     const isTopLevel = item.data.nesting === 0;
@@ -416,7 +416,22 @@ function watchFiles(testFiles, opts) {
   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;
+  // Watch for created/deleted files in the current directory
+  const allFilesWatcher = new FilesWatcher({ __proto__: null, debounce: 200, mode: 'all', signal: opts.signal });
+  allFilesWatcher.watchPath(process.cwd());
+  allFilesWatcher.on('changed', ({ owners, eventType }) => {
+    if (eventType === 'rename') {
+      const updatedTestFiles = createTestFileList(opts.globPatterns);
+
+      const newFiles = ArrayPrototypeFilter(updatedTestFiles, (x) => !ArrayPrototypeIncludes(testFiles, x));
 
+      testFiles = updatedTestFiles;
+      newFiles.forEach((newFile) => {
+        watcher.emit('changed', { __proto__: null, owners: new SafeSet().add(newFile), eventType: 'rename' });
+      });
+    }
+  });
+  // Watch for changes in current filtered files
   watcher.on('changed', ({ owners, eventType }) => {
     if (!opts.hasFiles && eventType === 'rename') {
       const updatedTestFiles = createTestFileList(opts.globPatterns);
diff --git a/test/parallel/test-runner-run.mjs b/test/parallel/test-runner-run.mjs
index 7a575da9c95275..b718dab30b6305 100644
--- a/test/parallel/test-runner-run.mjs
+++ b/test/parallel/test-runner-run.mjs
@@ -4,6 +4,9 @@ import { join } from 'node:path';
 import { describe, it, run } from 'node:test';
 import { dot, spec, tap } from 'node:test/reporters';
 import assert from 'node:assert';
+import { EventEmitter } from 'events';
+
+EventEmitter.setMaxListeners(35);
 
 const testFixtures = fixtures.path('test-runner');
 
diff --git a/test/parallel/test-runner-watch-mode.mjs b/test/parallel/test-runner-watch-mode.mjs
index a55f404a4f7010..0ea8bfe19ae08a 100644
--- a/test/parallel/test-runner-watch-mode.mjs
+++ b/test/parallel/test-runner-watch-mode.mjs
@@ -34,12 +34,18 @@ function refresh() {
     .forEach(([file, content]) => writeFileSync(fixturePaths[file], content));
 }
 
-async function testWatch({ fileToUpdate, file, action = 'update' }) {
+async function testWatch({
+  fileToUpdate,
+  file,
+  action = 'update',
+  fileToCreate
+}) {
   const ran1 = util.createDeferredPromise();
   const ran2 = util.createDeferredPromise();
   const child = spawn(process.execPath,
                       ['--watch', '--test', file ? fixturePaths[file] : undefined].filter(Boolean),
-                      { encoding: 'utf8', stdio: 'pipe', cwd: tmpdir.path });
+                      { encoding: 'utf8', stdio: 'pipe', cwd: tmpdir.path }
+  );
   let stdout = '';
   let currentRun = '';
   const runs = [];
@@ -111,9 +117,34 @@ async function testWatch({ fileToUpdate, file, action = 'update' }) {
     }
   };
 
+  const testCreate = async () => {
+    await ran1.promise;
+    const newFilePath = tmpdir.resolve(fileToCreate);
+    const interval = setInterval(
+      () => writeFileSync(
+        newFilePath,
+        'module.exports = {};'
+      ),
+      common.platformTimeout(1000)
+    );
+    await ran2.promise;
+    runs.push(currentRun);
+    clearInterval(interval);
+    child.kill();
+    await once(child, 'exit');
+
+    for (const run of runs) {
+      assert.match(run, /# tests 1/);
+      assert.match(run, /# pass 1/);
+      assert.match(run, /# fail 0/);
+      assert.match(run, /# cancelled 0/);
+    }
+  };
+
   action === 'update' && await testUpdate();
   action === 'rename' && await testRename();
   action === 'delete' && await testDelete();
+  action === 'create' && await testCreate();
 }
 
 describe('test runner watch mode', () => {
@@ -141,4 +172,8 @@ describe('test runner watch mode', () => {
   it('should not throw when delete a watched test file', { skip: common.isAIX }, async () => {
     await testWatch({ fileToUpdate: 'test.js', action: 'delete' });
   });
+
+  it('should run new tests when a new file is created in the watched directory', async () => {
+    await testWatch({ action: 'create', fileToCreate: 'new-test-file.test.js' });
+  });
 });