test: fix flaky test-watch-mode-kill-signal-*

test/fixtures/kill-signal-for-watch.js

@@ -1,4 +1,10 @@
-process.on('SIGTERM', () => { console.log('__SIGTERM received__'); process.exit(); });
-process.on('SIGINT', () => { console.log('__SIGINT received__'); process.exit(); });
-process.send('script ready');
+process.on('SIGTERM', () => {
+  console.log(`__SIGTERM received__ ${process.pid}`);
+  process.exit();
+});
+process.on('SIGINT', () => {
+  console.log(`__SIGINT received__ ${process.pid}`);
+  process.exit();
+});
+process.send(`script ready ${process.pid}`);
 setTimeout(() => {}, 100_000);

test/parallel/test-watch-mode-kill-signal-default.mjs

@@ -26,20 +26,37 @@ const child = spawn(
 );
 
 let stdout = '';
+let firstGrandchildPid;
 child.stdout.on('data', (data) => {
-  stdout += `${data}`;
-  if (/__(SIGINT|SIGTERM) received__/.test(stdout)) {
+  const dataStr = data.toString();
+  console.log(`[STDOUT] ${dataStr}`);
+  stdout += `${dataStr}`;
+  const match = dataStr.match(/__(SIGINT|SIGTERM) received__ (\d+)/);
+  if (match && match[2] === firstGrandchildPid) {
+    console.log(`[PARENT] Sending kill signal to watcher process: ${child.pid}`);
     child.kill();
   }
 });
 
+// After the write triggers a restart of the grandchild, the newly spawned second
+// grandchild can post another 'script ready' message before the stdout from the first
+// grandchild is relayed by the watcher and processed by this parent process to kill
+// the watcher. If we write again and trigger another restart, we can
+// end up in an infinite loop and never receive the stdout of the grandchildren in time.
+// Only write once to verify the first grandchild process receives the expected signal.
+// We don't care about the subsequent grandchild processes.
 child.on('message', (msg) => {
-  if (msg === 'script ready') {
-    writeFileSync(indexPath, indexContents);
+  console.log(`[MESSAGE]`, msg);
+  if (!firstGrandchildPid && typeof msg === 'string') {
+    const match = msg.match(/script ready (\d+)/);
+    if (match) {
+      firstGrandchildPid = match[1];  // This is the first grandchild
+      writeFileSync(indexPath, indexContents);
+    }
   }
 });
 
 await once(child, 'exit');
 
-assert.match(stdout, /__SIGTERM received__/);
-assert.doesNotMatch(stdout, /__SIGINT received__/);
+assert.match(stdout, new RegExp(`__SIGTERM received__ ${firstGrandchildPid}`));
+assert.doesNotMatch(stdout, new RegExp(`__SIGINT received__ ${firstGrandchildPid}`));

test/parallel/test-watch-mode-kill-signal-override.mjs

@@ -27,20 +27,40 @@ const child = spawn(
 );
 
 let stdout = '';
+let firstGrandchildPid;
 child.stdout.on('data', (data) => {
-  stdout += `${data}`;
-  if (/__(SIGINT|SIGTERM) received__/.test(stdout)) {
+  const dataStr = data.toString();
+  console.log(`[STDOUT] ${dataStr}`);
+  stdout += `${dataStr}`;
+  const match = dataStr.match(/__(SIGINT|SIGTERM) received__ (\d+)/);
+  if (match && match[2] === firstGrandchildPid) {
+    console.log(`[PARENT] Sending kill signal to watcher process: ${child.pid}`);
     child.kill();
   }
 });
 
+// After the write triggers a restart of the grandchild, the newly spawned second
+// grandchild can post another 'script ready' message before the stdout from the first
+// grandchild is relayed by the watcher and processed by this parent process to kill
+// the watcher. If we write again and trigger another restart, we can
+// end up in an infinite loop and never receive the stdout of the grandchildren in time.
+// Only write once to verify the first grandchild process receives the expected signal.
+// We don't care about the subsequent grandchild processes.
 child.on('message', (msg) => {
-  if (msg === 'script ready') {
-    writeFileSync(indexPath, indexContents);
+  console.log(`[MESSAGE]`, msg);
+  if (!firstGrandchildPid && typeof msg === 'string') {
+    const match = msg.match(/script ready (\d+)/);
+    if (match) {
+      firstGrandchildPid = match[1];  // This is the first grandchild
+      writeFileSync(indexPath, indexContents);
+    }
   }
 });
 
 await once(child, 'exit');
 
-assert.match(stdout, /__SIGINT received__/);
-assert.doesNotMatch(stdout, /__SIGTERM received__/);
+// The second grandchild, if there is one, could receive SIGTERM if it's killed as a
+// consequence of the parent being killed in this process instead of being killed by the
+// parent for file changes. Here we only care about the first grandchild.
+assert.match(stdout, new RegExp(`__SIGINT received__ ${firstGrandchildPid}`));
+assert.doesNotMatch(stdout, new RegExp(`__SIGTERM received__ ${firstGrandchildPid}`));