fix: properly hide relaySignal from process.listeners() (#741)

Author: Drarig29

src/preflight.cts

@@ -10,8 +10,10 @@ const bindHiddenSignalsHandler = (
 	handler: NodeJS.SignalsListener,
 ) => {
 	type RelaySignals = typeof signals[number];
+
+	const hiddenHandlers = new Map<RelaySignals, NodeJS.SignalsListener>();
 	for (const signal of signals) {
-		process.on(signal, (receivedSignal) => {
+		const hiddenHandler = (receivedSignal: NodeJS.Signals) => {
 			handler(receivedSignal);
 
 			/**
@@ -22,7 +24,10 @@ const bindHiddenSignalsHandler = (
 				// eslint-disable-next-line n/no-process-exit
 				process.exit(128 + osConstants.signals[signal]);
 			}
-		});
+		};
+
+		process.on(signal, hiddenHandler);
+		hiddenHandlers.set(signal, hiddenHandler);
 	}
 
 	/**
@@ -41,7 +46,9 @@ const bindHiddenSignalsHandler = (
 	process.listeners = function (eventName) {
 		const result: BaseEventListener[] = Reflect.apply(listeners, this, arguments);
 		if (signals.includes(eventName as RelaySignals)) {
-			return result.filter(listener => listener !== handler);
+			return result.filter(
+				listener => listener !== hiddenHandlers.get(eventName as RelaySignals),
+			);
 		}
 		return result;
 	};

tests/specs/cli.ts

@@ -178,6 +178,10 @@ export default testSuite(({ describe }, node: NodeApis) => {
 				});
 				setTimeout(() => {}, 1e5);
 				`,
+				'hidden-signals-handler.js': `
+				console.log('process.listeners().length = ' + process.listeners('SIGINT').length);
+				console.log('process.listenerCount() = ' + process.listenerCount('SIGINT'));
+				`,
 			});
 			onFinish(async () => await fixture.rm());
 
@@ -306,6 +310,17 @@ export default testSuite(({ describe }, node: NodeApis) => {
 				retry: 3,
 			});
 
+			test('Relay signal handlers are properly hidden', async () => {
+				const tsxProcess = tsx([
+					fixture.getPath('hidden-signals-handler.js'),
+				]);
+
+				const result = await tsxProcess;
+
+				expect(result.stdout).toBe('process.listeners().length = 0\nprocess.listenerCount() = 0');
+				expect(result.exitCode).toBe(0);
+			});
+
 			describe('Ctrl + C', ({ test }) => {
 				const CtrlC = '\u0003';