test: increase coverage for events

1. test EventEmitter.setMaxListeners with invalid listener count
https://coverage.nodejs.org/coverage-0b6d3070a176d437/lib/events.js.html#L171

2. test EventEmitter.setMaxListeners with invalid emitter
https://coverage.nodejs.org/coverage-0b6d3070a176d437/lib/events.js.html#L186

3. test getEventListeners with invalid emiiter
Refs: https://coverage.nodejs.org/coverage-0b6d3070a176d437/lib/events.js.html#L706

4. test events.once with options: null
Refs: https://coverage.nodejs.org/coverage-0b6d3070a176d437/lib/events.js.html#L712

5. add test case for inspect new Event()
Refs: https://coverage.nodejs.org/coverage-0b6d3070a176d437/lib/internal/event_target.js.html#L111

6. add test case for insepct new EventTarget()
Refs: https://coverage.nodejs.org/coverage-0b6d3070a176d437/lib/internal/event_target.js.html#L446

7. add test case for Event and EventTarget constructor name

PR-URL: #36668
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

test/parallel/test-event-emitter-max-listeners.js

@@ -56,3 +56,17 @@ for (const obj of throwsObjs) {
 }
 
 e.emit('maxListeners');
+
+{
+  const { EventEmitter, defaultMaxListeners } = events;
+  for (const obj of throwsObjs) {
+    assert.throws(() => EventEmitter.setMaxListeners(obj), {
+      code: 'ERR_OUT_OF_RANGE',
+    });
+  }
+
+  assert.throws(
+    () => EventEmitter.setMaxListeners(defaultMaxListeners, 'INVALID_EMITTER'),
+    { code: 'ERR_INVALID_ARG_TYPE' }
+  );
+}

test/parallel/test-events-once.js

@@ -23,6 +23,18 @@ async function onceAnEvent() {
   strictEqual(ee.listenerCount('myevent'), 0);
 }
 
+async function onceAnEventWithNullOptions() {
+  const ee = new EventEmitter();
+
+  process.nextTick(() => {
+    ee.emit('myevent', 42);
+  });
+
+  const [value] = await once(ee, 'myevent', null);
+  strictEqual(value, 42);
+}
+
+
 async function onceAnEventWithTwoArgs() {
   const ee = new EventEmitter();
 
@@ -195,6 +207,7 @@ async function eventTargetAbortSignalAfterEvent() {
 
 Promise.all([
   onceAnEvent(),
+  onceAnEventWithNullOptions(),
   onceAnEventWithTwoArgs(),
   catchesErrors(),
   stopListeningAfterCatchingError(),

test/parallel/test-events-static-geteventlisteners.js

@@ -4,6 +4,7 @@ const common = require('../common');
 
 const {
   deepStrictEqual,
+  throws
 } = require('assert');
 
 const { getEventListeners, EventEmitter } = require('events');
@@ -34,3 +35,9 @@ const { getEventListeners, EventEmitter } = require('events');
   deepStrictEqual(getEventListeners(target, 'bar'), []);
   deepStrictEqual(getEventListeners(target, 'baz'), [fn1]);
 }
+
+{
+  throws(() => {
+    getEventListeners('INVALID_EMITTER');
+  }, /ERR_INVALID_ARG_TYPE/);
+}

test/parallel/test-eventtarget.js

@@ -13,7 +13,7 @@ const {
 
 const { once } = require('events');
 
-const { promisify } = require('util');
+const { promisify, inspect } = require('util');
 const delay = promisify(setTimeout);
 
 // The globals are defined.
@@ -541,3 +541,32 @@ let asyncTest = Promise.resolve();
   et.addEventListener('foo', listener);
   et.dispatchEvent(new Event('foo'));
 }
+
+{
+  const ev = new Event('test');
+  const evConstructorName = inspect(ev, {
+    depth: -1
+  });
+  strictEqual(evConstructorName, 'Event');
+
+  const inspectResult = inspect(ev, {
+    depth: 1
+  });
+  ok(inspectResult.includes('Event'));
+}
+
+{
+  const et = new EventTarget();
+  const inspectResult = inspect(et, {
+    depth: 1
+  });
+  ok(inspectResult.includes('EventTarget'));
+}
+
+{
+  const ev = new Event('test');
+  strictEqual(ev.constructor.name, 'Event');
+
+  const et = new EventTarget();
+  strictEqual(et.constructor.name, 'EventTarget');
+}