test: improve coverage of lib/events.js

test/parallel/test-event-emitter-emit-context.js

@@ -0,0 +1,18 @@
+'use strict';
+constcommon=require('../common');
+constassert=require('assert');
+constEventEmitter=require('events');
+
+// Test emit called by other context
+constEE=newEventEmitter();
+
+// Works as expected if the context has no `constructor.name`
+{
+constctx=Object.create(null);
+assert.throws(
+()=>EE.emit.call(ctx,'error',newError('foo')),
+common.expectsError({name: 'Error',message: 'foo'})
+);
+}
+
+assert.strictEqual(EE.emit.call({},'foo'),false);

test/parallel/test-event-on-async-iterator.js → test/parallel/test-events-on-async-iterator.js

@@ -35,6 +35,13 @@ async function basic(){
  assert.strictEqual(ee.listenerCount('error'), 0);
 }
 
+async function invalidArgType(){
+ assert.throws(() => on({}, 'foo'), common.expectsError({
+ code: 'ERR_INVALID_ARG_TYPE',
+ name: 'TypeError',
+ }));
+}
+
 async function error(){
  const ee = new EventEmitter();
  const _err = new Error('kaboom');
@@ -359,6 +366,7 @@ async function abortableOnAfterDone(){
 async function run(){
  const funcs = [
  basic,
+ invalidArgType,
  error,
  errorDelayed,
  throwInLoop,