How can i know if Parent component pass a function to Child component

[Watanuki12138]

Parent1.vue pass 'test' function do something
Parent2.vue dont pass 'test' function then do something else

Parent1.vue

<template>
<Child @test='testParent '></Child>
</template>
<script>
import { defineComponent } from 'vue';
import Child from './Child.vue';
export default defineComponent({
components: {Child},
setup(){
const testParent = () =>{
     console.log('test')
}
return{
  testParent,
}
}
});
</script>

Parent2.vue

<template>
     <Child></Child>
</template>
<script>
import { defineComponent } from 'vue';
import Child from './Child.vue';
export default defineComponent({
components: {Child},
});
</script>

Child.vue

<script>
import { defineComponent } from 'vue';
export default defineComponent({
emits:['test'],
setup(){
const testChild = () =>{
     // I want to know how to write check condition next line
     if(Parent pass 'test' function){
         context.emit('test');
     }else{
        console.log('no test');
     }
}
return{
testChild,
}
}
});
</script>

Excepted console result:
Parent1.vue

test

Parent2.vue

no test

[edison1105]

use context.attrs. see demo

[LinusBorg]

That would also add this as a listener to the root element which I would say is usually nto a real problem (but can be if you pick an existing DOM event name) yet should be avoided.

Better: define it as a prop instead:

https://sfc.vuejs.org/#__DEV__eNp9UstOwzAQ/JXFl6RSa4trlVQgLnwAEgfMIbSbksov2U6pFOXfWTtNqQD1Yntn1uOdXQ/s0Tl+7JGtWRW2vnMRAsbebaTptLM+wgAeWxih9VZDQanFhXqy2p1xLlKQlIjeWhMi6LCHOl0ui2dUysKr9Wp3VyzmhIi01FAu6s0wSlOJqQB6moKI2qkmIkUA1ef9Zhiy4jhWgiJCZazSm+LqDA9Js5YsbZIlqhIXJbZkU+Er3Th+CNaQ6yHpyzMRJFtDRhJGZlIs2WeMLqyFCO02OTwEbv1e0In73sROI8egVx/efgX0JCzZ8kpDEHhEv/JodujR39L8lfpHN8lSq0ayMvf7Z3K3ZyYNnjK5w7bpVcw2nbdUBbwV1rxQy4r3XHj+AWXmlkCziniKi3NbunYi+HRjhiHlBauQK7svo++RxpzgEVXAf5Pahpg5azZ24xtcT3L8Bjga8Go=

[Watanuki12138]

Thanks! Your answer solved my problem!