Error in unit test vue.js karma: undefined is not a constructor ()

Question

This is my first unit test, and I am getting an error message that could not find why I am getting it on the forums so far.

This is my unit test:

import LoginPage from 'src/pages/Login'

describe('Login.vue', () => {
it('mounted is a fuction', () => {
    expect(typeof LoginPage.mounted).toBe('function')
})
})

And this is the login page:

<template>
<div class="">
    <p v-if="$route.query.redirect">
       You need to login first.
    </p>
    <form class="column is-one-third is-offset-one-third" @submit.prevent="login">
    <div class="control">
        <input type="email" placeholder="email" v-model="email" class="input">
    </div>
    <div class="control">
        <input type="password" autocomplete="off" placeholder="password" v-model="pass" class="input">
    </div>
    <div class="control">
        <button class="button is-primary" type="submit">Login</button>
        <a class="button" href="/signup">Sign up</button>
    </div>
    <p v-if="error" class="help is-danger">{{ error }}</p>
</form>
</div>
</template>
<script>
export default {
props: ['state'],
data () {
return {
    email: '',
    pass: '',
    error: ''
  }
},
mounted () {
if (this.state.auth.currentUser) {
    this.$router.replace(this.$route.query.redirect || '/')
}
},
methods: 
{
....//
}
}

, and this is the error message I get:

mounted is a fuction
Login.vue
undefined is not a constructor (evaluating 'expect((0, _typeof3.default)(_Login2.default.mounted)).toBe('function')')
webpack:///test/unit/specs/Component.spec.js:5:42 <- index.js:161:65

thank you for your help

Answer 1

There are two points here.

Firstly, you won’t get methods in the vue component in the same way, vue internally proxies methods, data, etc. so that they can be referenced via this, perhaps this led to your confusion.

Solution: componentName.methods.methodNamein your caseLoginPage.methods.mounted

:

import LoginPage from 'src/pages/Login'

describe('Login.vue', () => {
  it('mounted is a fuction', () => {
    expect(typeof LoginPage.methods.mounted).toBe('function')
  })
})