[Vue warn]: Unknown custom element: <nuxt-link> - When running jest unit tests

Although the answers provided could work. What I ended up using was based on this guide

const wrapper = mount(TestItem, {
  propsData: { item },
  localVue,
  store,
  stubs: {
    NuxtLink: true,
    // Any other component that you want stubbed
  },
});

This is how I was able to get rid of the annoying warning:

Include RouterLinkStub, eg.:

import { shallowMount, createLocalVue, RouterLinkStub } from '@vue/test-utils';

Map NuxtLink stub to RouterLinkStub

const wrapper = shallowMount(TestItem, {
  ...
  stubs: {
    NuxtLink: RouterLinkStub
  }
})

And in case you were checking nuxt-link text or something, change:

const link = wrapper.find('nuxt-link');

to

const link = wrapper.find(RouterLinkStub);

Found this gold on https://onigra.github.io/blog/2018/03/19/vue-test-utils-router-link-stub/

Good thing you don't need to know japanese to read code...