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Cute jest matchers to test Vue components with vue-test-utils

Cute jest matchers to test Vue components with vue-test-utils

jest-matcher-vue-test-utils

Cute matchers for Jest to test Vue components with Vue Test Utils.

You can write tests for Vue component/store intuitively ⚡️

it("Emits 'select' event by clicking PrimaryButton", () => {
  const wrapper = shallowMount(Component);
  
  expect(wrapper.emitted().select).toBeUndefined();
  wrapper.find(PrimaryButton).vm.$emit("click");
  expect(wrapper.emitted().select[0]).toBeTruthy();
});

becomes

it("Emits 'select' event by clicking PrimaryButton", () => {
  const wrapper = shallowMount(Component);
  
  expect(() => {
    wrapper.find(PrimaryButton).vm.$emit("click");
  }).toEmit(wrapper, "select");
});

And all matchers have type definition and doc 💇‍♂️

jest-matcher-vue-test-utils

Installation

Get from npm:

$ npm install -D jest-matcher-vue-test-utils

Then, register matchers on your jest process:

import vueTestUtilMatchers from "jest-matcher-vue-test-utils";
expect.extend({ ...vueTestUtilMatchers });

Provided Matchers

Existence on Wrapper

toShow

Assert the function shows a content on Wrapper of vue-test-utils
// error-message.vue
<template>
  <div>
    <p v-if="isError" class="error">message</p>
  </div>
</template>

...

data: function () {
  return {
    isError: false
  }
},
methods: {
  showError () {
    this.isError = true;
  }
}
import Component from "./error-message.vue";

it("show error by showError", async () => {
  return expect(async () => {
    wrapper.vm.showError();
    await wrapper.vm.$nextTick();
  }).toShow(wrapper, "p.error"); // Passes
});

toHide

Assert the function hides a content on Wrapper of vue-test-utils
// error-message.vue
<template>
  <div>
    <p v-if="isError" class="error">message</p>
  </div>
</template>

...

data: function () {
  return {
    isError: true
  }
},
methods: {
  hideError () {
    this.isError = false;
  }
}
import Component from "./error-message.vue";

it("show error by showError", async () => {
  return expect(async () => {
    wrapper.vm.hideError();
    await wrapper.vm.$nextTick();
  }).toHide(wrapper, "p.error"); // Passes
});

Events on Wrapper

toEmit

Assert the action emits the event (with the payload optionally) on Wrapper of vue-test-utils
// event.vue
<template>
  <div @click="emitEvent('clicked')">
    Click Me
  </div>
</template>

<script>
module.exports = {
  methods: {
    emitEvent (e) {
      this.$emit("special", e);
    }
  }
}
</script>
import Component from "./event.vue";

it("emits special event by click", () => {
  const wrapper = shallowMount(Component);
  expect(() => wrapper.trigger("click")).toEmit(wrapper, "special"); // Passes
  expect(() => wrapper.trigger("click")).toEmit(wrapper, "special", "clicked"); // Passes
});

Async function is supported as well.

it("emits special event by click", async () => {
  const wrapper = shallowMount(Component);
  return expect(async () => triggersEventAsynchronously()).toEmit(wrapper, "special", "clicked"); // Passes
});

toHaveEmitted

Assert the event is emitted (with the payload optionally) on Wrapper of vue-test-utils
// event.vue
<template>
  <div @click="emitEvent('clicked')">
    Click Me
  </div>
</template>

<script>
module.exports = {
  methods: {
    emitEvent (e) {
      this.$emit("special", e);
    }
  }
}
</script>
import Component from "./event.vue";

it("emits special event by click", () => {
  const wrapper = shallowMount(Component);
  wrapper.trigger("click");
  expect(wrapper).toHaveEmitted("special"); // Passes
  expect(wrapper).toHaveEmitted("special", "clicked"); // Passes
});

Vuex actions/mutations

toDispatch

Assert the function dispatches Vuex action on the component
// click-store.vue
<template>
  <div @click="dispatchStore('click')">
    Click Me
  </div>
</template>

<script>
module.exports = {
  methods: {
    dispatchStore (e) {
      this.$store.dispatch('awesomeAction', e);
    }
  }
}
</script>
import Component from "./click-store.vue";

it("Dispatches the action on store by click", () => {
  const wrapper = shallowMount(Component);
  expect(() => {
    wrapper.trigger("click");
  }).toDispatch(wrapper, "awesomeAction"); // Passes

  expect(() => {
    wrapper.trigger("click");
  }).toDispatch(wrapper, "awesomeAction", 'click'); // Passes
});

Async function is supported as well.

it("dispatches the action on store by click", async () => {
  return expect(async () => {
    dispatchEventAsynchronosly();
  }).toDispatch(wrapper, "awesomeAction", 'click'); // Passes
});

toCommit (TBD)

Assert the store mutation is committed
// click-store.vue
<template>
  <div @click="commitStore('click')">
    Click Me
  </div>
</template>

<script>
module.exports = {
  methods: {
    commitStore (e) {
      this.$store.commit('importantMutation', e);
    }
  }
}
</script>
import Component from "./click-store.vue";

it("Commits the mutation on store by click", () => {
  const wrapper = shallowMount(Component);
  expect(() => {
    wrapper.trigger("click");
  }).toCommit(wrapper, "importantMutation"); // Passes

  expect(() => {
    wrapper.trigger("click");
  }).toCommit(wrapper, "importantMutation", 'click'); // Passes
});

toHaveDispatched

Assert a component has dispatched Vuex action
// click-store.vue
<template>
  <div @click="dispatchStore('click')">
    Click Me
  </div>
</template>

<script>
module.exports = {
  methods: {
    dispatchStore (e) {
      this.$store.dispatch('awesomeAction', e);
    }
  }
}
</script>
import Component from "./click-store.vue";
import { vuexPlugin } from "jest-matcher-vue-test-utils";

it("Dispatches the action on store by click", () => {
  const store = new Vuex.Store({
    actions: dispatchStore() {},
    plugins: [vuexPlugin()] // Requires adding plugin to use `toHaveDispatched` matcher
  });

  const wrapper = shallowMount(Component, { store })
  wrapper.trigger("click");
  expect(wrapper).toHaveDispatched("awesomeAction"); // Passes
  expect(wrapper).toHaveDispatched("awesomeAction", "click"); // Passes
});

Prop Validations

toBeValidProps

Assert that a prop set is valid for a component
// name-require-and-fullname-is-validated-component.vue
props: {
  name: {
    type: String,
    required: true
  }
  fullname: {
    validator: function (val) {
      return !!val && val.match(/.+\s.+/);
    }
  }
}
import Component from "./name-require-and-fullname-is-validated-component.vue";

it("component validates props", () => {
  expect(Component).toBeValidProps({ name: "required name", fullName: "Kengo Hamasaki" }); // Passes
  expect(Component).toBeValidProps({ fullName: "Kengo Hamasaki" }); // Fails
  expect(Component).toBeValidProps({ name: "required name", fullName: "Kengo" }); // Fails
});

toBeValidProp

Assert that a single prop is valid for a component
// name-require-component.vue
props: {
  name: {
    type: String,
    required: true
  }
}
import Component from "./name-require-component.vue";

it("component validates props", () => {
  expect(Component).toBeValidProp("name", "Required Name"); // Passes
  expect(Component).toBeValidProp("name", null); // Fails as required
  expect(Component).toBeValidProp("name", 123}); // Fails as typecheck
});

toRequireProp

Assert that a component requires a prop
// name-require-component.vue
props: {
  name: {
    type: String,
    required: true
  }
}
import Component from "./name-require-component.vue";

it("component requires name prop", () => {
  expect(Component).toRequireProp("name"); // Passes
  expect(Component).toRequireProp("birthday"); // Fails
});

toHaveDefaultProp

Assert that a component gives default to a prop
// default-address-component.vue
props: {
  address: {
    type: String,
    default: "Kitakyushu, Japan"
  }
}
import Component from "./default-address-component.vue";

it("component gives default value for address prop", () => {
  expect(Component).toHaveDefaultProp("address", "Kitakyushu, Japan"); // Passes
  expect(Component).toHaveDefaultProp("address", "San Francisco, US"); // Fails
});

toBeValidPropWithTypeCheck

Assert that a component validates a prop with type
// takes-zipcode-component.vue
props: {
  zipcode: {
    type: String
  }
}
import Component from "./takes-zipcode-component.vue";

it("component validates zipcode prop", () => {
  expect(Component).toBeValidPropWithTypeCheck("zipcode", "94103"); // Passes
  expect(Component).toBeValidPropWithTypeCheck("zipcode", 94103); // Fails
});

toBeValidPropWithCustomValidator

Assert that a component validates a prop with custom validator
// fullname-is-validated-component.vue
props: {
  fullname: {
    validator: function (val) {
      return !!val && val.match(/.+\s.+/);
    }
  }
}
import Component from "./fullname-is-validated-component.vue";

it("component validates fullname prop", () => {
  expect(Component).toBeValidPropWithCustomValidator("fullname", "Kengo Hamasaki"); // Passes
  expect(Component).toBeValidPropWithCustomValidator("fullname", "Kengo"); // Fails
});

Config

We can configure the matchers. Currently accepting mountOptions property to give options for shallowMount which is running in inside of matchers.

import vueTestUtilMatchers, { config } from "jest-matcher-vue-test-utils";
import { createLocalVue } from "@vue/test-utils";

config({
  mountOptions: { localVue: createLocalVue() }
});

GitHub

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