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Mixing Storybook with Angular with a Sprinkle of Applitools


To better understand the Applitools Storybook SDK for Angular, we will be building a small Angular application from scratch, adding some Storybook stories, and then finally performing visual regression testing using the Applitools SDK to generate snapshots for us to view and analyze.

You can find the source code for this article on GitHub by following this link storybook-angular-applitools repo.

Create Angular 7 App using the latest CLI

Make sure you have the latest Angular CLI installed. In my case, I will be using the Angular CLI v7.0.2. Create a new Angular App using the following npm command:

ng new storybook-angular-applitools

Create the ContentEditable Component

The ContentEditable component we are going to build in this section wraps an HTML <div> element and adds an HTML attribute of contenteditable=”true”. The component implements the ControlValueAccessor so that the component can be used like any other Angular form control inside HTML forms.

<div contenteditable=”true”>This is an editable paragraph.</div>

The HTML fragment above renders in the browser as an editable area that users can click and enter any text or HTML.

Create a new component file and add the following markup to contenteditable.component.html file:


Next, add the code below to the contenteditable.component.ts file:

import { Component, ChangeDetectionStrategy, Input, forwardRef, OnChanges, SimpleChanges, ElementRef, Renderer2, ViewChild } from '@angular/core';
import { ControlValueAccessor, NG_VALUE_ACCESSOR } from '@angular/forms';

  // tslint:disable-next-line:component-selector
  selector: 'editable',
  templateUrl: `./contenteditable.component.html`,
  styles: [],
  changeDetection: ChangeDetectionStrategy.OnPush,
  providers: [
      provide: NG_VALUE_ACCESSOR,
      useExisting: forwardRef(() => ContentEditableComponent),
      multi: true

export class ContentEditableComponent
  implements ControlValueAccessor, OnChanges {
  @ViewChild('container') container;
  private _styles: any;
  private _contentValue: any;

  propagateChange: (value: any) => void = () => {};

  set styles(style: any) {
    this._styles = style;

  get styles(): any {
    return this._styles;

  get contentValue(): any {
    return this._contentValue;

  set contentValue(val: any) {
    if (this._contentValue !== val) {
      this._contentValue = val;

  writeValue(value: any) {
    if (value !== this._contentValue) {
      this.contentValue = value;

  registerOnChange(fn: (value: any) => void) {
    this.propagateChange = fn;

  registerOnTouched(fn: () => void) {}

  setContent($event: any): void {
    // this._contentValue = $;

  ngOnChanges(changes: SimpleChanges): void {}

The component is straightforward and follows the best practices in building a ControlValueAccessor. It defines a single @Input() property to allow the consumer of this component to control its styling.

If you want to fully understand how ControlValueAccessor works in Angular check out Max’s article titled Never again be confused when implementing ControlValueAccessor in Angular.

Next, add the following HTML snippet to the app.component.html file:

<section class="section">
 <h2>Two-way Data-binding</h2>
 <editable name="editable2" [styles]="styles()" [(ngModel)]="content1"></editable>
 <pre>{ content1 | json }</pre>

Define the styles() method inside the AppComponent class:

styles() {
 return {
  "background-color": "yellow",
   margin: "10px auto",
  "max-width": "60%",
  "line-height": "25px",
  padding: "10px"

And now run the application. You should see something similar to this below.

ContentEditableComponent in action

You can start typing in the yellow editable rectangle and you will see whatever you type underneath.

Let’s switch gears and add Storybook to the application.

Add Storybook packages

We need to add Storybook for Angular to your application. The Storybook website offers a detailed installation guide on Storybook for Angular. Once installed, apply the following changes, so that Storybook runs correctly with your Angular 7 application.

Open the src/app/ file and make sure the exclude property has the following values:

"exclude": [

Open the .storybook/tsconfig.json file and paste the following:

 "extends": "../src/",
 "compilerOptions": {
    "types": [
 "exclude": [
 "include": [

Create and run a few Storybook stories

Add the following Storybook stories into the file located at src/app/stories/index.stories.ts:

storiesOf('ContentEditable Component', module)
   'with yellow background',
   withNotes('Testing the background color for the editable area and setting it to yellow')(() => ({
     component: ContentEditableComponent,
     props: {
       styles: { 'background-color': 'yellow', 'padding': '20px' },
       ngModel: 'The content goes here',
       ngModelChange: action('ngModelChange')
   'with red background',
   withNotes('Testing the background color for the editable area by setting it to red')(() => ({
     component: ContentEditableComponent,
     props: {
       styles: { 'background-color': 'red', 'color': '#fff', 'padding': '20px' },
       ngModel: 'The content goes here',
       ngModelChange: action('ngModelChange')

The first story renders the ContentEditable component with a yellow background. While the second renders the component with a red background.

Run the Storybook tool to view and test your stories by issuing the following CLI command:

npm run storybook

You should be able to see something similar to this:

ContentEditableComponent under Storybook IDE

Now that we are sure the Storybook stories are up and running, let’s set up Applitools to use these stories and run our visual automated tests.

Add and run Applitools Storybook SDK for Angular

To add Applitools Storybook SDK for Angular to this application issue the following CLI command:

npm install @applitools/eyes.storybook --save-dev

Make sure to grab an Applitool API Key and store it on your machine. For a complete tutorial on how to install and run Applitools Storybook SDK for Angular, you may check this link: Storybook Angular Tutorial.

To run the Storybook stories and send the snapshots to the Applitools Server, issue the following command:

npx [eyes-storybook](

The command simply opens the Storybook stories, runs them one by one, and then sends all the DOM snapshots to the Applitools Server. Let’s have a look at the test results inside Applitools Test Manager.

Review test results on Applitools Test Manager

We can see the results of the tests we just ran from the Applitools Test Manager. To access the Applitools Test Manager, navigate to Sign in to get onto the Dashboard. For a detailed look at the Applitools Test Manager, you can check my article on Applitools — The automated visual regression testing framework

The results for running the Storybook tests show the following:

Applitools Test Manager Results

The test manager lists the test runs or batches (as referred to by Applitools) on the left- hand side. Clicking on any of the batches displays all of the snapshots for all of the Storybook stories in your application.

Click on the first snapshot (the red color) to expand and review it in detail:

Inspecting results with Test Manager

A rich toolbox is available to zoom in/out on the snapshot and compare this snapshot to any previously taken, known as the baseline. In this case, since this is the first time we are running the stories, there won’t be any baseline set. Therefore, Applitools Test Manager sets these snapshots as a baseline for upcoming regression test cycles.

Next, we’re going to simulate what happens when we have a visual regression in one of our components. To do this most easily, we’ll change one of our Storybook stories to render our component in a way that will be different from the baseline images we took earlier. Then, when we re-run the visual testing, we should see a discrepancy appear that we’ll have to resolve.

To do this, let’s assume that the story named in the red background above, has the ngModel value changed and now reads as follows:

  'with red background',
  withNotes('Testing the background color for the editable area by setting it to red')(() => ({
    component: ContentEditableComponent,
    props: {
      styles: { 'background-color': 'red', 'color': '#fff', 'padding': '20px' },
      ngModel: 'The red content goes here',
      ngModelChange: action('ngModelChange')

Now run this command:

npx eyes-storybook

The command gives you a detailed test result every time you run it. Check the following results:

Using @applitools/eyes.storybook version 2.1.9.

√ Storybook was started
√ Reading stories
√ Done 2 stories out of 2


ContentEditable Component: with yellow background [1024x768] — Passed

ContentEditable Component: with red background [1024x768] — Failed 1 of 1

A total of 1 difference was found.

See details at [](

Total time: 36 seconds

Running the second story fails, as expected because we changed the content that was initially displayed inside the ContentEditable component. The test result output provides you with a link to check the discrepancies online. Click on the link to open the issues directly in the Applitools Test Manager:

Showing differences on the Test Manager

A new batch is displayed on the left-hand side with a status of Unresolved. The Unresolved status indicates that the Applitools Test Manager discovered a discrepancy between the two test runs. This will require your input in order to resolve the discrepancy. Either approve the difference, and create a new baseline, or reject it to keep the original baseline.

Notice the blue square above indicating the Not Equal sign. This means the second snapshot test run has some differences to the first test run snapshot (the baseline). Clicking on the first snapshot reveals the differences between both snapshots. The current one and the baseline. The differences in content are highlighted in blue. You can also compare the new snapshot with the baseline by selecting both:

Compare two snapshots side by side

This should display both side by side and all differences are highlighted for you. You may spend more time at the Applitools Test Manager to explore all the rich features provided for you to do a thorough analysis on running the story tests.


This article touched the surface on how you can mix together Storybook and Angular together in one application. By means of Applitools Storybook SDK for Angular, you can provide automated visual UI testing by running the Storybook stories and generate snapshots that are then sent to the Applitools AI Server to compare and analyze and prepare the test results for you.

You can grab the code for this article by cloning the repository on GitHub.

This Dot Labs is a development consultancy that is trusted by top industry companies, including Stripe, Xero, Wikimedia, Docusign, and Twilio. This Dot takes a hands-on approach by providing tailored development strategies to help you approach your most pressing challenges with clarity and confidence. Whether it's bridging the gap between business and technology or modernizing legacy systems, you’ll find a breadth of experience and knowledge you need. Check out how This Dot Labs can empower your tech journey.

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By introducing createApp(), you can instantiate multiple Vue apps side by side. It creates a context or boundary for your app instance where you do all the registration as you will see shortly. Typically, a Vue app is started inside the main.js` file. Let’s visit this file and make the necessary changes to upgrade to Vue 3. `javascript import Vue from "vue"; import App from "./App.vue"; import GlobalVarMixin from "./mixins/global-variables-mixin"; import router from "./router"; import VueAnalytics from "vue-analytics"; //layouts import Default from "./1.layouts/l-default.vue"; import Form from "./1.layouts/l-form.vue"; import Content from "./1.layouts/l-content.vue"; Vue.component("l-default", Default); Vue.component("l-form", Form); Vue.component("l-content", Content); Vue.mixin(GlobalVarMixin); if (process.env.VUEAPP_GOOGLE_ANALYTICS_ID) { Vue.use(VueAnalytics, { id: process.env.VUEAPP_GOOGLE_ANALYTICS_ID, router }); } else { console.log("Google Analytics not loaded"); } Vue.config.productionTip = false; new Vue({ router, render: h => h(App) }).$mount("#app"); ` This is a slimmed down version of the original main.js` file in the app. Let’s dissect the file one line at a time and upgrade accordingly. `javascript import Vue from "vue"; ` Replace the line above with: `javascript import { createApp } from "vue"; ` Let’s replace the code that’s creating the app using the Vue 3 createApp() function. `javascript new Vue({ router, render: h => h(App) }).$mount("#app"); ` Replace with: `javascript const app = createApp(App); ` The app` variable now holds a new Vue app instance for us. The `router` instance will be registered separately. Let’s update the Vue component registration. `javascript Vue.component("l-default", Default); Vue.component("l-form", Form); Vue.component("l-content", Content); ` Replace with: `javascript app.component("l-default", Default); app.component("l-form", Form); app.component("l-content", Content); ` With Vue 3, you register components at the app instance level and not globally. Let’s update the Vue mixin registration. `javascript Vue.mixin(GlobalVarMixin); ` Replace with: `javascript app.mixin(GlobalVarMixin); ` Now register the router` on the app instance as follows: `javascript app.use(router); ` Now let’s register the vue-analytics plugin on the app instance. `javascript if (process.env.VUEAPP_GOOGLE_ANALYTICS_ID) { Vue.use(VueAnalytics, { id: process.env.VUEAPP_GOOGLE_ANALYTICS_ID, router }); } else { console.log("Google Analytics not loaded"); } ` Replace with: `javascript if (process.env.VUEAPP_GOOGLE_ANALYTICS_ID) { app.use(VueAnalytics, { id: process.env.VUEAPP_GOOGLE_ANALYTICS_ID, router }); } else { console.log("Google Analytics not loaded"); } ` The plugin is now installed on the app instance rather than the global Vue instance. This is also valid for any other plugin out there. Make sure to remove the line below as it’s not needed anymore in Vue 3 apps: `javascript Vue.config.productionTip = false; ` Finally, let’s mount the app instance by using the following: `javascript app.mount("#app"); ` The final version of the upgrade main.js` file looks like this: `javascript import { createApp } from "vue"; import App from "./App.vue"; import router from "./router"; import GlobalVarMixin from "./mixins/global-variables-mixin"; import VueAnalytics from "vue-analytics"; //layouts import Default from "./1.layouts/l-default.vue"; import Form from "./1.layouts/l-form.vue"; import Content from "./1.layouts/l-content.vue"; const app = createApp(App); app.component("l-default", Default); app.component("l-form", Form); app.component("l-content", Content); app.mixin(GlobalVarMixin); app.use(router); if (process.env.VUEAPP_GOOGLE_ANALYTICS_ID) { app.use(VueAnalytics, { id: process.env.VUEAPP_GOOGLE_ANALYTICS_ID, router }); } else { console.log("Google Analytics not loaded"); } app.mount("#app"); ` That’s it! Step 6: Upgrade the `router.js` file The Vue Router has undergone changes and it’s now under v4.0. Let’s review what the current router.js` file looks like: `javascript import Vue from "vue"; import Router from "vue-router"; Vue.use(Router); export default new Router({ routes: [ ... ], scrollBehavior(to, from, savedPosition) { if (to.hash) { return { selector: to.hash }; } else if (savedPosition) { return savedPosition; } else { return { x: 0, y: 0 }; } } }); ` Replace the import statements with the following line: `javascript import { createRouter, createWebHashHistory } from "vue-router"; ` Instead of creating a new instance of the Router` object, we will be using the new function provided by Vue Router which is `createRouter()`. `javascript export default createRouter({ history: createWebHashHistory(), routes: [...] }) ` The router.js` file now exports an instance of the `Router` object using the `createRoute()` function. This function expects an input parameter of type object. The `routes` and `history` properties are the minimum accepted to pass into this object. The routes` array is still the same as in Vue 2. It’s an array of routes, nothing has changed here. The createWebHashHistory()` function is now used to specify a Hash History mode in the Vue Router. As a side note, depending on what you are using in your app, there is also the `createWebHistory()` function that sets the mode to HTML 5. You can read more about History Modes. Next, we will update the scrollBehavior()` function as it has undergone some major changes. Replace the existing function with the following: `javascript scrollBehavior(to, from, savedPosition) { if (to.hash) { return { el: to.hash, behavior: "smooth" }; } else if (savedPosition) { return savedPosition; } else { return { top: 0 }; } } ` You can read more about Scroll Behavior in the Vue Router 4.0. Now, let’s run the app and see if everything works as expected. When I run the app, I get the following warning in the Dev Tools: `bash can no longer be used directly inside or . Use slot props instead: ` This warning has to do with Vue Router and the Transition component. You can read more about the Transitions in Vue Router. Let’s navigate to the App.vue` component and check what the current source code is: `html ` In Vue Router v4.0, you can no longer nest a ` component inside a `` component. The fix is simple and provided to you in the documentation. Replace the above with the following: `html ` These were all the steps needed to upgrade the Vue Meetup app. Others I’d like to draw your attention to a few more things when upgrading your apps to Vue 3. One of the components in the app had a single slot; that is, the default slot. The way it was used in the Vue 2 app was: `html ... … ... ` When I ran the app, the component was showing nothing, an empty screen! It seems Vue 2 was more tolerant by not forcing me to specify the name of the slot, even though this is the default slot. The quick fix in Vue 3 is as follows: `html ... ... ` Something else I didn’t mention is the Vuex v4.0. The same steps that we followed to upgrade the Vue Router can be followed here. The approach is similar. You can read more about the Vuex v4.0 Breaking Changes. Conclusion I am pretty sure we will all face more issues and encounter different hiccups while upgrading our apps. It will all depend on the features of your Vue 2. Remember, everything has a solution! While we wait for the Vue team to share an official migration guide, start trying to upgrade and see how you go. If you get stuck, feel free to drop me a message on twitter using my Twitter handle @bhaidar....

Being a CTO at Any Level: A Discussion with Kathy Keating, Co-Founder of CTO Levels cover image

Being a CTO at Any Level: A Discussion with Kathy Keating, Co-Founder of CTO Levels

In this episode of the engineering leadership series, Kathy Keating, co-founder of CTO Levels and CTO Advisor, shares her insights on the role of a CTO and the challenges they face. She begins by discussing her own journey as a technologist and her experience in technology leadership roles, including founding companies and having a recent exit. According to Kathy, the primary responsibility of a CTO is to deliver the technology that aligns with the company's business needs. However, she highlights a concerning statistic that 50% of CTOs have a tenure of less than two years, often due to a lack of understanding and mismatched expectations. She emphasizes the importance of building trust quickly in order to succeed in this role. One of the main challenges CTOs face is transitioning from being a technologist to a leader. Kathy stresses the significance of developing effective communication habits to bridge this gap. She suggests that CTOs create a playbook of best practices to enhance their communication skills and join communities of other CTOs to learn from their experiences. Matching the right CTO to the stage of a company is another crucial aspect discussed in the episode. Kathy explains that different stages of a company require different types of CTOs, and it is essential to find the right fit. To navigate these challenges, Kathy advises CTOs to build a support system of advisors and coaches who can provide guidance and help them overcome obstacles. Additionally, she encourages CTOs to be aware of their own preferences and strengths, as self-awareness can greatly contribute to their success. In conclusion, this podcast episode sheds light on the technical aspects of being a CTO and the challenges they face. Kathy Keating's insights provide valuable guidance for CTOs to build trust, develop effective communication habits, match their skills to the company's stage, and create a support system for their professional growth. By understanding these key technical aspects, CTOs can enhance their leadership skills and contribute to the success of their organizations....