Automated Visual Testing for React Storybook using Screener.io
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README.md

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Automated Visual Testing for Storybook (React, Vue or Angular) using Screener.io.

Screener-Storybook will use your existing Storybook stories as visual test cases, and run them against Screener's automated visual testing service. Get visual regression tests across your React, Vue or Angular components with no additional coding!

Installation

  1. Go to https://screener.io/v2/new
  2. Follow the steps in the wizard to setup a New Project

Run

When your project is setup, you can run a test with the following command:

$ npm run test-storybook

Docs


Testing Interactions

To test interactions, you can add steps to your existing Storybook stories. Each step is an instruction to interact with the component. This is useful for clicking buttons, filling out forms, and getting your components into the proper visual state to test. This also keeps your stories and interaction test code in the same place.

With React

To add steps to a React story, wrap your component within a Screener component, and pass it a steps prop. The steps can then be generated using our fluent API below.

Here is an example:

import Screener, {Steps} from 'screener-storybook/src/screener';

storiesOf('MyComponent', module)
  .add('default', () => (
  	<Screener steps={new Steps()
    	.click('.selector')
    	.snapshot('name')
    	.end()
    }>
      <MyComponent />
    </Screener>
  ));
With Vue

To add steps to a Vue story, add a steps prop to the story object being returned. The steps can then be generated using our fluent API below.

Here is an example:

import Steps from 'screener-runner/src/steps';

storiesOf('MyComponent', module)
  .add('default', () => ({
  	render: h => h(MyComponent),
    steps: new Steps()
    	.click('.selector')
        .snapshot('name')
        .end()
  }));
With Angular

To add steps to an Angular story, add a steps prop to the story object being returned. The steps can then be generated using our fluent API below.

Here is an example:

import * as Steps from 'screener-runner/src/steps';

storiesOf('MyComponent', module)
  .add('default', () => ({
    component: MyComponent,
    props: {},
    steps: new Steps()
    	.click('.selector')
        .snapshot('name')
        .end()
  }));

Steps

The following step methods are currently available. Methods with selectors have built-in waits to simplify test flow creation:

  • click(selector): this will click on the first element matching the provided css selector.
  • snapshot(name, [options]): this will capture a visual snapshot.
    • Optional options param can contain a cropTo field:
    .snapshot('open', {cropTo: '.selector'})
  • hover(selector): this will move the mouse over the first element matching the provided css selector.
  • mouseDown(selector): this will press and hold the mouse button over the first element matching the provided css selector.
  • mouseUp(selector): this will release the mouse button. selector is optional.
  • focus(selector): this will set cursor focus on the first element matching the provided css selector.
  • setValue(selector, value, [options]): this will set the value of the input field matching the provided css selector.
    • Optional options param can contain an isPassword option:
    .setValue('.selector', 'text', {isPassword: true})
  • keys(selector, keys): this will send the provided keys to the first element matching the provided css selector.
  • executeScript(code): this executes custom JS code against the client browser the test is running in. The code parameter is a string.
  • ignore(selector): this ignores all elements matching the provided css selector(s).
  • wait(ms): this will pause execution for the specified number of ms.
  • wait(selector): this will wait until the element matching the provided css selector is present.
  • waitForNotFound(selector): this will wait until the element matching the provided css selector is Not present.
  • cssAnimations(isEnabled): this will override the global cssAnimations option for the current UI state. Set to true to enable CSS Animations, and set to false to disable.
  • rtl(): this will set the current UI state to right-to-left direction.
  • ltr(): this will set the current UI state to left-to-right direction.
  • end(): this will return the steps to be run.

Note: When adding Steps using the fluent API, you must end the method chain with end().

Testing Responsive Designs

To test against multiple resolutions or devices, you can add resolutions to your screener configuration file, with an array of resolutions.

Each resolution item in the array is either:

  • A string in the format: <width>x<height>. Example: 1024x768
  • Or an object with Device details: deviceName and optional deviceOrientation

Here is an example:

module.exports = {
  ...

  resolutions: [
    '1024x768',
    {
      deviceName: 'iPhone 6'
    },
    {
      deviceName: 'iPhone 6 Plus',
      deviceOrientation: 'landscape'
    }
  ]
};

Available Devices

deviceName can be one of the following values:

iPad iPhone 4 Galaxy S6 Nexus 4
iPad Pro iPhone 5 Galaxy S7 Nexus 5
iPhone 6 Galaxy S8 Nexus 5X
iPhone 6 Plus Nexus 6P
iPhone 7 Nexus 7
iPhone 7 Plus Nexus 10
iPhone 8
iPhone 8 Plus
iPhone X

Note: In Storybook v4.x, you need to add the viewport meta tag for the browser to scale the UI correctly. You can do this by creating a file called preview-head.html inside the Storybook config directory and adding the following:

<meta name="viewport" content="width=device-width, initial-scale=1.0">

Cross Browser Testing

Overview

For Cross Browser Testing, Screener provides cloud browsers and device emulators. The following browsers are available:

  • Chrome
  • Firefox
  • Internet Explorer 11

To test against additional browsers, Screener provides integrations with Sauce Labs and BrowserStack to provide access to Safari and Edge browsers. For more information, view the Sauce Labs Integration or BrowserStack Integration documentation.

Cross Browser Testing is available through Screener's Perform plan. By default, Screener runs tests against the Chrome browser.

Adding Browsers

To test against multiple browsers, add the browsers option to your screener.config.js file:

// screener.config.js
module.exports = {
  ...

  browsers: [
    {
      browserName: 'chrome'
    },
    {
      browserName: 'firefox'
    },
    {
      browserName: 'internet explorer',
      version: '11'
    }
  ]
};

Supported Browsers

browserName version
chrome -do not set-
firefox -do not set-
internet explorer 11
microsoftedge 17.17134 requires Sauce Labs or BrowserStack Integration
safari 11.1 requires Sauce Labs or BrowserStack Integration

Additional Configuration Options

Note: Screener will automatically set build, branch, and commit options if you are using one of the following CI tools: Jenkins, CircleCI, Travis CI, Visual Studio Team Services, Codeship, GitLab CI, Drone, Bitbucket Pipelines, Semaphore, Buildkite.

  • build: Build number from your CI tool (see note above). Screener will auto-generate a Build number if not provided.
  • branch: Branch name being built (see note above).
  • commit: Commit hash of the build (see note above).
  • resolution: Screen resolution to use. Defaults to 1024x768
    • Accepts a string in the format: <width>x<height>. Example: 1024x768
    • Or accepts an object for Device Emulation. Example:
    resolution: {
      deviceName: 'iPhone 6'
    }
    • deviceOrientation option also available. Can be portrait or landscape. Defaults to portrait.
  • resolutions: Array of resolutions for Responsive Design Testing. Each item in array is a resolution, either string or object format.
    • See "Testing Responsive Designs" above for an example
    • Note: resolution and resolutions are mutually exclusive. Only one can exist.
  • cssAnimations: Screener disables CSS Animations by default to help ensure consistent results in your visual tests. If you do not want this, and would like to enable CSS Animations, then set this option to true.
  • ignore: Comma-delimited string of CSS Selectors that represent areas to be ignored. Example: .qa-ignore-date, .qa-ignore-ad
  • hide: Comma-delimited string of CSS Selectors that represent areas to hide before capturing screenshots. Example: .hide-addon-widget, .hide-ad
  • baseBranch: Optional branch name of your project's base branch (e.g. master). Set this option when developing using feature branches to:
    • automatically compare and accept changes when merging a feature branch into the base branch, or when rebasing a feature branch.
    • automatically pull the initial baseline of UI states for a feature branch from this base branch.
  • includeRules: Optional array of RegExp expressions to filter states by. Rules are matched against state name. All matching states will be kept.
    • Example:
    includeRules: [
      /^Component/
    ]
    • Note: includeRules can be added as a property to objects in browsers or resolutions in order to filter states specifically by a browser or resolution.
  • excludeRules: Optional array of RegExp expressions to filter states by. Rules are matched against state name. All matching states will be removed.
    • Example:
    excludeRules: [
      /^Component/
    ]
    • Note: excludeRules can be added as a property to objects in browsers or resolutions in order to filter states specifically by a browser or resolution.
  • diffOptions: Visual diff options to control validations.
    • Example:
    diffOptions: {
      structure: true,
      layout: true,
      style: true,
      content: true,
      minLayoutPosition: 4, // Optional threshold for Layout changes. Defaults to 4 pixels.
      minLayoutDimension: 10, // Optional threshold for Layout changes. Defaults to 10 pixels.
      minShiftGraphic: 2, // Optional threshold for pixel shifts in graphics.
      compareSVGDOM: false // Pass if SVG DOM is the same. Defaults to false.
    }
  • failOnNewStates: Option to set build to failure when new states are found, and to disable using new states as a baseline. Defaults to true.
  • alwaysAcceptBaseBranch: Option to automatically accept new and changed states in base branch. Assumes base branch should always be correct.
  • failureExitCode: The exit code to use on failure. Defaults to 1, which will fail a CI build.
    • To NOT fail a CI build on Screener failure, set to 0. Example:
    failureExitCode: 0
  • browsers: Optional array of browsers for Cross Browser Testing. Each item in array is an object with browserName and version properties.
    • browserName and version must match one of the supported browsers/versions in the browser table above.
    • Example:
     browsers: [
       {
         browserName: 'chrome'
       },
       {
         browserName: 'safari',
         version: '11.1'
       }
     ]
  • ieNativeEvents: Option to enable native events in Internet Explorer browser. Defaults to false.
  • sauce: Optional Sauce Labs credentials for Cross Browser Testing.
    • Example:
    sauce: {
      username: 'sauce_user',
      accessKey: 'sauce_access_key',
      maxConcurrent: 10 // optional available concurrency you have from Sauce Labs
    }
  • vsts: Optional configuration for integrating with Visual Studio Team Services.
    • Example:
    vsts: {
      instance: 'myproject.visualstudio.com'
    }