nightwatch-visual-testing

Visual testing using NightwatchJS

This package allows you to perform visual testing using NightwatchJS, it internally extends nightwatch.js.

Whats new?

Just launched a new v2 of this package.

• Supports Nightwatch v2
• Additional feature of taking and comparing screenshot of any element, by passing the locator
• Removed dependency from nightwatch-api

Details and high-level working

• Perform visual testing using NightwatchJS
• Uses NightwatchJS provided built-in assertions and commands
• Uses assertions to capture screenshot of the page (DOM) and compares the screenshot against the reference (baseline) screenshot.
• If the baseline does not exists, it will be created the very first time you run the test and assertion will pass
• If the baseline does exists, the comparision of screenshot will be performed pixel to pixel and the difference would be shown in red.

Installation

• If using nightwatch v1, be sure to install using command:

npm install nightwatch-visual-testing@1

• For nightwatch v2, install:

npm install nightwatch-visual-testing

Configuration

1. Add custom command and assertion configuration to your nightwatch.conf.js. You can refer the link

  custom_commands_path: [
    './node_modules/nightwatch-visual-testing/commands'
  ],
  custom_assertions_path: [
    './node_modules/nightwatch-visual-testing/assertions'
  ]

2. Lastly pass the visual configuration, under the test_settings within the nightwatch.conf.js to be

default: {
  globals: {
    visual_regression_settings: {
      outputDir: './tests_output',
      threshold: 0.5
    },
  },

• outputDir : Refers to directory path, where the reports needs to be generated (Default: set to 'reports' directory)
• threshold: Refers to the matching threshold, which ranges from 0 - 1. Smaller the values makes the comparison sensitive (Default: set to 0.5)

Usage

To use the above, we simply need to use the custom assertion compareScreenshot or compareElementScreenshot.

1. The compareScreenshot currently accepts 2 parameter

Name	Type	Description
name (mandatory)	string	name of the test
message (mandatory)	string	message on sucess of the test

module.exports = {
  'Test dikshitashirodkar.com main content is correct': (browser) => {
    browser
      .url('https://dikshitashirodkar.com')
      .assert.compareScreenshot('First test', 'Screenshot captured!')
      .end()
  }
}

Note: Only available in the v2 of this package along with Nightwatchjs v2

2. The compareElementScreenshot accepts below parameters

Name	Type	Description
using (optional)	string	The locator strategy to use. See W3C Webdriver - locator strategies - default accepts css selector
selector (mandatory)	string	The CSS/Xpath selector used to locate the element.
name (mandatory)	string	name of the test
message (mandatory)	string	message on sucess of the test

Uses default css selector

module.exports = {
  'Test dikshitashirodkar.com main content is correct': (browser) => {
    browser
      .url('https://dikshitashirodkar.com')
      .assert.compareElementScreenshot('span[title="GitHub"]', 'Testing github logo', 'Captured screenshot OK!')
      .end()
  }
}

Uses any other locate strategy

module.exports = {
  'Test dikshitashirodkar.com main content is correct': (browser) => {
    browser
      .url('https://dikshitashirodkar.com')
      .assert.compareElementScreenshot('xpath', '//span[@title="GitHub"]', 'Testing github logo', 'Captured screenshot OK!')
      .end()
  }
}

Output

A baseline screenshots will be created for the very first time, under tests_output directory.

Note: This package works with NightwatchJS & NightwatchJS with CucumberJS integration too :)