Cypress ODiff

A plugin for adding visual regression test to Cypress using ODiff The fastest pixel-by-pixel image visual difference tool in the world.

Why?

ODiff Benchmarks are the main motivation for this. 🚀

Getting Started

Install:

$ npm install cypress-odiff

Add the plugin

const { addCompareScreenshotPlugin } = require('cypress-odiff')

module.exports = defineConfig({
  trashAssetsBeforeRuns: false, // needed to avoid deleting expeted screenshot
  e2e: {
    setupNodeEvents (on, config) {
      addCompareScreenshotPlugin(on, config)
    }
  }
})

Add the command in support/commands.js

const { addCompareScreenshotCommand } = require('cypress-odiff')

addCompareScreenshotCommand({})

Using in Tests

Given the following test case under cypress/e2e/example.cy.js

describe('example', () => {
  it('passes', () => {
    cy.visit('https://example.cypress.io')
    cy.compareScreenshot()
  })
})

the command compareScreenshot will:

• create a screenshot (expected) under cypress/screenshots/example.cy.js/passes.png and save it for further runs
• if the screenshot is already created, the command will compare the recorded screenshot (actual) with the previously saved one (expected) and fail if there is a difference between these two screenshots. An image with the highlighted differences (diff) will be created.

Options

compareScreenshot accepts an options object with the following keys:

• screenshotOptions: will be passed to cy.screenshot() command to capture screenshot. see Cypress screenshot options docs.
• compareOptions: will be passed to compare method from package. see ODiff Nodejs.
• pluginOptions: These options define how this plugin should behave.

Plugin Options

| name | default | | |---|---|---| | customSnapshotsDir | "cypress/snapshots" | should be under cypress directory. .expected, .actual, .diff screenshots will be saved under this path. | | updateSnapshots | undefined | if true, plugin will save the screenshot with .expected suffix and this image will be used for furthur visual regressions tests | | failOnExpectedMissing | undefined | if true the test will fail when .expected screenshot does not exist. This is particulary usefull when running test on ci.|