Testing Area/Visual regression testing

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Visual Regression Testing with BackstopJS

Set up:

  1. Create a new directory e.g. backstopjsmahara and cd into it
  2. Run npm i backstopjs
  3. Run backstop init
  4. Get the list of urls from your local site with this formula in the console in devtools: n=$$('a');for(u in n)console.log(n[u].href), or use a web scraper
  5. Copy and paste and turn these into a JavaScript array of strings as the value of urls in urls.js
  6. The urls.js file creates a scenarios.json file - run on cli with node urls.js
  7. Copy and paste the json array from the generated file into the backstop.json file as the value for "scenarios": (json array)
  8. INSERT HERE: Final state of backstop.json file and onReady.js script used in this context

We're going to start by running backstop reference - This will create reference screenshots for you to compare with when you run your test.

Then you can make your changes or checkout your test patch

Then you will run backstop test - this will take screenshots and compare them with your reference screenshots

For some reason the report tries to open in Matrix... But you can view the report results by opening the generated backstop_data/html_report/index.html in a browser.

Then you can run backstop approve - This will make all the tests become the reference files. Pass a --filter=<image_filename_regex> argument to promote only the test captures matching your scenario filename. The filenames (which by default include scenario and viewport names) are displayed in the visual and cli reports.