netlify-plugin-visual-diff

Check for visual diffs before deploying your site, in various browsers and responsive widths. Ensure that your CSS still works in all form factors and browsers before deployment, and record a visual history of your site. And do this without writing a single line of code using this plugin.

This plugin runs the Applitools Eyes visual tests using Cypress and checks whether the build if the new build is visually different from the previous run.

If you decide that the visual tests should fail your site, then the visual changes will need to be reviewed and approved in the Applitools Test Manager. Once they’re approved, rebuilding the site will succeed without errors from this plugin.

Why

CSS is hard. And so is building sites that work across all form factors. Id you want to be sure that your CSS and HTML changes are not breaking your site, you should check it for visual consistency by running a visual test.

Has that change in your CSS broken any of the tens of pages in your site? Only a visual diff can make sute that it hasn't, because going through all of them manually is certainly not an option. And if it was, you probably would miss something anyway. Only a visual diff would ensure that

Setup

NOTE: Before making these changes, you’ll need to enable the Build Plugins Beta.

If you're not already, register for Applitools Eyes at https://applitools.com/register
Login to the Eyes Test Manager at https://eyes.applitools.com/
Copy your Applitools API key from https://eyes.applitools.com/:

Create an environment variable in your Netlify site's settings called APPLITOOLS_API_KEY:
- Go to your site's page in Netlify
- Click on "Site settings"
- Expand "Build and deploy" in the nav bar on the right
- Click on "Environment" in the same nav bar, and click on "Edit variables"
- Add the APPLITOOLS_API_KEY variable along with the value you copied from Eyes.

In your netlify.toml, add the plugin:

[[plugins]]
  package = "netlify-plugin-visual-diff"

If you need to configure the plugin (see Configuration below), for example, to ignore date-related elements that should be ignored in the visual diff, use:
```
[[plugins]]
   package = "netlify-plugin-visual-diff"
   [plugins.inputs]
     ignoreSelector = "#today,.copyright"
```

Decide which browsers and form factors you want to check your site on (by default, it will be tested on the latest Chrome, with a 1024x768 viewport), and define them in the netlify.toml:

[[plugins]]
 package = "netlify-plugin-visual-diff"
 [plugins.inputs]
   ignoreSelector = "#today,.copyright"

   [[plugins.inputs.browser]]
     name = "chrome"
     width = 1024
     height = 768

   [[plugins.inputs.browser]]
     name = "firefox"
     width = 1920
     height = 1080

   [[plugins.inputs.browser]]
     deviceName = "iPhone X"

For a full list of browsers and configurations, see https://www.npmjs.com/package/@applitools/eyes-cypress#configuring-the-browser

That's it! Your next deploys will be visually checked on all the browsers and form factors you specified, and if there is a diff, the build will fail and a link to the Visual test will be added to the build so that you can verify that there is a problem, or approve the changes so that your next build will succeed.

Note: if you want the visual test not to fail the build but to just execute the visual test so that you can see the result in the Eyes Test Manager, add failBuildOnDiff to the configuration, thus:
[[plugins]]
  package = "netlify-plugin-visual-diff"
  [plugins.inputs]
    failBuildOnDiff = false

Configuration

The Netlify Visual Diff plugin is a no-touch solution: you just add it to your netlify.toml, and you're good to go. But it is configurable, using the following configurations:

serverUrl: if you're using the public Applitools server eyesapi.applitools.com, there is no need to configure this, but if you're an Applitools enterprise user with a dedicated server, put the server URL here, e.g. https://acustomerapi.applitools.com. Default: https://eyesapi.applitools.com.
ignoreSelector: if you wish the diff to ignore certain regions when diffiing, specify a selector that defines which elements to ignore (remember you can have a selector with multiple elements using a ,), e.g. ignoreSelector = "#today,.copyright". Default: none.
failBuildOnDiff: if you wish to only run the Visual test (to see the result in the Eyes manager), without it failing the build, set this to false, e.g failBuildOnDiff = false. Default: true.
concurrency: specify a higher level of concurrency to make the test faster. For more information, see https://www.npmjs.com/package/@applitools/eyes-cypress#concurrency.
browser: an array of browsers. For more information, see https://www.npmjs.com/package/@applitools/eyes-cypress#configuring-the-browser.

The default configuration, if none is specified, is:

[[plugins]]
  package = "netlify-plugin-visual-diff"
  [plugins.inputs]
    serverUrl = "https://eyesapi.applitools.com" # The public Eyes server
    ignoreSelector = "" # There is no null in TOML, but if there were, then it would be null
    failBuildOnDiff = true
    concurrency = 1
    [[plugins.inputs.browser]]
      name = "chrome"
      width = 1024
      height = 768