Feature: Test improvements - Snapshots

[htmlandbacon]

What

We should look at adding light versions of visual regression, and code snapshots.

Following https://github.com/dwp/design-system/issues/486 a some work was done to understand visual regression in playwright.

We should now look at adding that to our pipeline, as this will well as out putting code snapshots.

Why

Following https://github.com/dwp/design-system/issues/486 some work was done internally how this would apply and while it won't catch everything it will help spot misalignments.

Snapshots of the code could be use to validate output from other implementations of the components.

Done when

• [ ] Visual regression testing for default examples are present (merged to develop)
• [ ] Code snapshots around default example are present for each component
• [x] Document update of approach on the repo
• [x] Integrated into CI build

Outcomes

We have a documented, approach to this, that excuses in our CI build

Related Links

• Introduction to Visual Regression Testing

[htmlandbacon]

This is enabled in our CI - however I'd class this as blocked till we have finished component reviews using https://jestjs.io/docs/snapshot-testing and https://playwright.dev/docs/test-snapshots

[htmlandbacon]

We'll keep going with this on a component by component bases, but no need to keep this open.