[Docs]: Component testing "best practices" or "pitfalls"

[sand4rt]

Page(s)

Page: https://playwright.dev/docs/next/test-components#update

I think these topics would be useful to mention:

• Determine what to test
• Determine what not to test (implementation details)
• How to name tests
• Use the appropriate locator
• Emphasise emulation over mocking
• Avoid nesting / describe blocks
• Avoid unnecessary abstractions (Test isolation)
• Ensure your test can fail

@dgozman do you have other topics/changes in mind?

Description

Suggestion from @dgozman to include a "best practices" or "pitfalls" section for component testing: https://github.com/microsoft/playwright/issues/31339#issuecomment-2174162872. I've created a ticket to track this so I don't forget.

[dgozman]

do you have other topics/changes in mind?

This looks like a good starting point. If anything, some of these topics might be relevant in e2e best practices as well.