Optionally ignore whitespaces in snapshot tests (more flexible snapshots)

💬 Questions and Help

I teach React.js to hundreds of students, all exercises are auto-graded using Jest as testing engine. The problem is that Jest snapshots are to sensitive about spaces. If the student solution is:

<span>    Hello World</span>

Instead of

<span>Hello World</span>

Jest will raise an error.

Is it possible to tell jet to be more flexible? Students constantly get stuck because they have to keep trying to match the exact solution character by character. Or maybe use the --config to tell jest to prettify the student code before testing it?

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[rogeliog]

I wonder if you could write a snapshot serializer that would trim the whitespaces of whenever there is a React element with text as is children.

[rogeliog]

Jest snapshots serializers use the pretty-format package, which also lives inside the Jest repository

Here are some links that might be useful.

• Pretty format documentation
• Using Pretty format with Jest, this shows how to write a serializer, which pretty-format calls a plugin.
• Pretty Format out of the box plugins

Let me know if that doesn’t help and I’m happy to provide more specific details