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Test Background

Test Background is a testing library based on the concept of RITEway and inspired by uvu.


I donโ€™t usually like to test, but I discovered is because tests frameworks out there are really messy and harder to use than they need to be. Learning about functional programming I ran into RITEway written by Eric Elliot and I really liked the approach of keeping every test very atomic, easy to read and strict, but I thought that having my own implementation would be hard so I just kept using the testing tools I was already using back then. But then Luke Edwards released uvu and he made me realize I could write a functional testing library, so I did.


The main idea behind this library is to follow a list of conventions for writing tests with the following shape:

  • Given: Description of the util being tested.
  • Must: Description of the expected output.
  • Received: We run the function and get the result.
  • Wanted: The result we expect.

Then the util test will take that object and using diff will either return nothing if all is ok, or give us a diff result we can then use to let the dev know about the issues found.

Because of the functional nature of this library, it can be used in the CLI or in the browser, the output can be formatted in whatever way the dev seems fit or use the default one.

To make it more useful it also is compatible with tsx to test TypeScript directly, and with c8 to get coverage for it.


I use this in all my open source libraries, and in some of my work libraries as well. You can check the /tests directory in any of my libraries to see how I use it.