It's true that Racket unit tests are an optional module within the standard library, but the command line tools and package system work directly with it. You can place unit tests right alongside the regular code but within a specially-named "test" submodule, so the unit test code doesn't run at runtime by default, except in certain contexts (package installation, "raco test" command, or running the file from within the Racket IDE).
Yea, I like this about Racket unit tests. It really lowers the barrier to writing tests, and you don't have to go creating separate test files in specific locations.
It's true that Racket unit tests are an optional module within the standard library, but the command line tools and package system work directly with it. You can place unit tests right alongside the regular code but within a specially-named "test" submodule, so the unit test code doesn't run at runtime by default, except in certain contexts (package installation, "raco test" command, or running the file from within the Racket IDE).