How to properly divide tests into unit and integration tests

[ua-kxie]

Should unit tests really be put in the same file as the source?

The Rust Programming Language states the following: You’ll put unit tests in the src directory in each file with the code that they’re testing. The convention is to create a module named tests in each file to contain the test functions and to annotate the module with cfg(test) . The average loc per file in my project is pretty high, the amount of loc from unit tests is more than double that of the actual code. How should I proceed to enhance the maintainability and the readability of my code…

Integration tests are not limited to integration between systems being developed and external systems. It can also cover integration of different parts of your own code.

Integration testing - Rust By Example