Change unittest to pytest

[OlivieFranklova]

difference here

Parameter	pytest	unittest
Test Discovery	pytest has an intelligent and automatic test discovery feature. It can find and run test cases based on naming conventions and folder structures, reducing the need for manual configuration.	unittest also provides test discovery, but it might require more explicit configuration and setup.
Test Writing	pytest allows you to write test functions using plain Python functions. It offers a variety of powerful features like fixtures for setting up test contexts, parameterized testing, and advanced assertion introspection.	unittest uses classes and methods for defining test cases. While this provides a structured approach, some developers find the syntax slightly more verbose than pytest.
Assertion Syntax	pytest provides clear and expressive failure messages with detailed information on what went wrong. Its assertion introspection helps in quickly identifying issues.	unittest also provides assertion methods, but the failure messages might not be as informative as those in pytest.