1. Unit testing is a level of software testing where individual units/components of the software are tested. The purpose is to validate that each unit of the software performs as designed.
   Automation testing is an automatic technique where the tester writes scripts on their own and uses suitable software to test the software. It is basically an automation process of a manual process.
   Manual testing is a process of finding out the defects or bugs in a software program. In this method, the tester plays an important role of end user and verifies that all the features of the application are working correctly.
2. Unittest, mock, nose, pytest.
3. A test case is a set of actions executed to verify a particular feature or functionality of your software application. This tutorial describes test case designing and the importance of its various components.
4. PEP 8 is Python's style guide. It's a set of rules for how to format your Python code to maximize its readability. Writing code to a specification helps to make large code bases, with lots of writers. It is more uniform and predictable, too.