Unit Testing and Mock Testing
When a developer starts writing code, they need to ensure it is tested correctly at the unit level. It may happen that the boundary conditions are missed, and the code may break when it runs on the client's site. To avoid this situation, generally, it is a good idea to do unit testing for the code. Unit testing is testing that's performed at the unit level or the base level of the code where a developer can test their code in an isolated environment, assuming the required setup has been fulfilled to run a feature of the code. Generally, it is good practice to break down modules into small functions and test each function separately.
For example, suppose part of the functionality is to read the configuration file and get the environment set up with the parameters from the configuration file. We can create a dedicated function to write this functionality. So, to test this function, we can create a set of unit test cases that will check various combinations...