What is Pester

What is Pester Unit testing framework ?

Pester is a Unit testing framework for Powershell development. Pester can be downloaded from Github project and imported to Powershell as a module. 
Pester uses a bunch of keywords and assertions to evaluate the code quality.Developer could follow TDD approach which is Test driven Development where Developers first write the test based on requirement and then write the development code. Initially test fails and then development code correction done to make the unit test pass.