Using Pester (a PowerShell testing framework) - https://github.com/pester/Pester, write tests for the following 3 scenarios:

1.No files exist in the source folder then run the function test that a warning was issued

2.The following files were in the source folder (apple.txt,pear.txt,1234.txt) run the function test the output is correct according to the expected behavior for the function

3.The following files were in the source folder (apple.txt. bobcat.txt) run the function test the output is correct according to the expected behavior run the function again test the output is correct according to the expected behavior of the function