Why testing should not be done by developers?

Related questions

1. What is fact in xUnit?
2. What is xUnit and NUnit?
3. What makes a good unit test?
4. Should I write unit tests?
5. Who is responsible for writing unit test cases?
6. What is xUnit testing in C#?
7. What is the purpose of xUnit?
8. Who Writes test cases in agile?
9. What should we unit test?
10. What is dotnet command?

Tags

1. #problems
2. #solving
3. #creating
4. #instead
5. #mindset
6. #spots
7. #destroying
8. #difficult
9. #which
10. #system
11. #important
12. #tester
13. #fixed
14. #building
15. #developers
16. #concerned
17. #makes
18. #locations
19. #breakable