Why singleton is blamed more than celebrated

Question

Hi

I am aware that singleton design pattern is useful in few scenarios like database connection , application logger as well as global application settings. However, It is singleton which gets criticized more than it is celebrated.

Below are some key points for its criticism:
1. Breaks Single responsibility ---> How ? Can you please share more insights?
2. Breaks testability ----> Why it hinders to test singleton?

Answer 1

Sure:

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1. Breaks SRP:
Singleton handles both instance control and business logic — two responsibilities.

2. Hurts Testability:
Hard to mock, creates hidden dependencies, and can cause shared state between tests.

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Use with care; DI is usually better.