Discussion on Test Coverage in Domain Layer

[coderabbitai]

This issue is created based on the conversation in PR #73 at this comment.

User @zhumeisongsong would like to discuss the purpose and value of adding tests in the domain layer, specifically related to email validation in libs/users/domain/src/lib/user.entity.spec.ts.

The discussion focuses on whether it's appropriate to add tests in the domain layer when validation logic resides in the infrastructure layer (e.g., Mongoose schemas). The goal is to determine the best practices for test placement in relation to where the corresponding logic is implemented.