Making private members public just for testing breaks encapsulation, one of the fundamental principles of object-oriented programming. When you
change a private method or variable to public, you expose internal implementation details that were intentionally hidden.
Encapsulation helps maintain code quality by:
- Hiding internal implementation details from other classes
- Preventing unintended access to sensitive logic or data
- Making it easier to refactor internal code without affecting external dependencies
- Clearly defining the public interface of a class
When private members are made public for testing, they become part of the class’s public API, even though they weren’t designed for external use.
This can lead to:
- Other developers accidentally using these "internal" methods in production code
- Increased coupling between classes
- Difficulty in refactoring, as changing these methods might break code that shouldn’t depend on them
- Confusion about what constitutes the intended public interface
Salesforce provides the @TestVisible annotation specifically to address this testing challenge. This annotation allows private members
to be accessed from test classes while keeping them private in all other contexts. It’s a clean solution that maintains encapsulation while enabling
comprehensive testing.
What is the potential impact?
Breaking encapsulation can lead to tightly coupled code that is harder to maintain and refactor. It may also result in unintended dependencies on
internal implementation details, making the codebase more fragile and prone to bugs when internal logic changes.
