Feature/session service well known error

[FamALouiz]

Session Service: Well-Known Error Handling

Resolves #85

This PR introduces standardized error handling for the session service by creating well-known errors and updating both in-memory and database implementations to use them consistently.

Changes Made

1. Created Well-Known Errors (session/errors.go)

• Added ErrSessionNotFound - returned when a session cannot be found
• Moved ErrStateKeyNotExist - returned when a state key doesn't exist

2. Updated Session Service Implementations

Database Service (session/database/service.go)

• Modified Get() to return ErrSessionNotFound when gorm.ErrRecordNotFound is encountered
• Modified Delete() to return ErrSessionNotFound when no rows are affected (session doesn't exist)
• Improved error messages with contextual information (session ID)

In-Memory Service (session/inmemory.go)

• Updated Get() to return ErrSessionNotFound instead of generic error
• Updated AppendEvent() to return ErrSessionNotFound when session is not found
• Improved error messages with contextual information (session ID)

3. Test Improvements

Added Test Helper Function

• Created checkTestError() helper to eliminate code duplication across test files
• Uses t.Fatalf() for immediate test termination on error, ensuring consistent error handling
• Applied to both service_test.go and inmemory_test.go

Breaking Change Note

This changes the error behavior for Delete() operations - previously, deleting a non-existent session returned no error, but now returns ErrSessionNotFound. This aligns the behavior between database and in-memory implementations.

[gemini-code-assist[bot]]

Summary of Changes

Hello @FamALouiz, I'm Gemini Code Assist[^1]! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request focuses on enhancing the session service's error handling by introducing standardized, well-known error types. It centralizes common error definitions and updates both the database and in-memory session implementations to consistently utilize these new error types, particularly ErrSessionNotFound. This change significantly improves error clarity and consistency across the service, making it easier for consumers to identify and handle specific error conditions, and also includes improvements to test utilities.

Highlights

• Standardized Error Handling: Introduced ErrSessionNotFound and centralized error definitions in a new session/errors.go file, along with moving ErrStateKeyNotExist there.
• Database Service Updates: Modified Get() and Delete() methods in the database service to consistently return session.ErrSessionNotFound when a session is not found, improving error clarity and providing contextual session IDs.
• In-Memory Service Updates: Updated Get() and AppendEvent() methods in the in-memory service to also return session.ErrSessionNotFound for non-existent sessions, ensuring consistent error behavior across implementations.
• Test Utility Enhancement: Added a checkTestError() helper function to streamline error validation in test files (service_test.go and inmemory_test.go), reducing code duplication and ensuring consistent test error handling.
• Breaking Change Noted: The Delete() operation now returns ErrSessionNotFound when attempting to delete a non-existent session, which is a change from its previous behavior of returning no error.

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[FamALouiz]

/gemini review

[kdroste-google]

/gemini review

[FamALouiz]

I'll take a look at the requested changes and get this PR going. Thanks @kdroste-google

[FamALouiz]

/gemini review

[FamALouiz]

/gemini review