Refactor test files for improved readability and consistency

- Removed unnecessary blank lines and adjusted formatting in test files.
- Ensured consistent use of commas in function calls and assertions across various test cases.
- Updated import statements for better organization and clarity.
- Enhanced mock setups in tests for better isolation and reliability.
- Improved assertions to follow a consistent style for better readability.

app/utils/credit_decorators.py

@@ -5,7 +5,7 @@ from collections.abc import Awaitable, Callable
 from typing import Any, TypeVar
 
 from app.models.credit_action import CreditActionType
-from app.services.credit import CreditService, InsufficientCreditsError
+from app.services.credit import CreditService
 
 F = TypeVar("F", bound=Callable[..., Awaitable[Any]])
 
@@ -69,7 +69,7 @@ def requires_credits(
 
             # Validate credits before execution
             await credit_service.validate_and_reserve_credits(
-                user_id, action_type, metadata
+                user_id, action_type, metadata,
             )
 
             # Execute the function
@@ -85,7 +85,7 @@ def requires_credits(
             finally:
                 # Deduct credits based on success
                 await credit_service.deduct_credits(
-                    user_id, action_type, success, metadata
+                    user_id, action_type, success, metadata,
                 )
 
         return wrapper  # type: ignore[return-value]
@@ -173,7 +173,7 @@ class CreditManager:
     async def __aenter__(self) -> "CreditManager":
         """Enter context manager - validate credits."""
         await self.credit_service.validate_and_reserve_credits(
-            self.user_id, self.action_type, self.metadata
+            self.user_id, self.action_type, self.metadata,
         )
         self.validated = True
         return self
@@ -184,9 +184,9 @@ class CreditManager:
             # If no exception occurred, consider it successful
             success = exc_type is None and self.success
             await self.credit_service.deduct_credits(
-                self.user_id, self.action_type, success, self.metadata
+                self.user_id, self.action_type, success, self.metadata,
             )
 
     def mark_success(self) -> None:
         """Mark the operation as successful."""
-        self.success = True
+        self.success = True