Scenario:

You are required to implement a logging system in a NestJS application that allows switching between different logging implementations based on an environment variable. The system should use dependency injection to manage these implementations.

Task:

1. Interface Definition:

   • Define an interface ILogger with a single method logError.

2. Concrete Implementations:

   • Implement at least two concrete classes that adhere to the ILogger interface. For example, ConsoleLogger and FileLogger.

3. Dependency Injection:

   • Set up these implementations to be injected into the application at startup.
   • Use an environment variable to determine which implementation should be used.

4. Configuration:

   • Demonstrate how the application can switch between these implementations based on the value of the environment variable.

5. Testing:

   • Set up a unit test framework of your choice (e.g., Jest).
   • Write unit tests to verify the behavior of your logging implementations and the configuration logic.

Expectations:

• Clean Code: Ensure your code is clean, well-organized, and adheres to best practices.
• Good Commit Pattern: Follow a clear and logical commit pattern.
• Accurate Implementation: The implementation should meet the requirements accurately.
• Testing: Show how the implementation can be tested, and provide example tests.

Deliverables:

1. Source code with the interface and implementations.
2. Configuration setup demonstrating environment-based switching.
3. Unit tests for the implementations and configuration logic.
4. A brief documentation of your thought process and any assumptions made.

Time Frame:

You have about 12 hours from task reception to complete this task.