Can you give an example of dependency injection for replacing a specific component implementation?

Dependency injection in Python is often implemented by passing a specific component implementation into the constructor or method of a class, which allows for easy replacement of this implementation when necessary.

Example:

class Database:
    def connect(self):
        pass

class MySQLDatabase(Database):
    def connect(self):
        print("Connecting to MySQL")

class MockDatabase(Database):
    def connect(self):
        print("Connecting to mock database for testing")

class Service:
    def __init__(self, db: Database):
        self.db = db

    def perform(self):
        self.db.connect()

# Using with a real database
service = Service(MySQLDatabase())
service.perform()  # Outputs: Connecting to MySQL

# Using with a mock object for testing
 test_service = Service(MockDatabase())
test_service.perform()  # Outputs: Connecting to mock database for testing

This approach allows for easy swapping of component implementations without changing the Service class code.