mockImplementation
mockImplementation is a method used in JavaScript testing frameworks, particularly Jest, to provide a custom implementation for a mocked function. When you mock a function, you often want to control its behavior during tests, rather than letting it execute its original code. mockImplementation allows you to define exactly what the mocked function should do. This can include returning specific values, throwing errors, or performing complex logic that mimics the original function's behavior under certain conditions.
The primary use case for mockImplementation is to isolate the code being tested from its dependencies. By
mockImplementation can accept a function as its argument. This function will be executed whenever the mocked
In contrast to mockReturnValue or mockResolvedValue, which are simpler ways to define a static return value,