Solving mockResolvedValue is not a function Error in Jest with TypeScript

Discover how to resolve the `mockResolvedValue is not a function` error when partially mocking modules in Jest with TypeScript. Find a clear solution and best practices for mocking methods effectively.
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Resolving the mockResolvedValue is not a function Error in Jest with TypeScript

Unit testing is a critical aspect of software development, ensuring that individual components of your application work as intended. However, when using Jest in combination with TypeScript, you may encounter some frustrating issues. One such common problem is the error message: mockResolvedValue is not a function. If you've found yourself in this situation while trying to partially mock a module, don’t worry! This guide will guide you through the solution.

Understanding the Problem

The error message you are probably seeing looks something like this:

[[See Video to Reveal this Text or Code Snippet]]

This typically occurs when you attempt to partially mock a module and set a return value for a specific mocked method using mockResolvedValue. The code you provided might resemble the following:

[[See Video to Reveal this Text or Code Snippet]]

However, despite correctly mocking the method, when you run your tests, Jest throws an error stating that .mockResolvedValue is not a function.

The Solution

Step 1: Remove the Top-Level Mock

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Write Your Tests

Conclusion

Testing is an essential practice in maintaining the quality and reliability of your code, so embrace these techniques and ensure your tests remain efficient and effective!

Happy testing!