TDD Excel File Download API with Flask

Test-driven development (TDD) is a very useful development technique. However, some features are particularly difficult to test. One example is to download files.
Recently, I have just “TDDed” a file download feature in python Flask. During development, there was not a complete guide on how to TDD it. So to help save effort and time for other engineer friends, this blog will give a simplified example of using TDD to drive an excel file download API.

https://medium.com/abetterconsultancy/tdd-excel-file-download-api-with-flask-d432bb72e888