Unit test: cannot delete a copied file

Yu Hou 1

hi, I am writing an unit test to test a very simple application. The application is very simple. It only have two public APIs:

OpenFile API: copy an existing binary file to a new created temp file and read it.
CloseFile API: close both files and delete the temp file created in OpenFile API.

While running/debugging the application, both APIs work fine. CloseFile API can delete the temp file without any issue. While I created an Unit test project to try to test the application's two APIs. In my test case, I just call both APIs 100 times (repeat open file and close file). But while calling CloseFile API, it always throw exceptions at the point deleting temp file by saying the file is being opened by other program. To test it further, I wrote another console app to call the two APIs 100 time (same logic as unit test). No issue at all.

Do you know why?

Thanks,
Yu

Tianyu Sun-MSFT 31,246 Reputation points Microsoft Vendor

2022-10-21T05:33:54.16+00:00

Hi @Yu Hou ,

Welcome to Microsoft Q&A forum. Could you share us some code snippets to check further? Ideally, the order in which unit tests run should not matter, and it is best practice to avoid ordering unit tests. Are your unit test codes written to be run in a specific order?
Yu Hou 1 Reputation point

2022-10-22T02:50:43.55+00:00

It is not about unit test order. The situation is, my own app (to be tested by unit test project) can delete temp file at CloseFile time without an issue. When my app's CloseFile API is called from unit test project, the temp file cannot be deleted with error that access is not allowed. I have no idea why this happens. Thanks.
Tianyu Sun-MSFT 31,246 Reputation points Microsoft Vendor

2022-10-25T09:52:42.427+00:00

Hi @Yu Hou ,

Does it pass, if you only call the two APIs 1 time? Could you share a minimal sample project with us to reproduce this issue?

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Unit test: cannot delete a copied file

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