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3142 :: Testing private functions

• RedFred (orginal) [2017-09-02T14:00:12+02:00] view original

  Given I have my tests in a separate file to my application code, is there any way to test unexported (private) procs from within my test file?

  i.e.

  proc private(x: int): int =
  Run

  without doing

  proc private*(x: int): int =
  Run

  Is there any tip/trick I'm missing, what is the standard practice for testing private functions?

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• dom96 (orginal) [2017-09-02T14:02:50+02:00] view original

  There is not. But I don't think it's correct to be testing private functions, testing the public ones should be enough.

  The only way to test them is to put the tests in the same file.

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• RedFred (orginal) [2017-09-02T14:09:03+02:00] view original

  ok, thank you, just needed to confirm.

  One thing I'm thinking of is putting my private function tests in my main file under a when testPrivateFuncs: block and building with this symbol, when I need peace of mind.

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• Jehan (orginal) [2017-09-02T15:04:51+02:00] view original

  You may be able to use include instead of import for this purpose.

  Note that include and import have different semantics. With include, you have basically textual inclusion. This means that multiple includes will replicate procedures and variables each time. However, if you're only using it for unit tests, that may already be sufficient.

  In addition, this allows you to keep separate modules with and without testing and without duplicating code. For example:

  1. Put your basic modules into a directory modules/base (or whatever path you like).
  2. Create a separate directory modules/withtests that contains one module for each in modules/base, where the testable one includes the original via include ../base/original and adds tests as needed.
  3. Compile with --path set to either modules/base or modules/withtests depending on whether you're building a release or test version.

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• RedFred (orginal) [2017-09-02T19:40:10+02:00] view original

  @Jehan: thank you, I tried this and it works a treat. I get clean code/test separation with a /src and /test directories and all I have to do is build and run my test/module.nim and the included src/module.nim will be compiled and then the tests will run. Very nice, thanks for the tip!

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• cdunn2001 (orginal) [2017-09-05T19:37:51+02:00] view original

  Just test the private parts from within its own file. That's a nice way to write some peace-of-mind tests. (Testing an implementation detail is not always a bad idea.)

  when isMainModule:
    test_private()
  Run

  Another example:

  • https://forum.nim-lang.org/t/1303

  You might want to exclude the test from compilation to save time, but dead-code elimination can remove it from the shipped code anyway.

  To run the test, you will have to build that module as an executable, but then you simply execute it.

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• RedFred (orginal) [2017-09-07T12:14:33+02:00] view original

  @cdunn2001, so far @Jehan's suggestion works nicely for me but this is another good idea, thank you. I didn't want the same code to be compiled twice but I'd forgotten about dead-code elimination. I feel much happier when my implementation functions have also been tested. :)

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