Using a common Catch main object for development.

[arcuru]

This needed a few small changes from my hacked together test. Mostly I hit an issue where I couldn't create a catchlib object in every exercise during a full CMake build, so I had to switch how I did the individual exercise CMakeLists.txt files.

I added some comments into the students' CMakeLists files, but they may need to be phrased better to be clearer to them. I wanted to explain what it was instead of just confusing the student if they looked at it.

Closes #272

[KevinWMatthews]

Ah, yes - you would need to name each library uniquely. Normally that's no issue, but in our case that is much harder to maintain.

I think that we're correct to omit special compiler flags or definitions from catchlib: -Wall -Wextra -Wpedantic -Werror or _SCL_SECURE_NO_WARNINGS. Those are useful in student code but not for this.

Looks pretty good at a read. Hope to try this in detail this evening.

[KevinWMatthews]

@patricksjackson I'm getting failures when I build individual exercises in isolation (using only the exercise-level CMakeLists.txt, not using the root-level CMakeLists.txt).

Can you reproduce this:

CMake Error at CMakeLists.txt:26 (add_executable):
  Error evaluating generator expression:

    $<TARGET_OBJECTS:catchlib>

  Objects of target "catchlib" referenced but no such target exists.

using something like:

$ cd exercises/beer-song/
$ cmake .

[KevinWMatthews]

I think it's a quirk of CMake conditionals. When building from the root level, EXERCISM_COMMON_CATCH exists and is Boolean. When building at the exercise level, EXERCISM_COMMON_CATCH does not exist at all.

Reading through CMake's documentation on if() and variable references but haven't gotten to the bottom of it yet.

[KevinWMatthews]

Short story - got off in the weeds above.

I think we need to reverse the order of the conditional for isolated exercises to build properly:

# Use the common Catch library?
if(${EXERCISM_COMMON_CATCH})
    # For Exercism track development only
    add_executable(${exercise} ${file}_test.cpp ${exercise_cpp} ${file}.h $<TARGET_OBJECTS:catchlib>)
else()
    # Build executable from sources and headers
    add_executable(${exercise} ${file}_test.cpp ${exercise_cpp} ${file}.h test/tests-main.cpp)
endif()

because if (NOT <expr>) behaves differently that if (<expr>).

[KevinWMatthews]

There are some CMake if semantics here. I see this succeed:

if(NOT EXERCISM_COMMON_CATCH)

this fail:

if(NOT ${EXERCISM_COMMON_CATCH})

and this succeed:

if(NOT "${EXERCISM_COMMON_CATCH}")

Do you see something similar? This is when building as a student would - only one specific CMakeLists.txt file.

[arcuru]

I alwyas like to work with CMake occasionally to remind me how much I hate it. That test is identical to the one elsewhere in the file that tests the run all tests option, except it has a NOT in it.

I think the problem is CMake for evaluates the branch in some instances, even if it's not taken? No idea.

Regardless, I added a test to CI to run it from an individual directory, and updated the exercise CMakeLists to what you suggested actually works.

Also changing the title to WIP, I need to test this on Visual Studio because I now don't trust this will work everywhere, I'll change it back after confirming.

[arcuru]

Oh, I need to fix how I did the testing of an individual test anyways.

[arcuru]

Works fine in Visual Studio too.

I added running the individual test in CI to #279, since it requires a compilable hello-world anyways.

[KevinWMatthews]

I alwyas like to work with CMake occasionally to remind me how much I hate it.

There's always Autotools ;)

That test is identical to the one elsewhere in the file that tests the run all tests option, except it has a NOT in it.

I don't know for certain, but I think that if (NOT) has different variable expansion rules than if (). Counterintuitive, I agree.

[KevinWMatthews]

Good overall.

One possible change for consistency but it isn't required.

[arcuru]

I missed that this was actually all finished apparently. I've updated after #284 and am merging.

I alwyas like to work with CMake occasionally to remind me how much I hate it.

There's always Autotools ;)

Thankfully I've never had to touch Autotools, but it scares me anyways.