Reorganising the MPI code and adding a default main() entry to the MPI

[jokervTv]

Dear, sir

• Fixed linker error by restructuring the code when tried to use cmake to integrate doctest with mpi.
• Standardising the style of the code using project .clang-format.
• Used 'Include Guards' instead of #program once to improve compatibility.
• Added macro DOCTEST_CONFIG_IMPLEMENT_WITH_MPI_MAIN to provide a default main entry for mpi tests.
• Markdown documentation has also been updated.

Thanks for open sourcing this useful library.

[codecov]

Codecov Report

Merging #677 (b70116e) into dev (b7c21ec) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##              dev     #677   +/-   ##
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  Coverage   92.19%   92.19%           
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  Files           2        2           
  Lines        2127     2127           
=======================================
  Hits         1961     1961           
  Misses        166      166           

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[Saalvage]

This is a huge PR, I hope you understand that it will likely take some time to be merged.

@philbucher Do you think you will have the time to take a look at this anytime soon?

[philbucher]

First of all thanks for your contributions, I like to see that the MPI-version of doctest gains traction!

A few general comments. It seems like this PR does multiple things. Especially the reformatting makes it very hard to review. If possible, can you please make a separate PR for them to simplify the review of this one? You are making sensible changes to the code which need to be well understood, since we had problems not long ago. (@Saalvage what is the current way of doing code-formatting? Is it part of the CI?)

@BerengerBerthoul @starintheuniverse you also use this, can you please also have a look?

[philbucher]

Including source files is usually not recommend
Can you please explain your reasoning?

[jokervTv]

the mpi.cpp is a test file with DOCTEST_CONFIG_IMPLEMENT_WITH_MPI_MAIN in same folder, using it to test the mpi function with default main(). I think this approach allows for new tests to be simply added later, just need once in mpi.cpp.

is it a good way to change the file name or add new header file here?

[jokervTv]

Thank you for your comments.
I need some time to think about how to separate PR.

[starintheuniverse]

Agreed, it's great to have more eyes and hands on the MPI extension!
I will also try to take a closer look at this over the weekend.

@jokervTv

• Fixed linker error by restructuring the code when tried to use cmake to integrate doctest with mpi.

as you are organizing/annotating the PR, I think it would be helpful to describe your build system and the linker error in a bit more detail to make it reproducible. I didn't run into issues with CMake before so I am curious.

[jokervTv]

Dear Sir,

I have separated(in order) the PR to

• Use include guards #679 , instead of #program once to improve compatibility.
• Optimized code structure #680 , the reason is here Optimized code structure #680 (comment), @starintheuniverse
• Added macro to provide a default main entry for mpi tests. #681
• Update testing and documentation #682

I had delete Standardising the style of the code using project .clang-format, this may be better to review.
And how to handle this PR, Just close?