[TEST] Refactor api tests

[Irallia]

Some refactoring for #168 .

[codecov]

Codecov Report

Merging #169 (9a7e65d) into master (d14e155) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #169   +/-   ##
=======================================
  Coverage   96.48%   96.48%           
=======================================
  Files          19       19           
  Lines         797      797           
=======================================
  Hits          769      769           
  Misses         28       28           

Impacted Files	Coverage Δ
src/variant_detection/variant_detection.cpp	93.97% <ø> (ø)

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[SGSSGene]

There might be subtle problem with gVerbose = true. By default it is initialized to false. Depending on the unit test order, it might be set to true by a previous unittest.
So it is necessary to reset it to false.
I think this could be a great use case of the use of a scope guard (Idea taken from here https://stackoverflow.com/questions/28729545/abusing-c11-unique-ptr-to-execute-code-upon-leaving-the-scope):
By implementing a scope guard function:

template<class F> auto scope_guard(F&& f) {
    return std::unique_ptr<void, std::decay<F>::type>{(void*)1, std::forward<F>(f)};
}

You can now protect your code by writting:

TEST(...) {
    auto verboseGuard = scope_guard([]{gVerbose = false; });
    gVerbose = true;
    ....
}

Or you define even a help construct for that:

template<class F> auto scope_guard(F&& f) {
    return std::unique_ptr<void, std::decay<F>::type>{(void*)1, std::forward<F>(f)};
}
auto guard_verbose (bool verbose) {
    auto lastState = gVerbose;
    gVerbose = verbose;
    return scope_guard([=]{gVerbose = lastState; });
}

This would allow you to write:

TEST(...) {
    auto verboseGuard = verbose_guard(true); // will reset back to the original state, after leaving this scope
    ....
}

[SGSSGene]

Looks good to me :-)

[joergi-w]

Suggested change

	// Lambda is being executed when the scope of the unique_ptr is being left
	// Lambda is executed when the scope of the unique_ptr ends

[joergi-w]

#include <vector> is missing

[joergi-w]

This is printed on each test execution – is this intended (even if print_compare_junction_vectors is just a comment)? The same below for the second example.

[Irallia]

Yes, because it splits the different examples. I think a few prints give a little more clarity, as there are other printouts while executing the single tests.