Improve test coverage. #58

Job	Run time
posix (Collect coverage special_fun, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, special_...	16m 27s
posix (Collect coverage special_fun, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, special_...	16m 22s
posix (Collect coverage distribution_tests, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, d...	7m 0s
posix (Collect coverage distribution_tests, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, d...	7m 0s
posix (Collect coverage mp, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, mp)	3m 29s
posix (Collect coverage mp, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, mp)	3m 29s
posix (Collect coverage misc, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, misc)	9m 56s
posix (Collect coverage misc, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, misc)	9m 27s
posix (Collect coverage quadrature, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, quadrature)	15m 26s
posix (Collect coverage quadrature, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, quadrature)	15m 2s
posix (Collect coverage interpolators, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, interp...	31m 44s
posix (Collect coverage interpolators, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, interp...	31m 44s
posix (Collect coverage autodiff, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, autodiff)	6m 8s
posix (Collect coverage autodiff, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, autodiff)	6m 8s
	2h 59m 22s

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