def test_gamma():
"""
This test checks that the gamma function correctly calculates the Lorenzt factor. Using the
approximation function accounts for the floating point error. It will also test that if a
singularity occurs (particle's speed equal to the speed of light) or if a math domain error occurs
(particle's velocity is greater than the speed of light), the correct error is raised.
"""
calculated_value = 1.342384701 # calculated by hand using c = 299792458 [ms^(-1)]
proton = Particle('proton', const.m_p, [0,0,0], [200000000,0,0])
assert calculated_value == pytest.approx(proton.gamma())
proton.velocity = np.array([1.1*const.c,0,0])
with pytest.raises(ValueError):
proton.gamma()
proton.velocity = np.array([const.c,0,0])
with pytest.raises(ZeroDivisionError):
proton.gamma()
