test_MagneticDipoleDipoleInteraction_ConstantIdenticalDipoles.py

from MPCDAnalysis.PairPotentials.MagneticDipoleDipoleInteraction_ConstantIdenticalDipoles \
    import MagneticDipoleDipoleInteraction_ConstantIdenticalDipoles as Potential
 
def test_constructor_get_parameters():
    from MPCDAnalysis.Vector3DReal import Vector3DReal
 
    import pytest
 
    orientation = Vector3DReal(1, 0, 0)
 
    with pytest.raises(TypeError):
        Potential([1], orientation)
 
    with pytest.raises(TypeError):
        Potential(1, [1, 0, 0])
 
 
    with pytest.raises(ValueError):
        Potential(-1, orientation)
 
    with pytest.raises(ValueError):
        Potential(1, orientation * 2)
 
 
    pot = Potential(2.5, orientation)
 
 
    assert isinstance(pot.getPrefactor(), float)
    assert pot.getPrefactor() == 2.5
 
    assert pot.getOrientation() == orientation
 
    orientation.x = 2
    assert pot.getOrientation() == Vector3DReal(1, 0, 0)
 
 
def test_getPotential():
    from MPCDAnalysis.Vector3DReal import Vector3DReal
 
    import pytest
 
    prefactor = 2.5
    orientation = Vector3DReal(0, 1, 0)
    pot = Potential(prefactor, orientation)
 
    def expected(r):
        ret = -prefactor
        ret *= 3 * orientation.dot(r.getNormalized()) ** 2 - 1
        ret /= r.getLength() ** 3
 
        return ret
 
 
    with pytest.raises(TypeError):
        pot.getPotential([1])
    with pytest.raises(TypeError):
        pot.getPotential(1)
 
    r = Vector3DReal(0, 0, 0)
    with pytest.raises(ValueError):
        pot.getPotential(r)
 
    for i in range(0, 100):
        r = Vector3DReal(-0.1 + i, i * 0.1, 2 * i)
 
        assert pot.getPotential(r) == pytest.approx(expected(r))