'Test for the matrix_frac atom.'

def test_matrix_frac(self):

    atom = matrix_frac(self.x, self.A)
    self.assertEqual(atom.size, (1, 1))
    self.assertEqual(atom.curvature, s.CONVEX)
    with self.assertRaises(Exception) as cm:
        matrix_frac(self.x, self.C)
    self.assertEqual(str(cm.exception), 'The    second    argument    to    matrix_frac    must    be    a    square    matrix.')
    with self.assertRaises(Exception) as cm:
        matrix_frac(Variable(3), self.A)
    self.assertEqual(str(cm.exception), 'The    arguments    to    matrix_frac    have    incompatible    dimensions.')
