def test_raise_exception_when_inverse_of_a_noninvertible_matrix():
A = Matrix(-4, 2, -2, -3,
9, 6, 2, 6,
0, -5, 1, -5,
0, 0, 0, 0)
assert not A.is_invertible()
with pytest.raises(NonInvertibleMatrixError):
A.inverse()
def testing_a_noninvertible_matrix_for_invertibility():
# Given
A = Matrix(-4, 2, -2, -3,
9, 6, 2, 6,
0, -5, 1, -5,
0, 0, 0, 0)
# Then
assert A.determinant() == 0
assert not A.is_invertible()
def testing_an_invertible_matrix_for_invertibility():
# Given
A = Matrix(6, 4, 4, 4,
5, 5, 7, 6,
4, -9, 3, -7,
9, 1, 7, -6)
# Then
assert A.determinant() == -2120
assert A.is_invertible()