def test_is_empty_zero_size(self) -> None:
"""
Test that is_empty is True when there is a matrix set but its size is 0.
"""
e = MatrixDataElement(())
assert isinstance(e._matrix, np.ndarray)
assert e.is_empty() is True
def test_is_empty_false(self) -> None:
"""
Test that is_empty is False when there is valid matrix data set.
"""
e = MatrixDataElement((1,))
assert e.is_empty() is False
def test_is_empty_None(self) -> None:
"""
Test that is_empty is True when there is no matrix set.
"""
e = MatrixDataElement(None)
assert e.is_empty() is True