def test_is_null_throws_error_on_invalid_value(value: str):
"""
Tests that the `is_null()` method does not throw an ArgumentError
when it is supplied with an invalid value.
"""
# Arrange
validator = StringValidator(value, 'value')
# Assert
with pytest.raises(ArgumentNullError):
# Act
validator.is_null()
def test_is_null_throws_error_on_whitespace_value():
"""
Tests that the `is_null()` method throws an ArgumentError
when it is supplied with a whitespace value.
"""
# Arrange
value = WHITESPACE_STRING
validator = StringValidator(value, 'value')
# Assert
with pytest.raises(ArgumentNullError):
# Act
validator.is_null()
def test_is_null_accepts_null_value():
"""
Tests that the `is_null()` method does not throw an ArgumentError
when it is supplied with a None (Null) value.
"""
# Arrange
value = None
validator = StringValidator(value, 'value')
# Act
try:
validator.is_null()
# Assert
except ArgumentNullError:
pytest.fail(f'`{value}` should have been None (Null), but an error occurred instead.')
def test_is_null_returns_validator_self():
"""
Tests if the `is_null()` validator method returns itself after the validation is performed,
so that additional validations can be performed.
"""
# Arrange
value = None
validator = StringValidator(value, 'value')
# Act
validator_returned = validator.is_null()
# Assert
assert validator_returned is validator