MbUnit–Hidden Gem

Row tests are fun. You can simulate various inputs with expected outputs and execute them all with a single observation (test). The problem for myself was always the fact that when this was done, the only way to accomplish it was to merge the logical because which operates on system under test behaviour and the observation itself (assertion). This leads to a slightly less readable code IMO.

[Row(“hello”, 5)]
[Row(“you”, 3)]
public void behaviour_and_observation(string value, int expected_number_of_letters)
{
	system_under_test.GetLenth(value).Should_be_equal_to(expected_number_of_letters);
}
Luckily, as pointed out by one of my ex-coworkers Dragosh, MbUnit has a way to assist with a specification that is trying to keep concerns separated. It’s called ParameterAttribute.

What specification does look like then?

[Header("Value", "ExpectedLength")]
[Row("hello", 5)]
[Row("you", 3)]
[Specification]
public class Some_specification : ContextSpecification
{
	[Parameter]
                 public string Value{ get; set; }
 
                 [Parameter]
                 public int ExpectedLength{ get; set; }
 
                 [Because]
                 protected void When_obtaining_length()
                 {
                          result = system_under_test.GetLength(Value);
                 }
 
                 [Observation]
      	 public void Should_get_proper_length()
                 {
                          result.Should_be_equal_to(ExpectedLength);
                 }
}

This is a trivial code, but with a bit more complex code the technique becomes really handy.

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