New feature for developwithpassion.specifications (nested contexts!!)
Written May 11, 2011 at 09:00 MDT Tagged tdd and c#
Technically this is a patch that I added to mspec, so it is there also!! Instead of talking about it, I will demonstrate with a bit of contrived example:
public abstract class concern : Observes<SimpleCalculator>
{
}
public class when_adding_two_numbers : concern
{
Establish c = () =>
{
connection = depends.on<IDbConnection>();
first_number = 1;
second_number = 2;
};
Because b = () =>
result = sut.add(first_number, second_number);
public class and_both_numbers_are_positive
{
It should_not_open_a_connection_to_the_database = () =>
connection.never_received(x => x.Open());
}
public class and_one_of_the_numbers_are_negative
{
Establish c = () => first_number = -2;
It should_open_a_connection_to_the_database = () =>
connection.received(x => x.Open());
}
It should_return_the_sum = () =>
result.ShouldEqual(first_number + second_number);
static IDbConnection connection;
static int result;
static int second_number;
static int first_number;
}
public class SimpleCalculator
{
IDbConnection connection;
public SimpleCalculator(IDbConnection connection)
{
this.connection = connection;
}
public int add(int number1, int number2)
{
if (number1 < 0 || number2 < 0) connection.Open();
return number1 + number2;
}
}
As you can see from this example. Nested contexts can be a useful tool when you want to have a different organizational mechanism for how you structure and separate concerns.
The root concern [when_adding_two_numbers] contains its own establish, because and it blocks.
Each of the nested contexts alters the setup as needed to test a different aspect of the component under a different context. And they also have their own it blocks to make their concern specific observations!!
For information, it is important to note that this is nothing more than a different organizational tool. You can express the exact same tests currently in mspec without needing to use nested contexts.