> I don't quite get how any when/then could NOT be dependent upon previous givens.

Given I am called Bob
And I change my name to Steve
Then my name is not Bob

None of these steps are dependent on the ones previous to it, and can be reused elsewhere. The check for "my name is bob" can be used whether or not the previous step has been called. Your test won't pass, which is fine, but it will run and do exactly what it says. The step does what it says even if none of the others are used. It also means I can write a new test using bits from others without worrying about what's in the source code.

A test that looks like this:

Given I am a person
And I change my name
Then my name is different

Cannot be re-used. The "my name is different" can only be used if you know the ruby code underneath. "my name is different" may not do what you expect unless it comes after "I change my name".

What I meant with timing is the only way you can get around storing state is to have the "my name is different" watch for a change in the name, which brings in timing issues. I've seen both implementations used, and both caused problems (the timing one for obvious reasons).

> Not familiar with quickcheck, but I will look into it, thanks!

I thoroughly recommend it. The haskell version is probably the most advanced, but there are similar versions for most languages (and you can write your own, I had to for AS3). The idea is you express general properties about your system, and then it auto-generates thousands of examples (and if you have a nice library, automatically shrink failing cases for you). For example, the test above would be nicer as something like:

X is a string
Y is a string
X =/= Y

Given I am called X
And I change my name to Y
Then my name is not X
And my name is Y

Or something like that. This would then generate examples with no-length strings, crazy unicode characters, long strings, different mixings of RTL sections, etc. Much more likely to drive out bugs than a test for Bob and Steve.

Some more useful ones would look like this (the first is a test I've written before, but not in this format):

X is a number >= 1
Y is an interface element
Given I am on element Y
When I press Tab X times
And I press Shift-Tab X times
Then I am on element Y

A similar version for navigating in a website and pressing "back" to get back to where you were (to ensure you're not breaking the back button).

These are really simple, but powerful tests. I was most sold on the idea when I wrote this (not in this format, but this logic):

X is a positive integer
Y is a positive integer
INSTRUCTION is one of [addElement, removeElement(X), setFocus(X)]
MENU is an interface
When I perform Y INSTRUCTIONS
Then MENU has one focused item or no items at all

This then generated thousands of menus of each valid type (vertical, horizontal, grids, etc) and then called library functions to add or remove elements, or move focus. Millions of tests overall. I was using this as a test for my quickcheck implementation, and found it failed. If I set the focus, deleted all the elements and then added a single new one it wasn't focused.

When I fixed it, a unit test failed. We has previously specified that was to be the behaviour, but also specified that no matter what there would always be a focused element (if there were any elements at all). The general test drew out an inconsistency in our spec because we were forced to write general rules.

Mixing quickcheck and cucumber has been one of my "Some weekend I'll do it" projects for a couple of years now.