Tuesday, April 17, 2012

Cucumber - my perspective

I have been using Cucumber (http://cukes.info/) at my current gig for about a year now. My initial reaction was that I absolutely hated it. It didn't seem to make sense for a programmer to write out tests (features) in plain English and then write out a bunch of regular expressions to turn that plain English into runnable code. What a palaver!

The other problem, is that the Cucumber tests were extremely fragile. Even making text and/or HTML changes would break things in lots of random places.

Anyways, as it turns out, I don't really hate Cucumber, I just hate the way it is implemented in my current gig. Here are some lessons I learnt on the way...

1) Features are not supposed to be written by programmers.
You can write features as a programmer, but you are not the intended audience. The reason why features are written in plain text is that they are supposed to be written by business owners. As a programmer though, you can use features to organize your thoughts in plain English.

For example

Given I am a shopper
When I add something to the cart
Then I should see it in the cart

2) Keep all implementation details out of the features.
The features are not for you (the programmer). They are for the business owners. You are just supposed to make them pass and use them as a guide.

3) Don't aim to re-use features
Testing is about the one place where DRY (Do not Repeat Yourself) does not apply. When you re-use the same tests/step definitions in multiple places, you are creating hidden dependencies between 2 sections of code which probably don't need to be there. A lot of developers also fall into this trap with CSS. As developers we are trained to look for similar behaviours and abstract them out into their own methods, but unless the business owner really decides the two features are linked, they should be kept separate. The one area where I don't agree with Cucumber is that all the step definitions are shared globally (I personally think each feature should have its own step definition file).

4) Features are not supposed to cover every possible edge case
Specs are used to make sure all your edge cases are covered. Features should only cover what is asked for by the business owners.

5) Do not tie your step definitions to HTML elements
This makes it impossible to do any redesign. It is a bit annoying that copy (or text) changes can break your tests, but at the end of the day, business owners are the ones who are in charge of copy and they should be aware that copy changes will come at a cost.

So at the end of the day, keep your features concise, don't reuse steps and write them like you are not a programmer and then you should be happy with Cucumber.

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