Richard Lawrence » Cuke4Nuke

Just Enough Regular Expressions for Cucumber

Richard Lawrence — Tue, 20 Jul 2010 21:38:50 +0000

Jon Archer wrote last week about how Cucumber makes knowledge of regular expressions important. He’s right: Regular expressions are the key to Cucumber’s flexibility. Well-crafted regular expressions let you reuse step definitions, avoiding duplication and keeping your tests maintainable. But even experienced developers find them mysterious and overwhelming.

Fortunately, you don’t need regular expressions like this one to wield the power of Cucumber:

(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])

In fact, if you use regular expressions like this in your step definitions, you’ve gone too far. (This regular expression, in case you’re wondering, matches the official spec for valid email addresses.)

As with most things, the 80/20 rule applies. There are a handful of useful patterns that are sufficient to make you a Cucumber power user.

Anchors

The regular expression I'm logged in matches I'm logged in and I'm logged in as an admin. To avoid ambiguous matches, use ^I'm logged in$.

The caret at the beginning anchors to the beginning of the string. The dollar at the end does the same with the end of the string. Use these with all your step definitions and you won’t have surprise matches.

Wildcards and quantifiers

Matching specific words is fine. But you often want flexibility to match a variety of strings. Here are some common patterns for non-exact matches.

`.*`	matches anything (or nothing), literally “any character (except a newline) 0 or more times”
`.+`	matches at least one of anything
`[0-9]` or `\d`	matches a series of digits (or nothing)
`[0-9]+` or `\d+`	matches one or more digits
`"[^\"]*"`	matches something (or nothing) in double quotes
`an?`	matches a or an (the question mark makes the n optional)

Capturing and not capturing

When you put part of a regular expression in parentheses, whatever it matches gets captured for use later. This is known as a “capture group.” In Cucumber, captured strings become step definition parameters. Typically, if you’re using a wildcard, you probably want to capture the matching value for use in your step definition. Here’s a Cuke4Nuke example,

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[Given(@"^I'm logged in as an? (.*)$")]
public void ImLoggedInAsA(string role)
{
// log in as the given role
}

If your step is Given I'm logged in as an admin, then the step definition gets passed "admin" for role.

Cuke4Nuke converts captured strings to the step definition parameter type, which is handy for step definitions like this:

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[Given(@"^I have (\d+) cukes$")]
public void IHaveNCukes(int cukeCount)
{
// set up the given number of cukes
}

The step Given I have 42 cukes means the step definition gets called with 42 (as an integer) for cukeCount.

Sometimes, you have to use parentheses to get a regular expression to work, but you don’t want to capture the match.

For example, suppose I want to be able to match both When I log in as an admin and Given I'm logged in as an admin. After all, both step definitions do the same thing. There’s no reason to have duplicated automation code in my step definitions simply because one is a Given and one is a When.

I might write something like this:

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[When(@"^(I'm logged|I log) in as an? (.*)$")]
public void LogInAs(string role)
{
// log in as the given role
}

The parentheses and pipe indicate a logical OR, just what I need to match two different strings.

This will fail to run, though. My regular expression is capturing two strings, but my step definition method only takes one. I need to designate the first group as non-capturing like this:

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[When(@"^(?:I'm logged|I log) in as an? (.*)$")]
public void LogInAs(string role)
{
// log in as the given role
}

Now, with the addition of ?: at the beginning of the group, it will perform as I expect.

By the way: You may be wondering how the attribute can be When and still match Given I'm logged in as an admin. It turns out that in Cuke4Nuke, just like in Cucumber for Ruby, it doesn’t matter whether you use Given, When, or Then to define a step definition. They’re all step definitions and are interchangeable. It’s fairly common for today’s When to be tomorrow’s Given, so this is a nice feature.

Just enough

This is only the tip of the regular expression iceberg. Here’s a book and website if you’re interested in going deeper. But for day-to-day work with Cucumber, anchors, simple wildcards and quantifiers, and capturing and non-capturing groups are all you need.

Debugging Cuke4Nuke Step Definitions

Richard Lawrence — Wed, 13 Jan 2010 02:52:51 +0000

At a client today, we were doing some tricky automation with WatiN (against Telerik controls) in Cuke4Nuke. We wanted to dig into what WatiN was finding in the browser. The obvious move was to fire up the debugger. But with Cuke4Nuke, this is trickier than you might think. The Cuke4Nuke gem includes a release build—no debug symbols. Plus, the process isn’t around long enough to attach to if you use the cuke4nuke executable. We probably could have figured it out, but it wasn’t worth the trouble.

Since we weren’t debugging the Cucumber side of things, we didn’t need all the Cucumber and Cuke4Nuke plumbing. We just needed to run the code using WatiN.

NUnit and Resharper to the rescue…Cuke4Nuke cares about Given, When, Then, Before, and After attributes on your methods. But that doesn’t mean those are the only attributes allowed.

We added a TestFixture attribute to the class. We put SetUp and TearDown attributes on the Before and After methods. We created a new method with a Test attribute that called the relevant step definition methods. Set a breakpoint, click the Resharper test icon and choose Debug, and next thing we knew we were debugging our way through the step definition code.

Next time you need to debug a tricky step definition, don’t bother trying to get Cuke4Nuke in the debugger. Just use your unit test framework to call your step definitions. It’s faster to set up and faster to run.

How to Remove Duplication in Cucumber Tests Using Scenario Outlines

Richard Lawrence — Mon, 04 Jan 2010 17:09:36 +0000

Gojko Adzic has a new blog post demonstrating the new table parameter support in Cuke4Nuke. Table parameters are an important part of Cucumber. They’re great for setting up data and asserting that lists are what you expect. But I use them much less often than the other kind of table in Cucumber, scenario outlines.

Scenario outlines are the solution to repetitive Given-When-Then scenarios. Extending the WatiN example in my previous screencast, we might find ourselves writing scenarios like:

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Scenario: Search - richard lawrence
Given I'm on the search page
When I search for "richard lawrence"
Then I should see "www.richardlawrence.info" in the results

Scenario: Search - pickaxe
Given I'm on the search page
When I search for "pickaxe"
Then I should see "www.ruby-doc.org/docs/ProgrammingRuby/" in the results

Scenario: Search - cuke4nuke
Given I'm on the search page
When I search for "cuke4nuke"
Then I should see "github.com/richardlawrence/Cuke4Nuke" in the results

This kind of repetition gets old fast, both to write and to read. Scenario outlines allow us to separate the structure of the test, which doesn’t change, from the data, which does. Here are the same scenarios refactored:

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Cucumber turns each example—each table row—into a concrete scenario before looking for matching step definitions in Cuke4Nuke, so nothing needs to change on the Cuke4Nuke side.

In most cases, I recommend starting with concrete scenarios and refactoring to scenario outlines once you have a few scenarios working with the correct step definitions.

The Latest on Cuke4Nuke

Richard Lawrence — Wed, 30 Dec 2009 17:42:38 +0000

This morning, I released version 0.3.0 of Cuke4Nuke. With this release, Cuke4Nuke supports almost everything you can do with Cucumber in Ruby or Java, making C# a first class language for Cucumber. (The only missing features are small things like tags on Before and After hooks and a richer Table object.) Check out the Cuke4Nuke wiki for instructions to install and get started with Cucumber in .NET. To see it in action, check out my screencast on Cuke4Nuke and WatiN.

Screencast: Testing Web Applications in .NET with Cuke4Nuke and WatiN

Richard Lawrence — Thu, 03 Dec 2009 15:53:41 +0000

Yesterday, I released Cuke4Nuke 0.2.2, which added WatiN compatibility and an example of how to use the two tools together. Here’s a short screencast in which I walk through the example:

Resources from the video:

The Cuke4Nuke Wiki with installation instructions
WatiN
Source code from the example
The new Ruby installer

Cuke4Nuke: Cucumber for .NET Teams

Richard Lawrence — Sun, 20 Sep 2009 00:16:38 +0000

Update: If you’ve just landed here, you could get the impression from this post that Cuke4Nuke doesn’t exist yet. It does. Check out this screencast showing what you can do with it as of early December 2009.

If you’ve read this blog for a while or talked with me about functional test tools, you’ve heard me talk about Cucumber. It’s my favorite ATDD tool because it’s so good at mapping stories and acceptance criteria to automated functional tests. Product Owners and BAs write acceptance criteria in natural language. Developers and testers unobtrusively automate tests for them. Anyone on the team can run the tests and see the current state of the system.

Here’s a simple example:

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Feature: Google search
In order to find things on the web
As a user
I want to search for web pages containing specific text

Scenario: Load search page
When I go to the search page
Then I should be on the search page

Scenario: Search
Given I'm on the search page
When I search for "richard lawrence"
Then I should see "www.richardlawrence.info" in the results

This reads almost exactly as I teach Product Owners to specify acceptance criteria. But it’s not just text. It’s a potentially automated test.

A developer or tester can come along and automate this test like so in Ruby:

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# assuming @google is an instance of a test DSL that wraps Watir, Selenium, etc.

When /^I search for "(.*)"$/ do |query|
@google.search_for query
end

Then /^I should see "(.*)" in the results$/ do |expected_text|
assert { @google.results_contain? expected_text }
end

# etc...

Each of the Given/When/Then calls is a step definition. When there’s a matching line in a Cucumber test, the step definition gets executed.

Recently, support was added for step definitions in Java via a project called Cuke4Duke:

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@When("I search for \"(*)\"")
public void search(String query) throws Exception
{
google.searchFor(query);
}

@Then("I should see \"(*)\" in the results")
public void checkResults(String expectedUrl)
{
assertThat(google.containsResult(expectedUrl), is(true));
}

Now, a Java team can use Cucumber without ever writing a line of Ruby.

Unfortunately, there’s nothing like this for .NET teams. Until now (or soon, anyway)…

AA-FTT and the Birth of Cuke4Nuke

Last month, I attended the Agile Alliance Functional Test Tool conference (AA-FTT for short). AA-FTT is an open space conference. I came with one goal: to get together with other people who want Cucumber for .NET and start making it happen. I wasn’t sure anyone else would be interested, so I was thrilled with the reaction.

Aslak Hellesøy introduced Cucumber for those in the group who hadn’t used it and then talked through the multiple language support he’d recently added to the tool. Then, we discussed ways to build .NET support. The obvious solution was to use IronRuby and Cucumber’s language support to handle C# step definitions. Matt Wynne downloaded the latest IronRuby and installed Cucumber on it. He kicked off a simple Cucumber example, and we waited. And waited. Some two minutes later, we had results from tests that take less than two seconds to run under the standard Ruby interpreter. In a process that values frequent, fast test runs, IronRuby was a non-starter. (If you want to try Cucumber under IronRuby, here are some instructions.)

So we discussed other options and settled on using a simple wire protocol for Cucumber to communicate to .NET out-of-process, similar to Slim in FitNesse. And here’s the best part: we started building it. Matt and I paired right there to start fleshing out the wire protocol (with Cucumber tests, naturally). Later in the week at Agile 2009, Matt and Aslak paired to build the Ruby side of the wire protocol, and Matt and I tackled the first bits of the .NET side. Last week, I got the skeleton of the .NET side working and up on GitHub. You can define simple steps in C#. Cucumber can ask the .NET wire server to tell it about the steps it has and to invoke them and return the pass/fail results.

About a week ago, Aslak announced the project on the Cucumber mailing list and recruited more contributors. Declan Whelan, Scott Ford, Åsmund Eldhuset, Anders Hammervold, Chris Kooken, and Steve Eley have already stepped up with ideas and code.

Getting Involed

How can you get involved? I’m glad you asked.

Join the mailing list.
Fork the GitHub repository and work on one of the features in the backlog.
Post a message to the mailing list to let us know what you’re working on. I’ll tag the ticket in the backlog with your GitHub username so we don’t duplicate effort. Prefix your message subject with [Cuke4Nuke].
Comment on tickets in the backlog.
Try using Cuke4Nuke as we develop it and give us feedback via the mailing list.
Shout encouragements in the comments here and on Twitter to let us know you care, even if you can’t contribute.