SpecFlow Tagging

It seems like SpecFlow tagging has been a theme in many of my recent posts. Its a very powerful concept and central to how I control test execution. Hopefully, this will give someone some inspiration. When I learned about tagging everything else seemed to click in regards to my understanding of the SpecFlow framework. Tagging was a bridge for me.

A Tag in SpecFlow is a way to mark features and scenarios. A Tag is an ampersand, @, and the text of the tag. If you tag a feature, it will apply to all feature’s scenarios and tagging a scenario will apply to all of the scenario’s steps.

Out the box SpecFlow implements the @ignore tag. This tag will generate an ignore attribute in your unit test framework. Although this is the only out the box tag, you can create as many tags as you like and there are a lot of cool things you can do with them.

SpecFlow uses tags to generate categories or attributes that can group and control test execution in the unit test framework that is driving your tests. Tags are also used control test execution outside the unit test framework in SpecFlow’s event bindings and scoped bindings. You also have access to tags in your test code through the ScenaroContext.Current.ScenarioInfo.Tags property.

Another benefit of tagging is that the tags can be targeted from the command line. I can run my tests from the command line and indicate what tags I want to run. This means I can control testing on my continuous integration server.

As you can see, tags are very powerful indeed in shaping the execution of your tests. Below I will explain how I am currently using tags in a standardized way in my test framework. My tagging scheme is still a work in progress and I am honing in on the proper balance of tags that will allow good control of the tests without creating accidental complexity and a maintenance nightmare.

In the feature file for UI tests I have the following tags:

  • Test Type – in our environment we run Unit, Integration, Smoke, and Functional tests, in order of size and speed of the tests. A feature definition should only include one test type tag, but there can be situations where a Functional could include lower tests, but no other test types should be mixed. So you could have @Smoke and @Functional, but not @Smoke and @Unit.
  • Namespace – each C# namespace segment is a tag. For example, if I have a namespace of Foo.Bar then my tags would be @Foo @Bar
  • SUT – the system under test is the class or name of the page or control
  • Ticket Number – the ticket number that the feature was created or changed on (e.g. @OFT11294). We prefix the number to better identify this tag as a ticket.
  • Requirement – this is a reference to the feature section in the business requirements document that the feature spec is based on (e.g. @Rq4.4.1.5). We prefix the number to better identify this tag as a requirement.

With the above examples our feature definition would look like this:

@Integration @Foo @Bar @OFT11294 @Rq4.4.1
Feature: Awesome  Thing-a-ma-gig

This allows me to target the running of tests for different namespaces, test types, SUT, ticket numbers, requirements or any combination of them. When a developer deploys changes for a ticket, I can just run the tickets that target the ticket. This is huge in decreasing the feedback cycle for tests. Instead of having to run all the tests, and this could be hours, we can run a subset and get a quicker response on the outcome of the tests.

At the scenario level we want to tag the system under test (SUT). This allows us to run test for a particular  SUT, but it also gives us the flexibility of hooking behavior into our test runs. Say I want to instantiate a specific class for each scenario, if I did a BeforeFeature Hook with no tagging it would apply to every scenario in the test assembly because SpecFlow Hooks are global. With tagging, it will run for scenarios with matching tags.

…Feature File

@Integration @Foo @Bar @OFT11294 @Rq4.4.1
Feature: Awesome  Thing-a-ma-gig

@Thingamagig @Rq4.4.1.5
Scenario: Awesome Thing-a-ma-gig works

…Step Class

[BeforeScenario(“Thingamagig“)]
public static void ScenarioSetup()
{
sut = new Thingamagig();
}

We have the @Ignore tag that we can apply to features and scenarios to signal to the test runner to not run the tagged item. There is also a @Manual tag that functions like the @Ignore tag for features and scenarios that have to be ran manually. I did some custom logic to filter the @Manual tag, but you can find a simple way to do it on this short post on SpecFlow Manual Testing.

In my test framework I have fine grained control of test execution through a little helper class I created. I won’t bore you with all of the code, but basically I use a scoped BeforeFeature binding to call a bit of code that decides if the feature or scenario should be ran or not. Yes this kind of duplicates what SpecFlow and the unit test framework already does, but I am a control freak. This code is dependent on SpecFlow and NUnit.Framework.

if (IgnoreFeature(FeatureContext.Current.FeatureInfo.Tags))
{
Assert.Ignore();
return;
}

The IgnoreFeature() method will get the tags to run or ignore from a configuration file. If the tag in FeatureContext.Current.FeatureInfo.Tags matches an ignore tag from configuration it will return true. If the tag matches a run tag it will return false. We also include matching to ignore the @Ignore and @Manual, even though there is already support for @Ignore. This same concept applies to scenarios and ScenarioContext.Current.ScenarioInfo.Tags that are evaluated in a global BeforeScenario binding. In the example above I am using Assert.Ignore() to ignore the test. As you probably know Ignore in unit test frameworks is usually just an exception it throws to immediately fail the test. In my actual test framework, I replace Assert.Ignore() with my own custom exception that I throw that will allow the ignored tags to be logged.

With this method of tagged based ignoring using a configuration file, we could add a tag for environment to control test execution by environment. I say this because I have seen many questions about controlling tests by environment. The point is, there are many ways to use tags and the way I use them is just one way. You can tag how you want and there are some great posts out there to give you inspiration on how to use them for your situation.

Pros and Cons of my SpecFlow Tagging Implementation

Pros:

  • Fine grained control of test execution.
  • Controlling tests through configuration and command line execution.
  • Tractability of tests to business requirements and work tickets.

Cons:

  • Tags have no IntelliSence in VisualStudio.
  • Tags are static strings so spelling is an issue.
  • When a namespace or SUT name changes we have to remember to change the name in the feature and step files.
  • Tags can get messy and complicating, especially when test covers multiple tickets or features.

Ref:

3 comments

  1. Pingback: Agile Browser Based Testing with SpecFlow | Decoupled Logic

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