Lightweight specs

The default Specification class mixes in most of specs2 features in order to make it very easy to write your first specifications without worrying too much about where the feature resides.

There at least 2 downsides to this approach:

• inside a Specification you get lots of inherited method names, encumbering the namespace
• many of the traits mixed-in the Specification class define implicit methods and those methods have a big impact on compilation times

It is thus possible to use another class, org.specs2.Spec (or org.specs2.mutable.Spec), which only provides the minimum number of implicits to create specifications.

With the Spec class you can create examples and expectations with simple matchers. For example:

class HelloWorldSpec extends Spec { def is = s2"""

 This is a specification to check the 'Hello world' string

 The 'Hello world' string should
   contain 11 characters                                         $e1
   start with 'Hello'                                            $e2
   end with 'world'                                              $e3
                                                                 """

 def e1 = "Hello world" must haveSize(11)
 def e2 = "Hello world" must startWith("Hello")
 def e3 = "Hello world" must endWith("world")
}

Or, for mutable specs:

class HelloWorldSpec extends mutable.Spec {

  addParagraph("This is a specification to check the 'Hello world' string")

 "The 'Hello world' string" should {
   "contain 11 characters" in {
     "Hello world" must haveSize(11)
   }
   "start with 'Hello'" in {
     "Hello world" must startWith("Hello")
   }
   "end with 'world'" in {
     "Hello world" must endWith("world")
   }
 }

}

If you compare those 2 specifications with the “HelloWorldSpec” examples using Specification you will notice some differences:

• you cannot write "Hello world" must have size(11)
• you cannot write "This is a specification to check the 'Hello world' string".txt to add some text to a mutable spec

But not all is lost! For each functionality you might want to use there is a trait which you can mix-in to get it.

Adding features

When creating expectations:

Feature	Trait	Comment
Use should for expectations	org.specs2.matcher.ShouldMatchers
Describe expectations with ==>	org.specs2.matcher.ExpectationsDescription
Describe expectations with aka and must	org.specs2.matcher.MustExpectations
Use list must have size(3)	org.specs2.matcher.TraversableMatchers	For each matcher you want to use after be/have/not, you need to mix-in the corresponding matchers trait
Use matchers in contain or beSome matchers	org.specs2.matcher.ValueChecks
Use ===, ==== to check for equality	org.specs2.matcher.TypedEqual
Create matchers from functions	org.specs2.matcher.MatchersCreation
Combine MatchResults with and/or	org.specs2.matcher.MatchResultsCombinators
Transform a Matcher[T] to Matcher[Seq[T]]	org.specs2.matcher.SequenceMatchersCreation
Use forall(values)(t => t must xxx)	org.specs2.matcher.SequenceMatchersCreation	You can combine all matchers features by using the org.specs2.matcher.MatchersImplicits trait
Set failed expectations as Pending	org.specs2.execute.PendingUntilFixed

When creating acceptance specifications

Feature	Trait	Comment
Interpolate anything else than a Result in a s2 string	org.specs2.specification.create.S2StringContext
Use “bang” examples: "example" ! ok	org.specs2.specification.dsl.ExampleDsl
Create and append Fragments with ^	org.specs2.specification.dsl.FragmentsDsl
Add arguments and a title to Fragments with ^	org.specs2.specification.dsl.SpecStructureDsl
Create a title with "A title".title"	org.specs2.specification.dsl.TitleDsl
Create references to other specifications	org.specs2.specification.dsl.ReferenceDsl
Create steps and actions	org.specs2.specification.dsl.ActionDsl
Use tags	org.specs2.specification.dsl.TagDsl	To use all of the Dsl traits use AcceptanceDsl

When creating mutable specifications

Feature	Trait	Comment
Use “bang” examples: "example" ! ok	org.specs2.specification.dsl.mutable.ExampleDsl
Create a title with "A title".title"	org.specs2.specification.dsl.mutable.TitleDsl
Set arguments	org.specs2.specification.dsl.mutable.ArgumentsDsl
Create references to other specifications	org.specs2.specification.dsl.mutable.ReferenceDsl
Create steps and actions	org.specs2.specification.dsl.mutable.ActionDsl
Add text and paragraphs	org.specs2.specification.dsl.mutable.TextDsl
Use tags	org.specs2.specification.dsl.mutable.TagDsl	To use all of the Dsl traits use MutableDsl