Value Members

1.  object ArbitrarySection extends Checkers with Matchers with Section

   There is a special generator, org.scalacheck.Arbitrary.arbitrary, which generates arbitrary values of any supported type.

   The arbitrary Generator

   There is a special generator, org.scalacheck.Arbitrary.arbitrary, which generates arbitrary values of any supported type.

   val evenInteger = Arbitrary.arbitrary[Int] suchThat (_ % 2 == 0)
   val squares = for {
     xs <- Arbitrary.arbitrary[List[Int]]
   } yield xs.map(x => x*x)

   The arbitrary generator is the generator used by ScalaCheck when it generates values for property parameters. Most of the times, you have to supply the type of the value to arbitrary, like above, since Scala often can't infer the type automatically. You can use arbitrary for any type that has an implicit Arbitrary instance. As mentioned earlier, ScalaCheck has default support for common types, but it is also possible to define your own implicit Arbitrary instances for unsupported types. See the following implicit Arbitrary definition for booleans, that comes from the ScalaCheck implementation.

   implicit lazy val arbBool: Arbitrary[Boolean] = Arbitrary(oneOf(true, false))

2.  object GeneratorsHelper
3.  object GeneratorsSection extends Checkers with Matchers with Section

   Generators are responsible for generating test data in ScalaCheck, and are represented by the org.scalacheck.Gen class.

   Generators are responsible for generating test data in ScalaCheck, and are represented by the org.scalacheck.Gen class. ou need to know how to use this class if you want ScalaCheck to generate data of types that are not supported by default, or if you want to use the forAll method mentioned above, to state properties about a specific subset of a type. In the Gen object, there are several methods for creating new and modifying existing generators. We will show how to use some of them in this section. For a more complete reference of what is available, please see the API scaladoc.

   A generator can be seen simply as a function that takes some generation parameters, and (maybe) returns a generated value. That is, the type Gen[T] may be thought of as a function of type Gen.Params => Option[T]. However, the Gen class contains additional methods to make it possible to map generators, use them in for-comprehensions and so on. Conceptually, though, you should think of generators simply as functions, and the combinators in the Gen object can be used to create or modify the behaviour of such generator functions.

4.  object PropertiesSection extends Checkers with Matchers with Section

   A property is the testable unit in ScalaCheck, and is represented by the org.scalacheck.Prop class.

   A property is the testable unit in ScalaCheck, and is represented by the org.scalacheck.Prop class. There are several ways to create properties in ScalaCheck, one of them is to use the org.scalacheck.Prop.forAll method like in the example below.

   scala> val propConcatLists = forAll { (l1: List[Int], l2: List[Int]) =>
     l1.size + l2.size == (l1 ::: l2).size }

   We can use the check method to test it:

   scala> propConcatLists.check
   + OK, passed 100 tests.

   OK, that seemed alright. Now, we'll define another property.

   scala> val propSqrt = forAll { (n: Int) => scala.math.sqrt(n*n) == n }

   And check it:

   scala> propSqrt.check
   ! Falsified after 2 passed tests.
   > ARG_0: -1
   > ARG_0_ORIGINAL: -488187735

   Not surprisingly, the property doesn't hold. The argument -1 falsifies it. You can also see that the argument -488187735 falsifies the property. That was the first argument ScalaCheck found, and it was then simplified to -1.

   The forAll method creates universally quantified properties directly, but it is also possible to create new properties by combining other properties, or to use any of the specialised methods in the org.scalacheck.Prop object.

5.  object ScalacheckDatetimeSection extends Checkers with Matchers with Section

   scalacheck-datetime is a library for helping use datetime libraries with ScalaCheck

   scalacheck-datetime is a library for helping use datetime libraries with ScalaCheck

   The motivation behind this library is to provide a simple, easy way to provide generated date and time instances that are useful to your own domain.

   For SBT, you can add the dependency to your project’s build file:

   resolvers += Resolver.sonatypeRepo("releases")
   
   "com.47deg" %% "scalacheck-toolbox-datetime" % "0.3.1" % "test"

   Please, visit the homepage for more information

6.  object ScalacheckLibrary extends Library

   ScalaCheck is a tool for testing Scala and Java programs, based on property specifications and automatic test data generation.