CPU

Annotation used to tag a test, or suite of tests, as being CPU-intensive (i.e., consuming a lot of CPU time when it runs).

Note: This is actually an annotation defined in Java, not a Scala trait. It must be defined in Java instead of Scala so it will be accessible at runtime. It has been inserted into Scaladoc by pretending it is a trait.

If you wish to mark an entire suite of tests as being CPU-intensive, you can annotate the test class with @CPU, like this:

package org.scalatest.examples.flatspec.cpuall

import org.scalatest._
import tags.CPU

@CPU
class SetSpec extends FlatSpec {

  "An empty Set" should "have size 0" in {
    assert(Set.empty.size === 0)
  }

  it should "produce NoSuchElementException when head is invoked" in {
    intercept[NoSuchElementException] {
      Set.empty.head
    }
  }
}

When you mark a test class with a tag annotation, ScalaTest will mark each test defined in that class with that tag. Thus, marking the SetSpec in the above example with the @CPU tag annotation means that both tests in the class are CPU-intensive.

Another use case for @CPU is to mark test methods as CPU-intensive in traits Spec and fixture.Spec. Here's an example:

package org.scalatest.examples.spec.cpu

import org.scalatest._
import tags.CPU

class SetSpec extends Spec {

  @CPU def `an empty Set should have size 0` {
    assert(Set.empty.size === 0)
  }

  def `invoking head on an empty Set should produce NoSuchElementException` {
    intercept[NoSuchElementException] {
      Set.empty.head
    }
  }
}

The main use case of annotating a test or suite of tests is to select or deselect them during runs by supplying tags to include and/or exclude. For more information, see the relevant section in the documentation of object Runner.