Scala Programming Projects

org.scalactic.Equality

The Equality type class is used by ScalaTest unit tests whenever you write assertions, such as the following:

actual shouldBe expectedactual should === (expected)

Most of the time, you will not have to worry about it; the default instance compares types by using the equals method. However, whenever you compare double values or classes that contain double attributes, it becomes necessary to provide a different Equality instance.

Consider the following unit test:

class EqualitySpec extends WordSpec with Matchers with TypeCheckedTripleEquals{
  "Equality" should {
    "allow to compare two Doubles with a tolerance" in {
      1.6 + 1.8 should === (3.4)
    }
  }
}

This test should pass, right? Wrong! Try to run it; the assertion fails, ...