Why is this specs2 test using Mockito passing? - scala

Question

Suppose I had this interface and class:
abstract class SomeInterface{
def doSomething : Unit
}
class ClassBeingTested(interface : SomeInterface){
def doSomethingWithInterface : Unit = {
Unit
}
}
Note that the doSomethingWithInterface method does not actually do anything with the interface.
I create a test for it like this:
import org.specs2.mutable._
import org.specs2.mock._
import org.mockito.Matchers
import org.specs2.specification.Scope
trait TestEnvironment extends Scope with Mockito{
val interface = mock[SomeInterface]
val test = new ClassBeingTested(interface)
}
class ClassBeingTestedSpec extends Specification{
"The ClassBeingTested" should {
"#doSomethingWithInterface" in {
"calls the doSomething method of the given interface" in new TestEnvironment {
test.doSomethingWithInterface
there was one(interface).doSomething
}
}
}
}
This test passes. Why? Am I setting it up wrong?
When I get rid of the scope:
class ClassBeingTestedSpec extends Specification with Mockito{
"The ClassBeingTested" should {
"#doSomethingWithInterface" in {
"calls the doSomething method of the given interface" in {
val interface = mock[SomeInterface]
val test = new ClassBeingTested(interface)
test.doSomethingWithInterface
there was one(interface).doSomething
}
}
}
}
The test fails as expected:
[info] x calls the doSomething method of the given interface
[error] The mock was not called as expected:
[error] Wanted but not invoked:
[error] someInterface.doSomething();
What is the difference between these two tests? Why does the first one pass when it should fail? Is this not an intended use of Scopes?

Answer 1

When you mix-in the Mockito trait to another trait you can create expectations like there was one(interface).doSomething. If such an expression fails it only returns a Result, it doesn't throw an Exception. It then gets lost in a Scope because it is just a "pure" value inside the body of a trait.
However if you mix-in the Mockito trait to a mutable.Specification then an exception will be thrown on a failure. This is because the mutable.Specification class specifies that there should be ThrownExpectations by mixing in that trait.
So if you want to create a trait extending both Scope you can either:
create the trait from inside the specification and not have it extend Mockito:
class MySpec extends mutable.Specification with Mockito {
trait TestEnvironment extends Scope {
val interface = mock[SomeInterface]
val test = new ClassBeingTested(interface)
}
...
}
create trait and specification as you do, but mix-in org.specs2.execute.ThrownExpectations
trait TestEnvironment extends Scope with Mockito with ThrownExpectations {
val interface = mock[SomeInterface]
val test = new ClassBeingTested(interface)
}
class MySpec extends mutable.Specification with Mockito {
...
}