Checking the method calls to the manufactured object with default arguments

Question

Suppose I have this class:

class Defaults { def doSomething(regular: String, default: Option[String] = None) = { println(s"Doing something: $regular, $default") } } 

I want to verify that some other class calls the doSomething() method on the Defaults instance without passing a second argument:

 defaults.doSomething("abcd") // second argument is None implicitly 

However, the mocking Defaults class does not work correctly. Since the default values ​​for the method arguments are compiled as hidden methods in the same class, mock[Defaults] returns an object in which these hidden methods return null instead of None , so this test fails:

 class Test extends FreeSpec with ShouldMatchers with MockitoSugar { "Defaults" - { "should be called with default argument" in { val d = mock[Defaults] d.doSomething("abcd") verify(d).doSomething("abcd", None) } } } 

Mistake:

 Argument(s) are different! Wanted: defaults.doSomething("abcd", None); -> at defaults.Test$$anonfun$1$$anonfun$apply$mcV$sp$1.apply$mcV$sp(Test.scala:14) Actual invocation has different arguments: defaults.doSomething("abcd", null); -> at defaults.Test$$anonfun$1$$anonfun$apply$mcV$sp$1.apply$mcV$sp(Test.scala:12) 

The reason for this is clear, but is there a reasonable workaround? The only thing I see is to use spy() instead of mock() , but my mocking class contains many methods that I will have to mock explicitly in this case, and I don't want this.