Troubles w/ onCall in ScalaMock 3.x proxy mocks

OnCallTest.scala

package com.example

import org.scalatest.FunSuite
import org.scalamock.scalatest.MockFactory
import org.scalamock.proxy.ProxyMockFactory

class OnCallTest extends FunSuite with ProxyMockFactory with MockFactory {
  trait OnCallTrait {
    def foo (a: Int, b: Double)
  }

  test("onCall is happy with just Product") {
    val foo = super[ProxyMockFactory].mock[OnCallTrait]
    foo.expects('foo)(*,*).onCall { x: Product => "foo" }
    foo.foo(1, 2.0)
  }

  test("onCall with Product2 won't compile") {
    val foo = super[ProxyMockFactory].mock[OnCallTrait]
    // foo.expects('foo)(*,*).onCall { x: Product2[Int, Double] => "foo" }
    // required: Product => Any, found: Product2[Int, Double] => String
    // foo.foo(1, 2.0)
  }

  test("onCall with Tuple won't compile") {
    val foo = super[ProxyMockFactory].mock[OnCallTrait]
    // foo.expects('foo)(*,*).onCall { (a: Int, b: Double) => "foo" }
    // required: Product => Any, found: (Int, Double) => String
    // foo.foo(1, 2.0)
  }
}