Scala mocking the behaviour - scala

Question

When I mock the particular object method is executing the actual behavior.
The expected output should be 10since I mocked the Calculate.add and returning the result as 10
trait Base {
def add (parm1:Int, parm2:Int): Int
def fetc ():Any
def compute(): Any
}
object Calculate extends Base {
def add(parm1:Int, parm2:Int):Int = {
fetc()
compute
}
def fetc ():Any = {
// Making some api1 call
}
def compute ():Any = {
// Making some api2 call
}
}
object Engine {
def execute():any{
Calculate.add(10, 20)
}
}
Test
class TestEngine extends MockFactory {
it should "compute" in {
val res1:Int = 10
val calculate: Base = stub[Base]
val data = (calculate.add _).when(10, 20).returns(res1);
Engine.execute() // ExpectedOutput should be 10(res1),Since the I mocked the add method and returning the 10 value. Should not call the Calculate object fetch, compute behaviour.
}
}

Answer 1

Though Calculate is mocked & add method has been stubbed, still the actual functionality of add will be executed, since in Engine.execute method Calculate object reference is used to access the add method also Calculate is itself an object, thus the actual code will be executed.
object Engine {
def execute():any{
Calculate.add(10, 20)
}
}
Simple solution to mocked calculate in Engine.execute could be instead of using Calculate object passed a base variable as method parameter.
object Engine {
def execute(base: Base): Int = {
base.add(10, 20)
}
}
class TestEngine extends MockFactory {
it should "compute" in {
val res1: Int = 10
val calculate: Base = stub[Base]
val data = (calculate.add _).when(10, 20).returns(res1);
//mocked_calculate
Engine.execute(mocked_calculate)
}
}