could not find implicit value for evidence parameter of type org.scalacheck.Arbitrary

2
votes

I was trying to use a method called random with the following signature:

def random[T: WeakTypeTag: Arbitrary]: T

On a case class named Checking but I get this :

could not find implicit value for evidence parameter of type org.scalacheck.Arbitrary[com.organization.lambda.Checking]

I know this is due to some issues with context bounds, but I can't get my head around that and understand what has to be done.

1
scalacontext-bound

1 Answers

3
votes

Do you use random-data-generator-magnolia?

If so, you should specify implicit value for Arbitrary[Checking] case class.

Example from test source:

implicit val arbitraryPerson: Arbitrary[Person] = Arbitrary {
  for {
    name <- Gen.oneOf("Daniela", "John", "Martin", "Marco")
    age <- Gen.choose(0, 100)
  } yield Person(name, age)
}

val instance = random[Person]

Person is: 

case class Person(name: String, age: Int)