mrdziuban / scalacheck-magnolia

Scalacheck Arbitrary derivation using magnolia

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scalacheck-magnolia performs generic derivation of scalacheck Arbitrary instances for product and sum types, i.e. case classes and ADTs, using Magnolia. Much of the code was inspired by scalacheck-shapeless, which I've found to work reliably, but cause huge compile time increases, especially for deeply nested case classes.


Add to your build.sbt:

libraryDependencies += "com.mrdziuban" %% "scalacheck-magnolia" % "0.0.2"

This will pull in scalacheck 1.14.0 and magnolia 0.10.0.

To materialize Arbitrary instances for your case classes or sealed traits, import com.mrdziuban.ScalacheckMagnolia._. Magnolia can derive Arbitrary instances for case classes

import com.mrdziuban.ScalacheckMagnolia._
import org.scalacheck.Arbitrary

case class Test(i: Int, b: Boolean, s: String)


as well as for sealed traits

sealed trait Foo
case object Bar extends Foo
case class Baz(s: String) extends Foo


It can be used in scalacheck property tests like so:

import org.scalacheck.Prop.forAll

case class Test(i: Int, b: Boolean, s: String)

forAll((t: Test) => true /* check some properties of Test */)


Released under the Apache 2.0 license. See the LICENSE file for more details.