I just published ScalaMock 4.0.0 to Maven Central (JCenter should sync up soon).
This is mostly a bugfix release, but also builds for Scala 2.13.0-M1 and includes one new feature:
Argument matchers for fail-fast assertion style testing
4.0.0 is still compatible with ScalaMock 3.x, but the project structure has changed a bit, and there is just one dependency for both ScalaTest and Specs2:
libraryDependencies += “org.scalamock” %% “scalamock” % “4.0.0” % Test
libraryDependencies += “org.scalatest” %% “scalatest” % “3.0.4” % Test
Release notes: https://github.com/paulbutcher/ScalaMock/releases/tag/v4.0.0