diff --git a/build.sbt b/build.sbt
index 5f182d7..83c1d76 100644
--- a/build.sbt
+++ b/build.sbt
@@ -47,7 +47,6 @@ lazy val scalacheck = project
   )
   .dependsOn(core)
 
-
 lazy val playJson = project
   .in(file("modules/play-json"))
   .settings(
@@ -58,7 +57,6 @@ lazy val playJson = project
   )
   .dependsOn(core)
 
-
 lazy val tests = project
   .in(file("modules/tests"))
   .settings(
diff --git a/modules/play-json/src/test/scala/Main.scala b/modules/play-json/src/test/scala/Main.scala
deleted file mode 100644
index c3eb187..0000000
--- a/modules/play-json/src/test/scala/Main.scala
+++ /dev/null
@@ -1,27 +0,0 @@
-package scalaz
-
-package schema
-
-package play.json
-
-import scalaz.schema.TestMain
-import testz.Harness
-import testz.runner.Runner
-
-import scala.concurrent.Await
-import scala.concurrent.ExecutionContext.global
-import scala.concurrent.duration.Duration
-
-object Main extends TestMain {
-
-  def tests[T](harness: Harness[T]): List[(String, T)] =
-    List(
-      ("Examples", PlayJsonExamples.tests(harness))
-    )
-
-  def main(args: Array[String]): Unit = {
-    val result = Await.result(Runner(suites(harness), global), Duration.Inf)
-
-    if (result.failed) throw new Exception("some tests failed")
-  }
-}
diff --git a/modules/tests/src/main/scala/Main.scala b/modules/tests/src/main/scala/Main.scala
index 3150eae..3db9df3 100644
--- a/modules/tests/src/main/scala/Main.scala
+++ b/modules/tests/src/main/scala/Main.scala
@@ -45,7 +45,8 @@ object Main {
       ("Examples", SchemaModuleExamples.tests(harness)),
       ("JSON", JsonExamples.tests(harness)),
       ("Scalacheck generators", GenModuleExamples.tests(harness)),
-      ("Generic Show interpreter", ShowExamples.tests(harness))
+      ("Generic Show interpreter", ShowExamples.tests(harness)),
+      ("Play-JSON codecs", PlayJsonExamples.tests(harness))
     )
 
   def main(args: Array[String]): Unit = {
diff --git a/modules/play-json/src/test/scala/PlayJsonExamples.scala b/modules/tests/src/main/scala/PlayJsonExamples.scala
similarity index 69%
rename from modules/play-json/src/test/scala/PlayJsonExamples.scala
rename to modules/tests/src/main/scala/PlayJsonExamples.scala
index bdddcf0..ea09587 100644
--- a/modules/play-json/src/test/scala/PlayJsonExamples.scala
+++ b/modules/tests/src/main/scala/PlayJsonExamples.scala
@@ -2,17 +2,16 @@ package scalaz
 
 package schema
 
-package play.json
+package tests
 
 import testz._
 import _root_.play.api.libs.json._
-import monocle.Iso
 import org.scalacheck._, Prop._, Arbitrary._
 
 object PlayJsonExamples {
 
-  val jsonModule = new PlayJsonModule[JsonSchema.type] with scalacheck.GenModule[JsonSchema.type] {
-    val R = JsonSchema
+  val module = new TestModule with play.json.PlayJsonModule[JsonSchema.type]
+  with scalacheck.GenModule[JsonSchema.type] {
 
     implicit val primToGenNT = new (JsonSchema.Prim ~> Gen) {
       override def apply[A](prim: JsonSchema.Prim[A]): Gen[A] = prim match {
@@ -52,7 +51,7 @@ object PlayJsonExamples {
   def tests[T](harness: Harness[T]): T = {
     import harness._
     import Schema._
-    import jsonModule._
+    import module._
     import JsonSchema._
 
     section("play-json codecs")(
@@ -67,34 +66,6 @@ object PlayJsonExamples {
         )
       },
       test("Derived `Reads` and `Writes` for a given schema should be symmetrical") { () =>
-        val user = record(
-          "active" -*>: prim(JsonSchema.JsonBool),
-          Iso[Boolean, User](User.apply)(_.active)
-        )
-
-        val admin = record(
-          "rights" -*>: seq(prim(JsonSchema.JsonString)),
-          Iso[List[String], Admin](Admin.apply)(_.rights)
-        )
-
-        val person = record(
-          "name" -*>: prim(JsonSchema.JsonString) :*:
-            "role" -*>: optional(
-            union(
-              "user" -+>: user :+:
-                "admin" -+>: admin,
-              Iso[User \/ Admin, Role] {
-                case -\/(u) => u
-                case \/-(a) => a
-              } {
-                case u @ User(_)  => -\/(u)
-                case a @ Admin(_) => \/-(a)
-              }
-            )
-          ),
-          Iso[(String, Option[Role]), Person]((Person.apply _).tupled)(p => (p.name, p.role))
-        )
-
         implicit val personGen = Arbitrary(person.to[Gen])
 
         val reader = person.to[Reads]