Fix upickle problem

build.sbt

@@ -16,7 +16,8 @@ libraryDependencies ++= Seq(
   "commons-io"             %  "commons-io"    % "2.11.0",
   "com.typesafe.akka"      %% "akka-actor"    % "2.6.20",
   "com.typesafe.akka"      %% "akka-testkit"  % "2.6.20" % "test",
-  "org.scalatest"          %% "scalatest"     % "3.2.14" % "test"
+  "org.scalatest"          %% "scalatest"     % "3.2.14" % "test",
+  "com.lihaoyi"            %% "upickle"       % "2.0.0"
 )
 
 import org.scoverage.coveralls.Imports.CoverallsKeys._

src/main/scala/org/scoverage/samples/CustomPicklers.scala

@@ -0,0 +1,25 @@
+package org.scoverage.samples
+
+import upickle._
+
+/**
+  * Json boilerplate.
+  * - Parse null and missing objects into scala Options
+  */
+object CustomPicklers {
+
+  object OptionPickler extends upickle.AttributeTagged {
+    override implicit def OptionWriter[T: Writer]: Writer[Option[T]] =
+      implicitly[Writer[T]].comap[Option[T]] {
+        case None    => null.asInstanceOf[T]
+        case Some(x) => x
+      }
+
+    override implicit def OptionReader[T: Reader]: Reader[Option[T]] = {
+      new Reader.Delegate[Any, Option[T]](implicitly[Reader[T]].map(Some(_))) {
+        override def visitNull(index: Int) = None
+      }
+    }
+  }
+
+}

src/main/scala/org/scoverage/samples/UpickleStuff.scala

@@ -0,0 +1,16 @@
+package org.scoverage.samples
+
+import org.scoverage.samples.CustomPicklers.OptionPickler.{
+  ReadWriter => RW,
+  macroRW
+}
+
+object UpickleStuff {
+  case class Person(
+      name: String
+  )
+
+  object Person {
+    implicit val rw: RW[Person] = macroRW
+  }
+}