feat: implement interop for newtype

build.sbt

@@ -79,6 +79,8 @@ lazy val zioJsonRoot = project
     zioJsonInteropScalaz7x.js,
     zioJsonInteropScalaz7x.jvm,
     zioJsonInteropScalaz7x.native,
+    zioJsonInteropNewtype.js,
+    zioJsonInteropNewtype.jvm,
     zioJsonGolden
   )
 
@@ -357,6 +359,22 @@ lazy val zioJsonInteropRefined = crossProject(JSPlatform, JVMPlatform, NativePla
   )
   .enablePlugins(BuildInfoPlugin)
 
+lazy val zioJsonInteropNewtype = crossProject(JSPlatform, JVMPlatform)
+  .in(file("zio-json-interop-newtype"))
+  .dependsOn(zioJson)
+  .settings(stdSettings("zio-json-interop-newtype"))
+  .settings(buildInfoSettings("zio.json.interop.newtype"))
+  .settings(macroExpansionSettings)
+  .settings(
+    libraryDependencies ++= Seq(
+      "io.estatico" %%% "newtype"      % "0.4.4",
+      "dev.zio"     %%% "zio-test"     % zioVersion % "test",
+      "dev.zio"     %%% "zio-test-sbt" % zioVersion % "test"
+    ),
+    testFrameworks += new TestFramework("zio.test.sbt.ZTestFramework")
+  )
+  .enablePlugins(BuildInfoPlugin)
+
 lazy val zioJsonInteropScalaz7x = crossProject(JSPlatform, JVMPlatform, NativePlatform)
   .in(file("zio-json-interop-scalaz7x"))
   .dependsOn(zioJson)
@@ -398,6 +416,7 @@ lazy val docs = project
       zioJsonInteropHttp4s,
       zioJsonInteropRefined.jvm,
       zioJsonInteropScalaz7x.jvm,
+      zioJsonInteropNewtype.jvm,
       zioJsonGolden
     ),
     readmeAcknowledgement :=

zio-json-interop-newtype/shared/src/main/scala/zio/json/interop/newtype/package.scala

@@ -0,0 +1,19 @@
+package zio.json.interop
+
+import io.estatico.newtype.Coercible
+import io.estatico.newtype.ops._
+import zio.json.{ JsonDecoder, JsonEncoder, JsonFieldDecoder, JsonFieldEncoder }
+
+package object newtype {
+  implicit def coercibleDecoder[A: Coercible[B, *], B: JsonDecoder]: JsonDecoder[A] =
+    JsonDecoder[B].map(_.coerce[A])
+
+  implicit def coercibleEncoder[A: Coercible[*, B], B: JsonEncoder]: JsonEncoder[A] =
+    JsonEncoder[B].contramap(_.coerce[B])
+
+  implicit def coercibleKeyDecoder[A: Coercible[B, *], B: JsonFieldDecoder]: JsonFieldDecoder[A] =
+    JsonFieldDecoder[B].map(_.coerce[A])
+
+  implicit def coercibleKeyEncoder[A: Coercible[*, B], B: JsonFieldEncoder]: JsonFieldEncoder[A] =
+    JsonFieldEncoder[B].contramap(_.coerce[B])
+}

zio-json-interop-newtype/shared/src/test/scala/zio/json/interop/newtype/NewtypeSpec.scala

@@ -0,0 +1,22 @@
+package zio.json.interop.newtype
+
+import io.estatico.newtype.macros.newtype
+import zio.json.{ DecoderOps, DeriveJsonDecoder, DeriveJsonEncoder, JsonDecoder, JsonEncoder }
+import zio.test.Assertion.{ equalTo, isRight }
+import zio.test.{ Spec, ZIOSpecDefault, assert, assertTrue }
+
+object NewtypeSpec extends ZIOSpecDefault {
+  override def spec: Spec[Environment, Any] = suite("newtype")(
+    test("newtype") {
+      assert("""{"name":"fommil"}""".fromJson[Person])(isRight(equalTo(Person(Name("fommil"))))) &&
+      assertTrue(Person(Name("fommil")).toJson == """{"name":"fommil"}""")
+    }
+  )
+
+  @newtype case class Name(value: String)
+  case class Person(name: Name)
+  object Person {
+    implicit val encoder: JsonEncoder[Person] = DeriveJsonEncoder.gen[Person]
+    implicit val decoder: JsonDecoder[Person] = DeriveJsonDecoder.gen[Person]
+  }
+}