3 files changed, 132 insertions, 0 deletions
diff --git a/src/test/scala/CoproductTypeFormats.scala b/src/test/scala/CoproductTypeFormats.scala
new file mode 100644
index 0000000..f16e4c7
--- /dev/null
+++ b/src/test/scala/CoproductTypeFormats.scala
@@ -0,0 +1,58 @@
+package xyz.driver.json
+
+import spray.json._
+
+import org.scalatest._
+
+class CoproductTypeFormats
+    extends FlatSpec
+    with FormatTests
+    with DefaultJsonProtocol
+    with DerivedFormats {
+
+  sealed trait Expr
+  case class Zero() extends Expr
+  case class Value(x: Int) extends Expr
+  case class Plus(lhs: Expr, rhs: Expr) extends Expr
+  case object One extends Expr
+
+  "No-parameter case class child" should behave like checkCoherence[Expr](
+    Zero(),
+    """{"type":"Zero"}"""
+  )
+
+  "Simple parameter case class child" should behave like checkCoherence[Expr](
+    Value(42),
+    """{"type":"Value","x":42}"""
+  )
+
+  "Nested parameter case class child" should behave like checkCoherence[Expr](
+    Plus(Value(42), Value(0)),
+    """{"type":"Plus","lhs":{"type":"Value","x":42},"rhs":{"type":"Value","x":0}}"""
+  )
+
+  // "Case object child" should behave like checkCoherence[Expr](
+  //   One,
+  //   """{"type":"One"}"""
+  // )
+
+  @gadt("kind")
+  sealed abstract class Keyword(`type`: String)
+  case class If(`type`: String) extends Keyword(`type`)
+
+  "GADT with type field alias" should behave like checkCoherence[Keyword](
+    If("class"),
+    """{"kind":"If","type":"class"}"""
+  )
+
+  @enum
+  sealed trait Enum
+  case object A extends Enum
+  case object B extends Enum
+
+  "Enum" should behave like checkCoherence[List[Enum]](
+    A :: B :: Nil,
+    """["A", "B"]"""
+  )
+
+}
diff --git a/src/test/scala/FormatTests.scala b/src/test/scala/FormatTests.scala
new file mode 100644
index 0000000..e29e49f
--- /dev/null
+++ b/src/test/scala/FormatTests.scala
@@ -0,0 +1,20 @@
+package xyz.driver.json
+
+import spray.json._
+import org.scalatest._
+
+trait FormatTests { self: FlatSpec =>
+
+  def checkCoherence[A: JsonFormat](a: A, expectedJson: String) = {
+    it should "serialize to the expected JSON value" in {
+      val expected: JsValue = expectedJson.parseJson
+      assert(a.toJson == expected)
+    }
+
+    it should "serialize then deserialize back to itself" in {
+      val reread = a.toJson.convertTo[A]
+      assert(reread == a)
+    }
+  }
+
+}
diff --git a/src/test/scala/ProductTypeFormats.scala b/src/test/scala/ProductTypeFormats.scala
new file mode 100644
index 0000000..9755198
--- /dev/null
+++ b/src/test/scala/ProductTypeFormats.scala
@@ -0,0 +1,54 @@
+package xyz.driver.json
+
+import spray.json._
+
+import org.scalatest._
+
+class ProductTypeFormats
+    extends FlatSpec
+    with FormatTests
+    with DerivedFormats
+    with DefaultJsonProtocol {
+
+  case class A()
+  case class B(x: Int, b: String, mp: Map[String, Int])
+  case class C(b: B)
+  case object D
+  case class E(d: D.type)
+  case class F(x: Int)
+
+  "No-parameter product" should behave like checkCoherence(A(), "{}")
+
+  "Simple parameter product" should behave like checkCoherence(
+    B(42, "Hello World", Map("a" -> 1, "b" -> -1024)),
+    """{ "x": 42, "b": "Hello World", "mp": { "a": 1, "b": -1024 } }"""
+  )
+
+  "Nested parameter product" should behave like checkCoherence(
+    C(B(42, "Hello World", Map("a" -> 1, "b" -> -1024))),
+    """{"b" :{ "x": 42, "b": "Hello World", "mp": { "a": 1, "b": -1024 } } }"""
+  )
+
+  "Case object" should behave like checkCoherence(
+    D,
+    """"D""""
+  )
+
+  "Case object as parameter" should behave like checkCoherence(
+    E(D),
+    """{"d":"D"}"""
+  )
+
+  // custom format for F, that inverts the value of parameter x
+  implicit val fFormat: JsonFormat[F] = new JsonFormat[F] {
+    override def write(f: F): JsValue = JsObject("x" -> JsNumber(-f.x))
+    override def read(js: JsValue): F =
+      F(-js.asJsObject.fields("x").convertTo[Int])
+  }
+
+  "Overriding with a custom format" should behave like checkCoherence(
+    F(2),
+    """{"x":-2}"""
+  )
+
+}