Add unit tests and fix behavior with default parameters

3 files changed, 29 insertions, 10 deletions

diff --git a/.gitignore b/.gitignore
index e7f1455..ffa0d68 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@ target
 .jvm
 .js
 .native
+.idea/
diff --git a/core/shared/src/main/scala/magnolia.scala b/core/shared/src/main/scala/magnolia.scala
index 49b2744..2431e4f 100644
--- a/core/shared/src/main/scala/magnolia.scala
+++ b/core/shared/src/main/scala/magnolia.scala
@@ -278,16 +278,26 @@ object Magnolia {
         val preAssignments = caseParams.map(_.typeclass)
 
         val defaults = if (!isValueClass) {
-          val indexedConstructorParams = genericType.decls.collect {
-            case m: MethodSymbol if m.isCaseAccessor => m.asTerm
-          }.zipWithIndex
-
-          indexedConstructorParams.map {
-            case (p, idx) =>
-              if (p.isParamWithDefault) {
-                val method = TermName("apply$default$" + (idx + 1))
-                q"$scalaPkg.Some(${genericType.typeSymbol.companion.asTerm}.$method)"
-              } else q"$scalaPkg.None"
+          val constructorParams = genericType.decls.collect {
+            case a: MethodSymbol if a.isConstructor => a
+          }.head.paramLists.head.map(_.asTerm)
+          val noDefaults = constructorParams.forall(!_.isParamWithDefault)
+
+          if (noDefaults) {
+            constructorParams.map(_ => q"$scalaPkg.None")
+          } else {
+            val caseClassCompanion = genericType.companion
+            val constructorMethod = caseClassCompanion.decl(TermName("apply")).asMethod
+            val indexedConstructorParams =
+              constructorMethod.paramLists.head.map(_.asTerm).zipWithIndex
+
+            indexedConstructorParams.map {
+              case (p, idx) =>
+                if (p.isParamWithDefault) {
+                  val method = TermName("apply$default$" + (idx + 1))
+                  q"$scalaPkg.Some(${genericType.typeSymbol.companion.asTerm}.$method)"
+                } else q"$scalaPkg.None"
+            }
           }
         } else List(q"$scalaPkg.None")
 
diff --git a/tests/src/main/scala/tests.scala b/tests/src/main/scala/tests.scala
index e453502..6810fc9 100644
--- a/tests/src/main/scala/tests.scala
+++ b/tests/src/main/scala/tests.scala
@@ -176,5 +176,13 @@ object Tests extends TestApp {
     test("serialize a value class") {
       Show.gen[Length].show(new Length(100))
     }.assert(_ == "100")
+
+    class ParentClass {
+      case class InnerClass(name: String)
+
+      test("serialize a case class inside another class") {
+        implicitly[Show[String, InnerClass]].show(InnerClass("foo"))
+      }.assert(_ == "InnerClass(name=foo)")
+    }
   }
 }