From 8506c369818228b77458efe248767c311e37ffee Mon Sep 17 00:00:00 2001
From: Simon Schenk <simon.schenk@ziverge.com>
Date: Mon, 22 Apr 2024 09:43:55 +0200
Subject: [PATCH] fix: decode ADT with 3 cases with noDiscriminator

---
 .../scala/zio/schema/codec/JsonCodec.scala    |  3 ++-
 .../zio/schema/codec/JsonCodecSpec.scala      | 26 +++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/zio-schema-json/shared/src/main/scala/zio/schema/codec/JsonCodec.scala b/zio-schema-json/shared/src/main/scala/zio/schema/codec/JsonCodec.scala
index 582eff73e..758b5adbd 100644
--- a/zio-schema-json/shared/src/main/scala/zio/schema/codec/JsonCodec.scala
+++ b/zio-schema-json/shared/src/main/scala/zio/schema/codec/JsonCodec.scala
@@ -711,7 +711,7 @@ object JsonCodec {
 
         (trace: List[JsonError], in: RetractReader) => {
           if (noDiscriminators) {
-            val rr                = RecordingReader(in)
+            var rr                = RecordingReader(in)
             val it                = cases.iterator
             var result: Option[Z] = None
 
@@ -723,6 +723,7 @@ object JsonCodec {
               } catch {
                 case _: Exception =>
                   rr.rewind()
+                  if (result.isEmpty && it.hasNext) rr = RecordingReader(rr)
               }
             }
 
diff --git a/zio-schema-json/shared/src/test/scala-2/zio/schema/codec/JsonCodecSpec.scala b/zio-schema-json/shared/src/test/scala-2/zio/schema/codec/JsonCodecSpec.scala
index 243ef029e..923c19da5 100644
--- a/zio-schema-json/shared/src/test/scala-2/zio/schema/codec/JsonCodecSpec.scala
+++ b/zio-schema-json/shared/src/test/scala-2/zio/schema/codec/JsonCodecSpec.scala
@@ -1184,6 +1184,18 @@ object JsonCodecSpec extends ZIOSpecDefault {
           Enumeration2(BooleanValue2(false))
         )
       },
+      test("ADT with noDiscriminator") {
+        assertEncodesThenDecodes(
+          Schema[Enumeration3],
+          Enumeration3(StringValue3("foo"))
+        ) &> assertEncodesThenDecodes(
+          Schema[Enumeration3],
+          Enumeration3(StringValue3Multi("foo", "bar"))
+        ) &> assertEncodesThenDecodes(Schema[Enumeration3], Enumeration3(IntValue3(-1))) &> assertEncodesThenDecodes(
+          Schema[Enumeration3],
+          Enumeration3(BooleanValue3(false))
+        ) &> assertEncodesThenDecodes(Schema[Enumeration3], Enumeration3(Nested(StringValue3("foo"))))
+      },
       test("of case classes with discriminator") {
         assertEncodesThenDecodes(Schema[Command], Command.Cash) &>
           assertEncodesThenDecodes(Schema[Command], Command.Buy(100))
@@ -1673,6 +1685,20 @@ object JsonCodecSpec extends ZIOSpecDefault {
     implicit val schema: Schema[Enumeration2] = DeriveSchema.gen[Enumeration2]
   }
 
+  @noDiscriminator
+  sealed trait OneOf3
+  case class StringValue3(value: String)                       extends OneOf3
+  case class IntValue3(value: Int)                             extends OneOf3
+  case class BooleanValue3(value: Boolean)                     extends OneOf3
+  case class StringValue3Multi(value1: String, value2: String) extends OneOf3
+  case class Nested(oneOf: OneOf3)                             extends OneOf3
+
+  case class Enumeration3(oneOf: OneOf3)
+
+  object Enumeration3 {
+    implicit val schema: Schema[Enumeration3] = DeriveSchema.gen[Enumeration3]
+  }
+
   sealed trait Color
 
   object Color {