From ee114a6a1c9fc86f34d9d42473bc75c1ca460db2 Mon Sep 17 00:00:00 2001
From: amsavchuk <savchukalexander@gmail.com>
Date: Mon, 13 May 2024 22:10:05 +0400
Subject: [PATCH] encodeJsonArrayPipeline produces incorrect JSON when stream
 is empty

---
 .../zio/json/JsonEncoderPlatformSpecific.scala  | 17 ++++++++++-------
 .../zio/json/EncoderPlatformSpecificSpec.scala  | 10 +++++++++-
 .../src/test/scala/zio/json/ast/JsonSpec.scala  | 10 ++++++++++
 3 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/zio-json/jvm/src/main/scala/zio/json/JsonEncoderPlatformSpecific.scala b/zio-json/jvm/src/main/scala/zio/json/JsonEncoderPlatformSpecific.scala
index 516fc41fd..3502c7270 100644
--- a/zio-json/jvm/src/main/scala/zio/json/JsonEncoderPlatformSpecific.scala
+++ b/zio-json/jvm/src/main/scala/zio/json/JsonEncoderPlatformSpecific.scala
@@ -43,17 +43,20 @@ trait JsonEncoderPlatformSpecific[A] { self: JsonEncoder[A] =>
                         )
                       }
                     }
-          writeWriter <- ZIO.succeed(new WriteWriter(writer))
+          writeWriter          <- ZIO.succeed(new WriteWriter(writer))
+          hasAtLeastOneElement <- Ref.make(false)
           push = { (is: Option[Chunk[A]]) =>
             val pushChars = chunkBuffer.getAndUpdate(c => if (c.isEmpty) c else Chunk())
 
             is match {
               case None =>
-                ZIO.attemptBlocking(writer.close()) *> pushChars.map { terminal =>
-                  endWith.fold(terminal) { last =>
-                    // Chop off terminal delimiter
-                    (if (delimiter.isDefined) terminal.dropRight(1) else terminal) :+ last
-                  }
+                ZIO.attemptBlocking(writer.close()) *> pushChars.flatMap { terminal =>
+                  hasAtLeastOneElement.get.map(nonEmptyStream =>
+                    endWith.fold(terminal) { last =>
+                      // Chop off terminal delimiter if stream is not empty
+                      (if (delimiter.isDefined && nonEmptyStream) terminal.dropRight(1) else terminal) :+ last
+                    }
+                  )
                 }
 
               case Some(xs) =>
@@ -64,7 +67,7 @@ trait JsonEncoderPlatformSpecific[A] { self: JsonEncoder[A] =>
                     for (s <- delimiter)
                       writeWriter.write(s)
                   }
-                } *> pushChars
+                } *> hasAtLeastOneElement.set(true).when(xs.nonEmpty) *> pushChars
             }
           }
         } yield push
diff --git a/zio-json/jvm/src/test/scala-2/zio/json/EncoderPlatformSpecificSpec.scala b/zio-json/jvm/src/test/scala-2/zio/json/EncoderPlatformSpecificSpec.scala
index ba37179d5..7479e378b 100644
--- a/zio-json/jvm/src/test/scala-2/zio/json/EncoderPlatformSpecificSpec.scala
+++ b/zio-json/jvm/src/test/scala-2/zio/json/EncoderPlatformSpecificSpec.scala
@@ -7,7 +7,7 @@ import testzio.json.data.googlemaps._
 import testzio.json.data.twitter._
 import zio.Chunk
 import zio.json.ast.Json
-import zio.stream.ZStream
+import zio.stream.{ ZSink, ZStream }
 import zio.test.Assertion._
 import zio.test.{ ZIOSpecDefault, assert, _ }
 
@@ -75,6 +75,14 @@ object EncoderPlatformSpecificSpec extends ZIOSpecDefault {
           } yield {
             assert(xs.mkString)(equalTo("""[{"id":1},{"id":2},{"id":3}]"""))
           }
+        },
+        test("encodeJsonArrayPipeline, empty stream") {
+          val emptyArray = ZStream
+            .from(List())
+            .via(JsonEncoder[String].encodeJsonArrayPipeline)
+            .run(ZSink.mkString)
+
+          assertZIO(emptyArray)(equalTo("[]"))
         }
       ),
       suite("helpers in zio.json")(
diff --git a/zio-json/shared/src/test/scala/zio/json/ast/JsonSpec.scala b/zio-json/shared/src/test/scala/zio/json/ast/JsonSpec.scala
index 996a5b847..069f16594 100644
--- a/zio-json/shared/src/test/scala/zio/json/ast/JsonSpec.scala
+++ b/zio-json/shared/src/test/scala/zio/json/ast/JsonSpec.scala
@@ -267,6 +267,16 @@ object JsonSpec extends ZIOSpecDefault {
           assert(posts.get(combined))(
             isRight(equalTo(Json.Str("foo")))
           )
+        },
+        test(">>>, identity") {
+          val obj = Json.Obj("a" -> Json.Num(1))
+
+          val fieldA   = JsonCursor.field("a")
+          val identity = JsonCursor.identity
+
+          val num = obj.get(fieldA >>> identity)
+
+          assert(num)(isRight(equalTo(Json.Num(1))))
         }
       ),
       suite("intersect")(