Fix for _schema_version overriding non-object entity data

We recommend that Snowplow entities should be JSON *objects* only. But
technically it is possible for them to be something else, e.g. a JSON
array.

Since version 3.2.0 we started adding the `_schema_version` field to
context entities, see #132. But this accidentally clobbered the original
data if the entity was not an object. This commit fixes the problem by
only adding `_schema_version` if the entity is an object.

build.sbt

@@ -46,7 +46,8 @@ lazy val root = project
       // Scala (test only)
       Dependencies.specs2,
       Dependencies.specs2Scalacheck,
-      Dependencies.scalacheck
+      Dependencies.scalacheck,
+      Dependencies.circeLiteral
     )
   )
 

project/Dependencies.scala

@@ -31,4 +31,5 @@ object Dependencies {
   val specs2           = "org.specs2"                 %% "specs2-core"          % V.specs2     % Test
   val specs2Scalacheck = "org.specs2"                 %% "specs2-scalacheck"    % V.specs2     % Test
   val scalacheck       = "org.scalacheck"             %% "scalacheck"           % V.scalaCheck % Test
+  val circeLiteral     = "io.circe"                   %% "circe-literal"        % V.circe      % Test
 }

src/main/scala/com.snowplowanalytics.snowplow.analytics.scalasdk/SnowplowEvent.scala

@@ -68,10 +68,11 @@ object SnowplowEvent {
       }
   }
 
-  private def addSchemaVersionToData(contextSdd: SelfDescribingData[Json]): Json = {
-    val version = Json.obj("_schema_version" -> contextSdd.schema.version.asString.asJson)
-    contextSdd.data.deepMerge(version)
-  }
+  private def addSchemaVersionToData(contextSdd: SelfDescribingData[Json]): Json =
+    if (contextSdd.data.isObject) {
+      val version = Json.obj("_schema_version" -> contextSdd.schema.version.asString.asJson)
+      contextSdd.data.deepMerge(version)
+    } else contextSdd.data
 
   implicit final val contextsCirceEncoder: Encoder[Contexts] =
     Encoder.instance { contexts =>

src/test/scala/com.snowplowanalytics.snowplow.analytics.scalasdk/SnowplowEventSpec.scala

@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2016-2020 Snowplow Analytics Ltd. All rights reserved.
+ *
+ * This program is licensed to you under the Apache License Version 2.0,
+ * and you may not use this file except in compliance with the Apache License Version 2.0.
+ * You may obtain a copy of the Apache License Version 2.0 at http://www.apache.org/licenses/LICENSE-2.0.
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the Apache License Version 2.0 is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the Apache License Version 2.0 for the specific language governing permissions and limitations there under.
+ */
+
+package com.snowplowanalytics.snowplow.analytics.scalasdk
+
+// java
+import java.time.Instant
+import java.util.UUID
+import java.nio.ByteBuffer
+import java.nio.charset.StandardCharsets
+
+// cats
+import cats.data.Validated.{Invalid, Valid}
+import cats.data.NonEmptyList
+import cats.syntax.either._
+
+// circe
+import io.circe.{Decoder, Encoder, Json, JsonObject}
+import io.circe.syntax._
+import io.circe.parser._
+import io.circe.generic.semiauto._
+import io.circe.literal._
+
+// Specs2
+import org.specs2.mutable.Specification
+
+// Iglu
+import com.snowplowanalytics.iglu.core.{SchemaKey, SelfDescribingData}
+
+/**
+ * Tests Event case class
+ */
+class SnowplowEventSpec extends Specification {
+  import EventSpec._
+
+  "Contexts toShreddedJson" should {
+    "return a map of JSON entities, keyed by column name" in {
+
+      val sdd1 = SelfDescribingData[Json](SchemaKey.fromUri("iglu:myvendor1/myname1/jsonschema/1-2-3").toOption.get, json"""{"xyz": 42}""")
+      val sdd2 =
+        SelfDescribingData[Json](SchemaKey.fromUri("iglu:myvendor2/myname2/jsonschema/2-3-4").toOption.get, json"""{"abc": true}""")
+
+      val input = SnowplowEvent.Contexts(List(sdd1, sdd2))
+
+      val result = input.toShreddedJson
+
+      val expected = Map(
+        "contexts_myvendor1_myname1_1" -> json"""[{"_schema_version": "1-2-3", "xyz": 42}]""",
+        "contexts_myvendor2_myname2_2" -> json"""[{"_schema_version": "2-3-4", "abc": true}]"""
+      )
+
+      result must beEqualTo(expected)
+
+    }
+
+    "return a map of JSON entities for all types of JSON value (object, array, string, number, boolean, null)" in {
+
+      def sdd(version: Int, v: Json): SelfDescribingData[Json] =
+        SelfDescribingData[Json](SchemaKey.fromUri(s"iglu:myvendor/myname/jsonschema/$version-0-0").toOption.get, v)
+
+      val input = SnowplowEvent.Contexts(
+        List(
+          sdd(1, json"""{"xyz": 123}"""),
+          sdd(2, json"""[1, 2, 3]"""),
+          sdd(3, json""""foo""""),
+          sdd(4, json"""42"""),
+          sdd(5, json"""true"""),
+          sdd(6, json"""null""")
+        )
+      )
+
+      val result = input.toShreddedJson
+
+      val expected = Map(
+        "contexts_myvendor_myname_1" -> json"""[{"_schema_version": "1-0-0", "xyz": 123}]""",
+        "contexts_myvendor_myname_2" -> json"""[[1, 2, 3]]""",
+        "contexts_myvendor_myname_3" -> json"""["foo"]""",
+        "contexts_myvendor_myname_4" -> json"""[42]""",
+        "contexts_myvendor_myname_5" -> json"""[true]""",
+        "contexts_myvendor_myname_6" -> json"""[null]"""
+      )
+
+      result must beEqualTo(expected)
+
+    }
+  }
+}