Add testing of default values for cases of nested options

Author: plokhotnyuk

jsoniter-scala-macros/shared/src/test/scala/com/github/plokhotnyuk/jsoniter_scala/macros/JsonCodecMakerSpec.scala

@@ -1173,7 +1173,7 @@ class JsonCodecMakerSpec extends VerifyingSpec {
         """{"param1":"A","param2":"B","payload":{"x":[-1.0,1,4.0E20],"y":{"xx":true,"yy":false,"zz":null},"z":"Z"},"param3":"C"}""")
     }
     "serialize and deserialize nested options without loss of information" in {
-      case class NestedOptions(x: Option[Option[Option[String]]])
+      case class NestedOptions(x: Option[Option[Option[String]]] = _root_.scala.None)
 
       val codecOfNestedOptions = make[NestedOptions]
       verifySerDeser(codecOfNestedOptions, NestedOptions(_root_.scala.None), """{}""")
@@ -1186,15 +1186,20 @@ class JsonCodecMakerSpec extends VerifyingSpec {
         """{"x":{"type":"Some","value":{"type":"None"}}}""")
     }
     "serialize and deserialize Option[Option[_]] to distinguish `null` field values and missing fields" in {
-      case class Model(field1: String, field2: Option[Option[String]])
+      case class Model(field1: Option[Option[String]], field2: Option[Option[String]] = _root_.scala.None)
 
       verifySerDeser(make[List[Model]](CodecMakerConfig.withSkipNestedOptionValues(true)),
-        List(Model("VVV", _root_.scala.Some(_root_.scala.Some("WWW"))), Model("VVV", _root_.scala.None), Model("VVV", _root_.scala.Some(_root_.scala.None))),
-        """[{"field1":"VVV","field2":"WWW"},{"field1":"VVV"},{"field1":"VVV","field2":null}]""")
-
+        List(
+          Model(_root_.scala.Some(_root_.scala.Some("VVV")), _root_.scala.Some(_root_.scala.Some("WWW"))),
+          Model(_root_.scala.None),
+          Model(_root_.scala.Some(_root_.scala.None), _root_.scala.Some(_root_.scala.None))),
+        """[{"field1":"VVV","field2":"WWW"},{},{"field1":null,"field2":null}]""")
       verifySerDeser(makeWithSkipNestedOptionValues[List[Model]],
-        List(Model("VVV", _root_.scala.Some(_root_.scala.Some("WWW"))), Model("VVV", _root_.scala.None), Model("VVV", _root_.scala.Some(_root_.scala.None))),
-        """[{"field1":"VVV","field2":"WWW"},{"field1":"VVV"},{"field1":"VVV","field2":null}]""")
+        List(
+          Model(_root_.scala.Some(_root_.scala.Some("VVV")), _root_.scala.Some(_root_.scala.Some("WWW"))),
+          Model(_root_.scala.None),
+          Model(_root_.scala.Some(_root_.scala.None), _root_.scala.Some(_root_.scala.None))),
+        """[{"field1":"VVV","field2":"WWW"},{},{"field1":null,"field2":null}]""")
     }
     "serialize and deserialize Nullable[_] to distinguish `null` field values and missing fields using a custom value codec" in {
       sealed trait Nullable[+A]