add test that shows an issue when scala 2.13 or scala 3 used (#597)

Author: pjfanning

src/test/scala/com/fasterxml/jackson/module/scala/ser/CaseObjectSerializerTest.scala

@@ -1,5 +1,6 @@
 package com.fasterxml.jackson.module.scala.ser
 
+import com.fasterxml.jackson.annotation.{JsonAutoDetect, PropertyAccessor}
 import com.fasterxml.jackson.module.scala.DefaultScalaModule
 
 case object CaseObjectExample {
@@ -9,12 +10,35 @@ case object CaseObjectExample {
 
 class CaseObjectSerializerTest extends SerializerTest {
 
+  case object Foo {
+    val field: String = "bar"
+  }
+
   def module = DefaultScalaModule
 
   "An ObjectMapper with the DefaultScalaModule" should "serialize a case object as a bean" in {
     serialize(CaseObjectExample) should (
        equal ("""{"field1":"test","field2":42}""") or
-       equal ("""{"field2":42,"field1":"test"}""")
+         equal ("""{"field2":42,"field1":"test"}""")
     )
   }
+
+  it should "serialize a case object when visibility settings set" ignore {
+    val mapper = newBuilder
+      .visibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.ANY)
+      .visibility(PropertyAccessor.GETTER, JsonAutoDetect.Visibility.NONE)
+      .build()
+    mapper.writeValueAsString(CaseObjectExample) should (
+      equal("""{"field1":"test","field2":42}""") or
+        equal("""{"field2":42,"field1":"test"}""")
+    )
+  }
+
+  it should "serialize an inner case object when visibility settings set" in {
+    val mapper = newBuilder
+      .visibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.ANY)
+      .visibility(PropertyAccessor.GETTER, JsonAutoDetect.Visibility.NONE)
+      .build()
+    mapper.writeValueAsString(Foo) shouldEqual """{"field":"bar"}"""
+  }
 }