Add a key serializer unit test from #838

src/test/java/com/fasterxml/jackson/databind/ser/TestKeySerializers.java

@@ -3,10 +3,12 @@
 import java.io.IOException;
 import java.util.*;
 
+import com.fasterxml.jackson.annotation.*;
 import com.fasterxml.jackson.core.JsonGenerator;
-
+import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.*;
 import com.fasterxml.jackson.databind.annotation.JsonSerialize;
+import com.fasterxml.jackson.databind.jsontype.TypeResolverBuilder;
 import com.fasterxml.jackson.databind.module.SimpleModule;
 
 public class TestKeySerializers extends BaseMapTest
@@ -40,7 +42,7 @@ enum ABC {
         A, B, C
     }
 
-    static class ABCSerializer extends JsonSerializer<ABC> {
+    static class ABCKeySerializer extends JsonSerializer<ABC> {
         @Override
         public void serialize(ABC value, JsonGenerator jgen,
                 SerializerProvider provider) throws IOException {
@@ -55,6 +57,26 @@ public ABCMapWrapper() {
         }
     }
 
+    static class BAR<T>{
+        T value;
+
+        public BAR(T value) {
+            this.value = value;
+        }
+
+        @JsonValue
+        public T getValue() {
+            return value;
+        }
+
+        @Override
+        public String toString() {
+            return this.getClass().getSimpleName()
+                    + ", value:" + value
+                    ;
+        }
+    }
+
     /*
     /**********************************************************
     /* Unit tests
@@ -88,10 +110,50 @@ public void testCustomForEnum() throws IOException
     {
         final ObjectMapper mapper = new ObjectMapper();
         SimpleModule mod = new SimpleModule("test");
-        mod.addKeySerializer(ABC.class, new ABCSerializer());
+        mod.addKeySerializer(ABC.class, new ABCKeySerializer());
         mapper.registerModule(mod);
 
         String json = mapper.writeValueAsString(new ABCMapWrapper());
         assertEquals("{\"stuff\":{\"xxxB\":\"bar\"}}", json);
     }
+
+    // [databind#838]
+    public void testUnWrappedMapWithDefaultType() throws Exception{
+        final ObjectMapper mapper = new ObjectMapper();
+        SimpleModule mod = new SimpleModule("test");
+        mod.addKeySerializer(ABC.class, new ABCKeySerializer());
+        mapper.registerModule(mod);
+
+        TypeResolverBuilder<?> typer = new ObjectMapper.DefaultTypeResolverBuilder(ObjectMapper.DefaultTyping.NON_FINAL);
+        typer = typer.init(JsonTypeInfo.Id.NAME, null);
+        typer = typer.inclusion(JsonTypeInfo.As.PROPERTY);
+        //typer = typer.typeProperty(TYPE_FIELD);
+        typer = typer.typeIdVisibility(true);
+        mapper.setDefaultTyping(typer);
+
+        Map<ABC,String> stuff = new HashMap<ABC,String>();
+        stuff.put(ABC.B, "bar");
+        String json = mapper.writerFor(new TypeReference<Map<ABC, String>>() {})
+                .writeValueAsString(stuff);
+        assertEquals("{\"@type\":\"HashMap\",\"xxxB\":\"bar\"}", json);
+    }
+
+    // [databind#838]
+    public void testUnWrappedMapWithKeySerializer() throws Exception{
+        SimpleModule mod = new SimpleModule("test");
+        mod.addKeySerializer(ABC.class, new ABCKeySerializer());
+        final ObjectMapper mapper = new ObjectMapper()
+            .registerModule(mod)
+            .enable(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT)
+            .disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
+            .disable(SerializationFeature.WRITE_NULL_MAP_VALUES)
+            .setSerializationInclusion(JsonInclude.Include.NON_EMPTY)
+            ;
+
+        Map<ABC,BAR<?>> stuff = new HashMap<ABC,BAR<?>>();
+        stuff.put(ABC.B, new BAR<String>("bar"));
+        String json = mapper.writerFor(new TypeReference<Map<ABC,BAR<?>>>() {})
+                .writeValueAsString(stuff);
+        assertEquals("{\"xxxB\":\"bar\"}", json);
+    }
 }