FIX/345 : Serializing enums as property or as Map key has different b…

…ehavior in case of toString overriding

Signed-off-by: Sébastien RIUS <sebastien.rius@capgemini.com>

src/main/java/org/eclipse/yasson/internal/serializer/MapToObjectSerializer.java

@@ -12,10 +12,9 @@
  ******************************************************************************/
 package org.eclipse.yasson.internal.serializer;
 
-import java.util.Map;
-
 import javax.json.bind.serializer.SerializationContext;
 import javax.json.stream.JsonGenerator;
+import java.util.Map;
 
 /**
  * Serialize {@link Map} with {@link String} keys as JSON Object:
@@ -77,8 +76,14 @@ public void writeStart(String key, JsonGenerator generator) {
      */
     @Override
     public void serializeContainer(Map<K,V> obj, JsonGenerator generator, SerializationContext ctx) {
-        for (Map.Entry<?,?> entry : obj.entrySet()) {
-            final String keyString = String.valueOf(entry.getKey());
+        for (Map.Entry<K,V> entry : obj.entrySet()) {
+            final String keyString;
+            K key = entry.getKey();
+            if (key instanceof Enum<?>) {
+                keyString = ((Enum<?>) key).name();
+            } else {
+                keyString = String.valueOf(key);
+            }
             final Object value = entry.getValue();
             if (value == null) {
                 if (serializer.isNullable()) {

src/test/java/org/eclipse/yasson/serializers/MapToObjectSerializerTest.java

@@ -0,0 +1,59 @@
+/*******************************************************************************
+ * Copyright (c) 2019 Oracle and/or its affiliates. All rights reserved.
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
+ * which accompanies this distribution.
+ * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
+ * and the Eclipse Distribution License is available at
+ * http://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * Contributors:
+ * Sebastien Rius
+ ******************************************************************************/
+package org.eclipse.yasson.serializers;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import javax.json.bind.Jsonb;
+import javax.json.bind.JsonbBuilder;
+import javax.json.bind.JsonbConfig;
+import java.util.EnumMap;
+import java.util.Map;
+
+/**
+ * Test various use-cases with {@code Map} serializer which
+ * stores Map as JSON object.
+ */
+public class MapToObjectSerializerTest {
+
+    /**
+     * Enum used as key in maps during tests
+     */
+    enum TestEnum {
+        ONE, TWO;
+
+        @Override
+        /**
+         * Force to lower case to check toString is not used during serialization of maps
+         */
+        public String toString() {
+            return this.name().toLowerCase();
+        }
+    }
+
+    /**
+     * Test serialization of Map with Number keys and String values.
+     */
+    @Test
+    public void testSerializeEnumMapToObject() {
+        Map<TestEnum, Object> map = new EnumMap<>(TestEnum.class);
+        Jsonb jsonb = JsonbBuilder.create(new JsonbConfig().withFormatting(true));
+        map.put(TestEnum.ONE, "value1");
+        map.put(TestEnum.TWO, "value2");
+        String json = jsonb.toJson(map);
+        for (TestEnum e : TestEnum.values()) {
+            Assert.assertTrue("Enumeration not well serialized", json.contains(e.name()));
+        }
+    }
+}