Add jackson behavior for methods

Added classes to make gson treat methods as jackson does.
Remove unneeded "forGetter" parameter from constructors.
Fixed sonar issue with too long "if" test.
Corrected comment about annotation names.
Adjusted error message.
Removed unused constant.
Removed trailing spaces.

Change-Id: I3a4fc92193737a0dc89f1218e70f093aedbdb152
Issue-ID: POLICY-1428
Signed-off-by: Jim Hahn <jrh3@att.com>

8 files changed, 844 insertions, 4 deletions

diff --git a/gson/src/test/java/org/onap/policy/common/gson/JacksonMethodAdapterFactoryTest.java b/gson/src/test/java/org/onap/policy/common/gson/JacksonMethodAdapterFactoryTest.java
new file mode 100644
index 00000000..47cf4b3b
--- /dev/null
+++ b/gson/src/test/java/org/onap/policy/common/gson/JacksonMethodAdapterFactoryTest.java
@@ -0,0 +1,311 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.gson;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonElement;
+import com.google.gson.reflect.TypeToken;
+import java.util.Map;
+import java.util.TreeMap;
+import org.junit.Test;
+import org.onap.policy.common.gson.JacksonExclusionStrategy;
+import org.onap.policy.common.gson.JacksonMethodAdapterFactory;
+import org.onap.policy.common.gson.annotation.GsonJsonAnyGetter;
+import org.onap.policy.common.gson.annotation.GsonJsonAnySetter;
+import org.onap.policy.common.gson.annotation.GsonJsonIgnore;
+import org.onap.policy.common.gson.annotation.GsonJsonProperty;
+
+public class JacksonMethodAdapterFactoryTest {
+
+    private static JacksonMethodAdapterFactory factory = new JacksonMethodAdapterFactory();
+
+    private static Gson gson = new GsonBuilder().setExclusionStrategies(new JacksonExclusionStrategy())
+                    .registerTypeAdapterFactory(factory).create();
+
+    @Test
+    public void testCreate() {
+        // unhandled types
+        assertNull(factory.create(gson, TypeToken.get(JsonElement.class)));
+        assertNull(factory.create(gson, TypeToken.get(NothingToSerialize.class)));
+
+        assertNotNull(factory.create(gson, TypeToken.get(Data.class)));
+        assertNotNull(factory.create(gson, TypeToken.get(Derived.class)));
+        assertNotNull(factory.create(gson, TypeToken.get(OnlyGetters.class)));
+        assertNotNull(factory.create(gson, TypeToken.get(OnlySetters.class)));
+        assertNotNull(factory.create(gson, TypeToken.get(OnlyAnyGetter.class)));
+        assertNotNull(factory.create(gson, TypeToken.get(OnlyAnySetter.class)));
+
+        // unhandled type
+
+        Data data = new Data();
+        data.id = 10;
+        data.text = "some text";
+
+        String result = gson.toJson(data);
+        Data data2 = gson.fromJson(result, Data.class);
+        assertEquals(data.toString(), data2.toString());
+
+        Derived der = new Derived();
+        der.setId(20);
+        der.setText("hello");
+        der.text = "world";
+        der.map = new TreeMap<>();
+        der.map.put("mapA", "valA");
+        der.map.put("mapB", "valB");
+
+        result = gson.toJson(der);
+
+        // should not contain the unserialized fields
+        assertFalse(result.contains("hello"));
+        assertFalse(result.contains("world"));
+
+        // null out unserialized fields
+        der.text = null;
+
+        // null out overridden field
+        der.setText(null);
+
+        Derived der2 = gson.fromJson(result, Derived.class);
+
+        assertEquals(der.toString(), der2.toString());
+
+        // override of AnyGetter
+        AnyGetterOverride dblget = new AnyGetterOverride();
+        dblget.setMap(der.map);
+        dblget.overMap = new TreeMap<>();
+        dblget.overMap.put("getA", 100);
+        dblget.overMap.put("getB", 110);
+
+        String result2 = gson.toJson(dblget);
+        dblget.overMap.keySet().forEach(key -> assertTrue("over contains " + key, result2.contains(key)));
+        der.map.keySet().forEach(key -> assertFalse("sub contains " + key, result2.contains(key)));
+
+        // override of AnySetter
+        Map<String, Integer> map = new TreeMap<>();
+        map.put("setA", 200);
+        map.put("setB", 210);
+        AnySetterOverride dblset = gson.fromJson(gson.toJson(map), AnySetterOverride.class);
+        assertEquals(map.toString(), dblset.overMap.toString());
+        assertNull(dblset.getTheMap());
+
+        // non-static nested class - can serialize, but not de-serialize
+        Container cont = new Container(500, "bye bye");
+        result = gson.toJson(cont);
+        assertEquals("{'id':500,'nested':{'value':'bye bye'}}".replace('\'', '"'), result);
+    }
+
+    protected static class Data {
+        private int id;
+        private String text;
+
+        public int getId() {
+            return id;
+        }
+
+        public void setId(int id) {
+            this.id = id;
+        }
+
+        // not public, but property provided
+        @GsonJsonProperty("text")
+        protected String getText() {
+            return text;
+        }
+
+        public void setText(String text) {
+            this.text = text;
+        }
+
+        public void unused(String text) {
+            // do nothing
+        }
+
+        @Override
+        public String toString() {
+            return "Data [id=" + id + ", text=" + text + "]";
+        }
+    }
+
+    protected static class Derived extends Data {
+
+        // overrides private field from Data
+        public String text;
+
+        private Map<String, String> map;
+
+        @GsonJsonAnyGetter
+        public Map<String, String> getTheMap() {
+            return map;
+        }
+
+        @GsonJsonIgnore
+        public void setMap(Map<String, String> map) {
+            this.map = map;
+        }
+
+        @GsonJsonAnySetter
+        public void setMapValue(String key, String value) {
+            if (map == null) {
+                map = new TreeMap<>();
+            }
+
+            map.put(key, value);
+        }
+
+        @Override
+        public String toString() {
+            return "Derived [text=" + text + ", map=" + map + ", toString()=" + super.toString() + "]";
+        }
+    }
+
+    /**
+     * Has {@link GsonJsonAnyGetter} method that overrides the super class' method.
+     */
+    private static class AnyGetterOverride extends Derived {
+        private Map<String, Integer> overMap;
+
+        @GsonJsonAnyGetter
+        private Map<String, Integer> getOverride() {
+            return overMap;
+        }
+    }
+
+    /**
+     * Has {@link GsonJsonAnySetter} method that overrides the super class' method.
+     */
+    private static class AnySetterOverride extends Derived {
+        private Map<String, Integer> overMap;
+
+        @GsonJsonAnySetter
+        private void setOverride(String key, int value) {
+            if (overMap == null) {
+                overMap = new TreeMap<>();
+            }
+
+            overMap.put(key, value);
+        }
+    }
+
+    /**
+     * Has nothing to serialize.
+     */
+    protected static class NothingToSerialize {
+        // not serialized
+        protected String unserialized;
+    }
+
+    /**
+     * Only has getters.
+     */
+    protected static class OnlyGetters {
+        public int getId() {
+            return 1010;
+        }
+    }
+
+    /**
+     * Only has setters.
+     */
+    protected static class OnlySetters {
+        public void setId(int id) {
+            // do nothing
+        }
+    }
+
+    /**
+     * Only has {@link GsonJsonAnyGetter}.
+     */
+    private static class OnlyAnyGetter {
+        @GsonJsonAnyGetter
+        public Map<String, Integer> getOverride() {
+            return null;
+        }
+    }
+
+    /**
+     * Only has {@link GsonJsonAnySetter}.
+     */
+    private static class OnlyAnySetter {
+        @GsonJsonAnySetter
+        public void setOverride(String key, int value) {
+            // do nothing
+        }
+    }
+
+    /**
+     * Used to test serialization of non-static nested classes.
+     */
+    protected static class Container {
+        private int id;
+        private Nested nested;
+
+        public Container() {
+            super();
+        }
+
+        public Container(int id, String value) {
+            this.id = id;
+            this.nested = new Nested(value);
+        }
+
+        public int getId() {
+            return id;
+        }
+
+        public void setId(int id) {
+            this.id = id;
+        }
+
+        public Nested getNested() {
+            return nested;
+        }
+
+        @Override
+        public String toString() {
+            return "Container [id=" + id + ", nested=" + nested + "]";
+        }
+
+
+        protected class Nested {
+            private String value;
+
+            public Nested(String val) {
+                value = val;
+            }
+
+            public String getValue() {
+                return value;
+            }
+
+            @Override
+            public String toString() {
+                return "Nested [value=" + value + "]";
+            }
+        }
+    }
+}
diff --git a/gson/src/test/java/org/onap/policy/common/gson/internal/AdapterTest.java b/gson/src/test/java/org/onap/policy/common/gson/internal/AdapterTest.java
index fcb0d9ad..04f37164 100644
--- a/gson/src/test/java/org/onap/policy/common/gson/internal/AdapterTest.java
+++ b/gson/src/test/java/org/onap/policy/common/gson/internal/AdapterTest.java
@@ -140,7 +140,7 @@ public class AdapterTest {
 
         Method getter = mget("getMyList");
 
-        Adapter aget = new Adapter(gson, getter, true, getter.getReturnType());
+        Adapter aget = new Adapter(gson, getter, getter.getReturnType());
 
         dataAdapter.reset();
         JsonElement tree = aget.toJsonTree(listField);
@@ -148,7 +148,7 @@ public class AdapterTest {
         assertEquals(DataAdapterFactory.ENCODED_LIST, tree.toString());
 
         Method setter = AdapterTest.class.getDeclaredMethod("setMyList", List.class);
-        Adapter aset = new Adapter(gson, setter, true, setter.getGenericParameterTypes()[0]);
+        Adapter aset = new Adapter(gson, setter, setter.getGenericParameterTypes()[0]);
 
         dataAdapter.reset();
         @SuppressWarnings("unchecked")
@@ -168,7 +168,7 @@ public class AdapterTest {
 
 
         // test getter
-        adapter = new Adapter(gson, mget(GET_VALUE_NAME), true, String.class);
+        adapter = new Adapter(gson, mget(GET_VALUE_NAME), String.class);
 
         assertEquals(VALUE_NAME, adapter.getPropName());
         assertEquals(MY_NAME + ".getValue", adapter.getFullName());
@@ -177,7 +177,7 @@ public class AdapterTest {
 
 
         // test setter
-        adapter = new Adapter(gson, mset("setValue"), false, String.class);
+        adapter = new Adapter(gson, mset("setValue"), String.class);
 
         assertEquals(VALUE_NAME, adapter.getPropName());
         assertEquals(MY_NAME + ".setValue", adapter.getFullName());
diff --git a/gson/src/test/java/org/onap/policy/common/gson/internal/AnyGetterSerializerTest.java b/gson/src/test/java/org/onap/policy/common/gson/internal/AnyGetterSerializerTest.java
new file mode 100644
index 00000000..75128420
--- /dev/null
+++ b/gson/src/test/java/org/onap/policy/common/gson/internal/AnyGetterSerializerTest.java
@@ -0,0 +1,134 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.gson.internal;
+
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParseException;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import org.junit.Before;
+import org.junit.Test;
+import org.onap.policy.common.gson.JacksonExclusionStrategy;
+import org.onap.policy.common.gson.internal.AnyGetterSerializer;
+import org.onap.policy.common.gson.internal.DataAdapterFactory.Data;
+
+public class AnyGetterSerializerTest {
+
+    private static DataAdapterFactory dataAdapter = new DataAdapterFactory();
+
+    private static Gson gson = new GsonBuilder().registerTypeAdapterFactory(dataAdapter)
+                    .setExclusionStrategies(new JacksonExclusionStrategy()).create();
+
+    private Set<String> set;
+    private AnyGetterSerializer ser;
+
+    /**
+     * Set up.
+     *
+     * @throws Exception if an error occurs
+     */
+    @Before
+    public void setUp() throws Exception {
+        set = new HashSet<>(Arrays.asList("id", "value"));
+        ser = new AnyGetterSerializer(gson, set, MapData.class.getDeclaredMethod("getTheMap"));
+    }
+
+    @Test
+    public void testAddToTree_testCopyLiftedItems() throws Exception {
+        JsonObject tree = new JsonObject();
+        tree.addProperty("hello", "world");
+
+        MapData data = new MapData();
+
+        data.map = DataAdapterFactory.makeMap();
+
+        // this should not be copied because it is in the "set"
+        data.map.put("value", Arrays.asList(new Data(1000)));
+
+        dataAdapter.reset();
+        JsonObject tree2 = tree.deepCopy();
+        ser.addToTree(data, tree2);
+
+        assertTrue(dataAdapter.isDataWritten());
+
+        DataAdapterFactory.addToObject(tree);
+
+        assertEquals(tree.toString(), tree2.toString());
+    }
+
+    @Test
+    public void testAddToTree_NullMap() throws Exception {
+        JsonObject tree = new JsonObject();
+        tree.addProperty("hello", "world");
+
+        MapData data = new MapData();
+
+        // leave "map" unset
+
+        JsonObject tree2 = tree.deepCopy();
+        ser.addToTree(data, tree2);
+
+        assertEquals(tree.toString(), tree2.toString());
+    }
+
+    @Test
+    public void testAddToTree_NotAnObject() throws Exception {
+        ser = new AnyGetterSerializer(gson, set, NotAnObject.class.getDeclaredMethod("getNonMap"));
+
+        JsonObject tree = new JsonObject();
+
+        NotAnObject data = new NotAnObject();
+        data.text = "bye bye";
+
+        assertThatThrownBy(() -> ser.addToTree(data, tree)).isInstanceOf(JsonParseException.class)
+                        .hasMessage(AnyGetterSerializer.NOT_AN_OBJECT_ERR + NotAnObject.class.getName() + ".getNonMap");
+    }
+
+    public static class MapData {
+        protected int id;
+        protected String value;
+        protected Map<String, List<Data>> map;
+
+        protected Map<String, List<Data>> getTheMap() {
+            return map;
+        }
+    }
+
+    /**
+     * The "lifted" property is not a JsonObject so it should throw an exception.
+     */
+    public static class NotAnObject {
+        protected String text;
+
+        public String getNonMap() {
+            return text;
+        }
+    }
+}
diff --git a/gson/src/test/java/org/onap/policy/common/gson/internal/AnySetterDeserializerTest.java b/gson/src/test/java/org/onap/policy/common/gson/internal/AnySetterDeserializerTest.java
new file mode 100644
index 00000000..b180605e
--- /dev/null
+++ b/gson/src/test/java/org/onap/policy/common/gson/internal/AnySetterDeserializerTest.java
@@ -0,0 +1,94 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.gson.internal;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonObject;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+import org.junit.Before;
+import org.junit.Test;
+import org.onap.policy.common.gson.JacksonExclusionStrategy;
+import org.onap.policy.common.gson.internal.AnySetterDeserializer;
+import org.onap.policy.common.gson.internal.DataAdapterFactory.Data;
+
+public class AnySetterDeserializerTest {
+
+    private static DataAdapterFactory dataAdapter = new DataAdapterFactory();
+
+    private static Gson gson = new GsonBuilder().registerTypeAdapterFactory(dataAdapter)
+                    .setExclusionStrategies(new JacksonExclusionStrategy()).create();
+
+    private Set<String> set;
+    private AnySetterDeserializer deser;
+
+    /**
+     * Set up.
+     *
+     * @throws Exception if an error occurs
+     */
+    @Before
+    public void setUp() throws Exception {
+        set = new HashSet<>(Arrays.asList("id", "value"));
+        deser = new AnySetterDeserializer(gson, set,
+                        MapData.class.getDeclaredMethod("setItem", String.class, List.class));
+    }
+
+    @Test
+    public void testAnySetterDeserializer() {
+        JsonObject json = new JsonObject();
+
+        // these should not be copied
+        json.addProperty("id", 10);
+        json.addProperty("value", "the-value");
+
+        // these should be copied
+        DataAdapterFactory.addToObject(json);
+
+        MapData data = new MapData();
+        data.map = new TreeMap<>();
+
+        dataAdapter.reset();
+        deser.getFromTree(json, data);
+
+        assertTrue(dataAdapter.isDataRead());
+        assertNotNull(data.map);
+        assertEquals(DataAdapterFactory.makeMap().toString(), data.map.toString());
+    }
+
+    public static class MapData {
+        protected Map<String, List<Data>> map;
+
+        protected void setItem(String key, List<Data> value) {
+            map.put(key, value);
+        }
+    }
+
+}
diff --git a/gson/src/test/java/org/onap/policy/common/gson/internal/LifterTest.java b/gson/src/test/java/org/onap/policy/common/gson/internal/LifterTest.java
new file mode 100644
index 00000000..55a3b674
--- /dev/null
+++ b/gson/src/test/java/org/onap/policy/common/gson/internal/LifterTest.java
@@ -0,0 +1,55 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.gson.internal;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import com.google.gson.Gson;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
+import org.junit.Test;
+import org.onap.policy.common.gson.internal.Lifter;
+
+public class LifterTest {
+
+    private static Gson gson = new Gson();
+
+    @Test
+    public void testLifter_testShouldLift() throws Exception {
+        Set<String> set = new HashSet<>(Arrays.asList("abc", "def"));
+        Lifter lifter = new Lifter(gson, set, LifterTest.class.getDeclaredMethod("getValue"), String.class);
+
+        // should not lift these
+        assertFalse(lifter.shouldLift("abc"));
+        assertFalse(lifter.shouldLift("def"));
+
+        // should lift anything else
+        assertTrue(lifter.shouldLift("hello"));
+        assertTrue(lifter.shouldLift("world"));
+    }
+
+    public String getValue() {
+        return "";
+    }
+
+}
diff --git a/gson/src/test/java/org/onap/policy/common/gson/internal/MethodAdapterTest.java b/gson/src/test/java/org/onap/policy/common/gson/internal/MethodAdapterTest.java
new file mode 100644
index 00000000..9f39e3ce
--- /dev/null
+++ b/gson/src/test/java/org/onap/policy/common/gson/internal/MethodAdapterTest.java
@@ -0,0 +1,58 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.gson.internal;
+
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.junit.Assert.assertEquals;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonParseException;
+import org.junit.Test;
+import org.onap.policy.common.gson.internal.MethodAdapter;
+
+public class MethodAdapterTest {
+    private static final Gson gson = new Gson();
+
+    private String saved;
+
+    @Test
+    public void testMethodAdapter_testInvoke() throws Exception {
+        MethodAdapter adapter =
+                        new MethodAdapter(gson, MethodAdapterTest.class.getDeclaredMethod("getValue"), String.class);
+        assertEquals("hello", adapter.invoke(this));
+
+        MethodAdapter adapter2 = new MethodAdapter(gson,
+                        MethodAdapterTest.class.getDeclaredMethod("setValue", String.class), String.class);
+        adapter2.invoke(this, "world");
+        assertEquals("world", saved);
+
+        assertThatThrownBy(() -> adapter2.invoke(this, 100)).isInstanceOf(JsonParseException.class)
+                        .hasMessage(MethodAdapter.INVOKE_ERR + MethodAdapterTest.class.getName() + ".setValue");
+    }
+
+    public String getValue() {
+        return "hello";
+    }
+
+    public void setValue(String val) {
+        saved = val;
+    }
+}
diff --git a/gson/src/test/java/org/onap/policy/common/gson/internal/MethodDeserializerTest.java b/gson/src/test/java/org/onap/policy/common/gson/internal/MethodDeserializerTest.java
new file mode 100644
index 00000000..338644ae
--- /dev/null
+++ b/gson/src/test/java/org/onap/policy/common/gson/internal/MethodDeserializerTest.java
@@ -0,0 +1,100 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.gson.internal;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonNull;
+import com.google.gson.JsonObject;
+import java.util.List;
+import org.junit.Test;
+import org.onap.policy.common.gson.JacksonExclusionStrategy;
+import org.onap.policy.common.gson.internal.DataAdapterFactory.Data;
+import org.onap.policy.common.gson.internal.MethodDeserializer;
+
+public class MethodDeserializerTest {
+    private static final String PROP_NAME = "text";
+    private static final String METHOD_NAME = "setText";
+    private static final String INITIAL_VALUE = "initial value";
+    private static final String NEW_VALUE = "new value";
+
+    private static DataAdapterFactory dataAdapter = new DataAdapterFactory();
+
+    private static Gson gson = new GsonBuilder().registerTypeAdapterFactory(dataAdapter)
+                    .setExclusionStrategies(new JacksonExclusionStrategy()).create();
+
+    private MethodDeserializer deser;
+
+    private String text;
+
+    private List<Data> listField;
+
+    @Test
+    public void testGetFromTree() throws Exception {
+        deser = new MethodDeserializer(gson, MethodDeserializerTest.class.getDeclaredMethod(METHOD_NAME, String.class));
+
+        // non-existent value - should not overwrite
+        text = INITIAL_VALUE;
+        JsonObject json = new JsonObject();
+        deser.getFromTree(json, this);
+        assertEquals(INITIAL_VALUE, text);
+
+        // null value - should not overwrite
+        text = INITIAL_VALUE;
+        json.add(PROP_NAME, JsonNull.INSTANCE);
+        deser.getFromTree(json, this);
+        assertEquals(INITIAL_VALUE, text);
+
+        // has a value - should store it
+        text = INITIAL_VALUE;
+        json.addProperty(PROP_NAME, NEW_VALUE);
+        deser.getFromTree(json, this);
+        assertEquals(NEW_VALUE, text);
+
+        /*
+         * check list field
+         */
+        deser = new MethodDeserializer(gson, MethodDeserializerTest.class.getDeclaredMethod("setTheList", List.class));
+
+        json = new JsonObject();
+        json.add("theList", DataAdapterFactory.makeArray());
+
+        dataAdapter.reset();
+        listField = null;
+        deser.getFromTree(json, this);
+
+        assertTrue(dataAdapter.isDataRead());
+        assertNotNull(listField);
+        assertEquals(DataAdapterFactory.makeList().toString(), listField.toString());
+    }
+
+    protected void setText(String text) {
+        this.text = text;
+    }
+
+    protected void setTheList(List<Data> lst) {
+        listField = lst;
+    }
+}
diff --git a/gson/src/test/java/org/onap/policy/common/gson/internal/MethodSerializerTest.java b/gson/src/test/java/org/onap/policy/common/gson/internal/MethodSerializerTest.java
new file mode 100644
index 00000000..586bf54d
--- /dev/null
+++ b/gson/src/test/java/org/onap/policy/common/gson/internal/MethodSerializerTest.java
@@ -0,0 +1,88 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.gson.internal;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import java.util.List;
+import org.junit.Test;
+import org.onap.policy.common.gson.JacksonExclusionStrategy;
+import org.onap.policy.common.gson.internal.DataAdapterFactory.Data;
+import org.onap.policy.common.gson.internal.MethodSerializer;
+
+public class MethodSerializerTest {
+    private static final String PROP_NAME = "text";
+    private static final String METHOD_NAME = "getText";
+
+    private static DataAdapterFactory dataAdapter = new DataAdapterFactory();
+
+    private static Gson gson = new GsonBuilder().registerTypeAdapterFactory(dataAdapter)
+                    .setExclusionStrategies(new JacksonExclusionStrategy()).create();
+
+    private MethodSerializer ser;
+
+    private String text;
+
+    private List<Data> listField;
+
+    @Test
+    public void testAddToTree() throws Exception {
+        ser = new MethodSerializer(gson, MethodSerializerTest.class.getDeclaredMethod(METHOD_NAME));
+
+        // serialize null value first
+        text = null;
+
+        JsonObject json = new JsonObject();
+        ser.addToTree(this, json);
+        assertTrue(json.get(PROP_NAME).isJsonNull());
+
+        // serialize an actual value
+        text = "hello";
+        ser.addToTree(this, json);
+        assertEquals("hello", json.get(PROP_NAME).getAsString());
+
+        /*
+         * check list field
+         */
+        listField = DataAdapterFactory.makeList();
+
+        ser = new MethodSerializer(gson, MethodSerializerTest.class.getDeclaredMethod("getTheList"));
+
+        dataAdapter.reset();
+        JsonElement tree = ser.toJsonTree(listField);
+
+        assertTrue(dataAdapter.isDataWritten());
+        assertEquals(DataAdapterFactory.ENCODED_LIST, tree.toString());
+    }
+
+    protected String getText() {
+        return text;
+    }
+
+    protected List<Data> getTheList() {
+        return listField;
+    }
+}