gson-comments/gson/src/test/java/com/google/gson/functional/CustomTypeAdaptersTest.java

/*
 * Copyright (C) 2008 Google Inc.
 *
 * 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.
 */
package com.google.gson.functional;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParseException;
import com.google.gson.JsonPrimitive;
import com.google.gson.JsonSerializationContext;
import com.google.gson.JsonSerializer;
import com.google.gson.common.TestTypes.BagOfPrimitives;
import com.google.gson.common.TestTypes.ClassWithCustomTypeConverter;

import junit.framework.TestCase;

import java.lang.reflect.Type;

/**
 * Functional tests for the support of custom serializer and deserializers.
 *
 * @author Inderjeet Singh
 * @author Joel Leitch
 */
public class CustomTypeAdaptersTest extends TestCase {
  private GsonBuilder builder;

  @Override
  protected void setUp() throws Exception {
    super.setUp();
    builder = new GsonBuilder();
  }

  public void testCustomSerializers() {
    Gson gson = builder.registerTypeAdapter(
        ClassWithCustomTypeConverter.class, new JsonSerializer<ClassWithCustomTypeConverter>() {
      public JsonElement serialize(ClassWithCustomTypeConverter src, Type typeOfSrc,
          JsonSerializationContext context) {
        JsonObject json = new JsonObject();
        json.addProperty("bag", 5);
        json.addProperty("value", 25);
        return json;
      }
    }).create();
    ClassWithCustomTypeConverter target = new ClassWithCustomTypeConverter();
    assertEquals("{\"bag\":5,\"value\":25}", gson.toJson(target));
  }

  public void testCustomDeserializers() {
    Gson gson = new GsonBuilder().registerTypeAdapter(
        ClassWithCustomTypeConverter.class, new JsonDeserializer<ClassWithCustomTypeConverter>() {
      public ClassWithCustomTypeConverter deserialize(JsonElement json, Type typeOfT,
          JsonDeserializationContext context) {
        JsonObject jsonObject = json.getAsJsonObject();
        int value = jsonObject.get("bag").getAsInt();
        return new ClassWithCustomTypeConverter(new BagOfPrimitives(value,
            value, false, ""), value);
      }
    }).create();
    String json = "{\"bag\":5,\"value\":25}";
    ClassWithCustomTypeConverter target = gson.fromJson(json, ClassWithCustomTypeConverter.class);
    assertEquals(5, target.getBag().getIntValue());
  }
  
  public void disable_testCustomSerializersOfSelf() {
    Gson gson = createGsonObjectWithFooTypeAdapter();
    Gson basicGson = new Gson();
    Foo newFooObject = new Foo(1, 2L);
    String jsonFromCustomSerializer = gson.toJson(newFooObject);
    String jsonFromGson = basicGson.toJson(newFooObject);
    
    assertEquals(jsonFromGson, jsonFromCustomSerializer);
  }

  public void disable_testCustomDeserializersOfSelf() {
    Gson gson = createGsonObjectWithFooTypeAdapter();
    Gson basicGson = new Gson();
    Foo expectedFoo = new Foo(1, 2L);
    String json = basicGson.toJson(expectedFoo);
    Foo newFooObject = gson.fromJson(json, Foo.class);
    
    assertEquals(expectedFoo.key, newFooObject.key);
    assertEquals(expectedFoo.value, newFooObject.value);
  }

  public void testCustomNestedSerializers() {
    Gson gson = new GsonBuilder().registerTypeAdapter(
        BagOfPrimitives.class, new JsonSerializer<BagOfPrimitives>() {
      public JsonElement serialize(BagOfPrimitives src, Type typeOfSrc,
          JsonSerializationContext context) {
        return new JsonPrimitive(6);
      }
    }).create();
    ClassWithCustomTypeConverter target = new ClassWithCustomTypeConverter();
    assertEquals("{\"bag\":6,\"value\":10}", gson.toJson(target));
  }

  public void testCustomNestedDeserializers() {
    Gson gson = new GsonBuilder().registerTypeAdapter(
        BagOfPrimitives.class, new JsonDeserializer<BagOfPrimitives>() {
      public BagOfPrimitives deserialize(JsonElement json, Type typeOfT,
          JsonDeserializationContext context) throws JsonParseException {
        int value = json.getAsInt();
        return new BagOfPrimitives(value, value, false, "");
      }
    }).create();
    String json = "{\"bag\":7,\"value\":25}";
    ClassWithCustomTypeConverter target = gson.fromJson(json, ClassWithCustomTypeConverter.class);
    assertEquals(7, target.getBag().getIntValue());
  }
  
  public void testCustomTypeAdapterAppliesToSubClasses() {
    Gson gson = new GsonBuilder().registerTypeAdapter(Base.class, new JsonSerializer<Base> () {
      public JsonElement serialize(Base src, Type typeOfSrc, JsonSerializationContext context) {
        JsonObject json = new JsonObject();
        json.addProperty("value", src.baseValue);
        return json;
      }          
    }).create();
    Base b = new Base();
    String json = gson.toJson(b);
    assertTrue(json.contains("value"));    
    b = new Derived();
    json = gson.toJson(b, Base.class);
    assertTrue(json.contains("value"));    
    assertFalse(json.contains("derivedValue"));
  }
  
  private static class Base {
    int baseValue = 2;
  }
  
  private static class Derived extends Base {
    int derivedValue = 3;
  }
  
  
  private Gson createGsonObjectWithFooTypeAdapter() {
    return new GsonBuilder().registerTypeAdapter(Foo.class, new FooTypeAdapter()).create();
  }
  
  public static class Foo {
    private final int key;
    private final long value;
    
    public Foo() {
      this(0, 0L);
    }

    public Foo(int key, long value) {
      this.key = key;
      this.value = value;
    }
  }
  
  public static class FooTypeAdapter implements JsonSerializer<Foo>, JsonDeserializer<Foo> {
    public Foo deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
        throws JsonParseException {
      return context.deserialize(json, typeOfT);
    }

    public JsonElement serialize(Foo src, Type typeOfSrc, JsonSerializationContext context) {
      return context.serialize(src, typeOfSrc);
    }
  }
}