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.InstanceCreator;
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 com.google.gson.reflect.TypeToken;

import junit.framework.TestCase;

import java.lang.reflect.Type;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

/**
 * 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 testCustomTypeAdapterDoesNotAppliesToSubClasses() {
    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);
    assertTrue(json.contains("derivedValue"));    
  }
  
  public void testCustomTypeAdapterAppliesToSubClassesSerializedAsBaseClass() {
    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 {
    @SuppressWarnings("unused")
    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);
    }
  }
  
  public void testCustomSerializerForLong() {
    final ClassWithBooleanField customSerializerInvoked = new ClassWithBooleanField();
    customSerializerInvoked.value = false;
    Gson gson = new GsonBuilder().registerTypeAdapter(Long.class, new JsonSerializer<Long>() {
      public JsonElement serialize(Long src, Type typeOfSrc, JsonSerializationContext context) {
        customSerializerInvoked.value = true;
        return new JsonPrimitive(src);
      }      
    }).serializeNulls().create();
    ClassWithWrapperLongField src = new ClassWithWrapperLongField();
    String json = gson.toJson(src);
    assertTrue(json.contains("\"value\":null"));
    assertFalse(customSerializerInvoked.value);
    
    customSerializerInvoked.value = false;
    src.value = 10L;
    json = gson.toJson(src);
    assertTrue(json.contains("\"value\":10"));
    assertTrue(customSerializerInvoked.value);
  }
  
  public void testCustomDeserializerForLong() {
    final ClassWithBooleanField customDeserializerInvoked = new ClassWithBooleanField();
    customDeserializerInvoked.value = false;
    Gson gson = new GsonBuilder().registerTypeAdapter(Long.class, new JsonDeserializer<Long>() {
      public Long deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
          throws JsonParseException {
        customDeserializerInvoked.value = true;
        if (json == null || json.isJsonNull()) {
          return null;
        } else {
          Number number = json.getAsJsonPrimitive().getAsNumber();
          return number == null ? null : number.longValue();
        }
      }      
    }).create();
    String json = "{'value':null}";
    ClassWithWrapperLongField target = gson.fromJson(json, ClassWithWrapperLongField.class);
    assertNull(target.value);
    assertFalse(customDeserializerInvoked.value);
    
    customDeserializerInvoked.value = false;
    json = "{'value':10}";
    target = gson.fromJson(json, ClassWithWrapperLongField.class);
    assertEquals(10L, target.value.longValue());
    assertTrue(customDeserializerInvoked.value);
  }
  
  private static class ClassWithWrapperLongField {
    Long value;
  }
  
  private static class ClassWithBooleanField {
    Boolean value;
  }
  
  public void testCustomByteArraySerializer() {
    Gson gson = new GsonBuilder().registerTypeAdapter(byte[].class, new JsonSerializer<byte[]>() {
      public JsonElement serialize(byte[] src, Type typeOfSrc, JsonSerializationContext context) {
        StringBuilder sb = new StringBuilder(src.length);
        for (byte b : src) {
          sb.append(b);
        }
        return new JsonPrimitive(sb.toString());
      }      
    }).create();
    byte[] data = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
    String json = gson.toJson(data);
    assertEquals("\"0123456789\"", json);
  }
  
  public void testCustomByteArrayDeserializerAndInstanceCreator() {
    GsonBuilder gsonBuilder = new GsonBuilder().registerTypeAdapter(byte[].class, 
        new JsonDeserializer<byte[]>() {
      public byte[] deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
          throws JsonParseException {
        String str = json.getAsString();
        byte[] data = new byte[str.length()];
        for (int i = 0; i < data.length; ++i) {
          data[i] = Byte.parseByte(""+str.charAt(i));
        }
        return data;
      }      
    });
    Gson gson = gsonBuilder.create();
    String json = "'0123456789'";
    byte[] actual = gson.fromJson(json, byte[].class);
    byte[] expected = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
    for (int i = 0; i < actual.length; ++i) {
      assertEquals(expected[i], actual[i]);
    }
  }
  
  private static class StringHolder {
    String part1;
    String part2;

    public StringHolder(String string) {
      String[] parts = string.split(":");
      part1 = parts[0];
      part2 = parts[1];
    }
    public StringHolder(String part1, String part2) {
      this.part1 = part1;
      this.part2 = part2;
    }
  }
  
  private static class StringHolderTypeAdapter implements JsonSerializer<StringHolder>, 
      JsonDeserializer<StringHolder>, InstanceCreator<StringHolder> {

    public StringHolder createInstance(Type type) {
      //Fill up with objects that will be thrown away
      return new StringHolder("unknown:thing");
    }

    public StringHolder deserialize(JsonElement src, Type type, 
        JsonDeserializationContext context) {
      return new StringHolder(src.getAsString());
    }

    public JsonElement serialize(StringHolder src, Type typeOfSrc, 
        JsonSerializationContext context) {
      String contents = src.part1 + ':' + src.part2;
      return new JsonPrimitive(contents);
    }
  }
  
  // Test created from Issue 70
  public void testCustomAdapterInvokedForCollectionElementSerializationWithType() {
    Gson gson = new GsonBuilder()
      .registerTypeAdapter(StringHolder.class, new StringHolderTypeAdapter())
      .create();
    Type setType = new TypeToken<Set<StringHolder>>() {}.getType();
    StringHolder holder = new StringHolder("Jacob", "Tomaw");
    Set<StringHolder> setOfHolders = new HashSet<StringHolder>();
    setOfHolders.add(holder);
    String json = gson.toJson(setOfHolders, setType);
    assertTrue(json.contains("Jacob:Tomaw"));
  }

  // Test created from Issue 70
  public void testCustomAdapterInvokedForCollectionElementSerialization() {
    Gson gson = new GsonBuilder()
      .registerTypeAdapter(StringHolder.class, new StringHolderTypeAdapter())
      .create();
    StringHolder holder = new StringHolder("Jacob", "Tomaw");
    Set<StringHolder> setOfHolders = new HashSet<StringHolder>();
    setOfHolders.add(holder);
    String json = gson.toJson(setOfHolders);
    assertTrue(json.contains("Jacob:Tomaw"));
  }

  // Test created from Issue 70
  public void testCustomAdapterInvokedForCollectionElementDeserialization() {
    Gson gson = new GsonBuilder()
      .registerTypeAdapter(StringHolder.class, new StringHolderTypeAdapter())
      .create();
    Type setType = new TypeToken<Set<StringHolder>>() {}.getType();
    Set<StringHolder> setOfHolders = gson.fromJson("['Jacob:Tomaw']", setType);
    assertEquals(1, setOfHolders.size());
    StringHolder foo = setOfHolders.iterator().next();
    assertEquals("Jacob", foo.part1);
    assertEquals("Tomaw", foo.part2);
  }
  
  // Test created from Issue 70
  public void testCustomAdapterInvokedForMapElementSerializationWithType() {
    Gson gson = new GsonBuilder()
      .registerTypeAdapter(StringHolder.class, new StringHolderTypeAdapter())
      .create();
    Type mapType = new TypeToken<Map<String,StringHolder>>() {}.getType();
    StringHolder holder = new StringHolder("Jacob", "Tomaw");
    Map<String, StringHolder> mapOfHolders = new HashMap<String, StringHolder>();
    mapOfHolders.put("foo", holder);
    String json = gson.toJson(mapOfHolders, mapType);
    assertTrue(json.contains("\"foo\":\"Jacob:Tomaw\""));
  }
  
  // Test created from Issue 70
  public void testCustomAdapterInvokedForMapElementSerialization() {
    Gson gson = new GsonBuilder()
      .registerTypeAdapter(StringHolder.class, new StringHolderTypeAdapter())
      .create();
    StringHolder holder = new StringHolder("Jacob", "Tomaw");
    Map<String, StringHolder> mapOfHolders = new HashMap<String, StringHolder>();
    mapOfHolders.put("foo", holder);
    String json = gson.toJson(mapOfHolders);
    assertTrue(json.contains("\"foo\":\"Jacob:Tomaw\""));
  }

  // Test created from Issue 70
  public void testCustomAdapterInvokedForMapElementDeserialization() {
    Gson gson = new GsonBuilder()
      .registerTypeAdapter(StringHolder.class, new StringHolderTypeAdapter())
      .create();
    Type mapType = new TypeToken<Map<String, StringHolder>>() {}.getType();
    Map<String, StringHolder> mapOfFoo = gson.fromJson("{'foo':'Jacob:Tomaw'}", mapType);
    assertEquals(1, mapOfFoo.size());
    StringHolder foo = mapOfFoo.get("foo");
    assertEquals("Jacob", foo.part1);
    assertEquals("Tomaw", foo.part2);
  }
}