NullObjectAndFieldTest.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 static com.google.common.truth.Truth.assertThat;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonNull;
import com.google.gson.JsonObject;
import com.google.gson.JsonSerializationContext;
import com.google.gson.JsonSerializer;
import com.google.gson.common.TestTypes.BagOfPrimitives;
import com.google.gson.common.TestTypes.ClassWithObjects;
import java.lang.reflect.Type;
import java.util.Collection;
import org.junit.Before;
import org.junit.Test;
/**
* Functional tests for the different cases for serializing (or ignoring) null fields and object.
*
* @author Inderjeet Singh
* @author Joel Leitch
*/
public class NullObjectAndFieldTest {
private GsonBuilder gsonBuilder;
@Before
public void setUp() throws Exception {
gsonBuilder = new GsonBuilder().serializeNulls();
}
@Test
public void testTopLevelNullObjectSerialization() {
Gson gson = gsonBuilder.create();
String actual = gson.toJson(null);
assertThat(actual).isEqualTo("null");
actual = gson.toJson(null, String.class);
assertThat(actual).isEqualTo("null");
}
@Test
public void testTopLevelNullObjectDeserialization() {
Gson gson = gsonBuilder.create();
String actual = gson.fromJson("null", String.class);
assertThat(actual).isNull();
}
@Test
public void testExplicitSerializationOfNulls() {
Gson gson = gsonBuilder.create();
ClassWithObjects target = new ClassWithObjects(null);
String actual = gson.toJson(target);
String expected = "{\"bag\":null}";
assertThat(actual).isEqualTo(expected);
}
@Test
public void testExplicitDeserializationOfNulls() {
Gson gson = gsonBuilder.create();
ClassWithObjects target = gson.fromJson("{\"bag\":null}", ClassWithObjects.class);
assertThat(target.bag).isNull();
}
@Test
public void testExplicitSerializationOfNullArrayMembers() {
Gson gson = gsonBuilder.create();
ClassWithMembers target = new ClassWithMembers();
String json = gson.toJson(target);
assertThat(json).contains("\"array\":null");
}
/** Added to verify http://code.google.com/p/google-gson/issues/detail?id=68 */
@Test
public void testNullWrappedPrimitiveMemberSerialization() {
Gson gson = gsonBuilder.serializeNulls().create();
ClassWithNullWrappedPrimitive target = new ClassWithNullWrappedPrimitive();
String json = gson.toJson(target);
assertThat(json).contains("\"value\":null");
}
/** Added to verify http://code.google.com/p/google-gson/issues/detail?id=68 */
@Test
public void testNullWrappedPrimitiveMemberDeserialization() {
Gson gson = gsonBuilder.create();
String json = "{'value':null}";
ClassWithNullWrappedPrimitive target = gson.fromJson(json, ClassWithNullWrappedPrimitive.class);
assertThat(target.value).isNull();
}
@Test
public void testExplicitSerializationOfNullCollectionMembers() {
Gson gson = gsonBuilder.create();
ClassWithMembers target = new ClassWithMembers();
String json = gson.toJson(target);
assertThat(json).contains("\"col\":null");
}
@Test
public void testExplicitSerializationOfNullStringMembers() {
Gson gson = gsonBuilder.create();
ClassWithMembers target = new ClassWithMembers();
String json = gson.toJson(target);
assertThat(json).contains("\"str\":null");
}
@Test
public void testCustomSerializationOfNulls() {
gsonBuilder.registerTypeAdapter(ClassWithObjects.class, new ClassWithObjectsSerializer());
Gson gson = gsonBuilder.create();
ClassWithObjects target = new ClassWithObjects(new BagOfPrimitives());
String actual = gson.toJson(target);
String expected = "{\"bag\":null}";
assertThat(actual).isEqualTo(expected);
}
@Test
public void testPrintPrintingObjectWithNulls() {
gsonBuilder = new GsonBuilder();
Gson gson = gsonBuilder.create();
String result = gson.toJson(new ClassWithMembers());
assertThat(result).isEqualTo("{}");
gson = gsonBuilder.serializeNulls().create();
result = gson.toJson(new ClassWithMembers());
assertThat(result).contains("\"str\":null");
}
@Test
public void testPrintPrintingArraysWithNulls() {
gsonBuilder = new GsonBuilder();
Gson gson = gsonBuilder.create();
String result = gson.toJson(new String[] {"1", null, "3"});
assertThat(result).isEqualTo("[\"1\",null,\"3\"]");
gson = gsonBuilder.serializeNulls().create();
result = gson.toJson(new String[] {"1", null, "3"});
assertThat(result).isEqualTo("[\"1\",null,\"3\"]");
}
// test for issue 389
@Test
public void testAbsentJsonElementsAreSetToNull() {
Gson gson = new Gson();
ClassWithInitializedMembers target =
gson.fromJson("{array:[1,2,3]}", ClassWithInitializedMembers.class);
assertThat(target.array).hasLength(3);
assertThat(target.array[1]).isEqualTo(2);
assertThat(target.str1).isEqualTo(ClassWithInitializedMembers.MY_STRING_DEFAULT);
assertThat(target.str2).isNull();
assertThat(target.int1).isEqualTo(ClassWithInitializedMembers.MY_INT_DEFAULT);
// test the default value of a primitive int field per JVM spec
assertThat(target.int2).isEqualTo(0);
assertThat(target.bool1).isEqualTo(ClassWithInitializedMembers.MY_BOOLEAN_DEFAULT);
// test the default value of a primitive boolean field per JVM spec
assertThat(target.bool2).isFalse();
}
public static class ClassWithInitializedMembers {
// Using a mix of no-args constructor and field initializers
// Also, some fields are initialized and some are not (so initialized per JVM spec)
public static final String MY_STRING_DEFAULT = "string";
private static final int MY_INT_DEFAULT = 2;
private static final boolean MY_BOOLEAN_DEFAULT = true;
int[] array;
String str1;
String str2;
int int1 = MY_INT_DEFAULT;
int int2;
boolean bool1 = MY_BOOLEAN_DEFAULT;
boolean bool2;
public ClassWithInitializedMembers() {
str1 = MY_STRING_DEFAULT;
}
}
private static class ClassWithNullWrappedPrimitive {
private Long value;
}
@SuppressWarnings("unused")
private static class ClassWithMembers {
String str;
int[] array;
Collection<String> col;
}
private static class ClassWithObjectsSerializer implements JsonSerializer<ClassWithObjects> {
@Override
public JsonElement serialize(
ClassWithObjects src, Type typeOfSrc, JsonSerializationContext context) {
JsonObject obj = new JsonObject();
obj.add("bag", JsonNull.INSTANCE);
return obj;
}
}
@Test
public void testExplicitNullSetsFieldToNullDuringDeserialization() {
Gson gson = new Gson();
String json = "{value:null}";
ObjectWithField obj = gson.fromJson(json, ObjectWithField.class);
assertThat(obj.value).isNull();
}
@Test
public void testCustomTypeAdapterPassesNullSerialization() {
Gson gson =
new GsonBuilder()
.registerTypeAdapter(
ObjectWithField.class,
(JsonSerializer<ObjectWithField>)
(src, typeOfSrc, context) -> context.serialize(null))
.create();
ObjectWithField target = new ObjectWithField();
target.value = "value1";
String json = gson.toJson(target);
assertThat(json).doesNotContain("value1");
}
@Test
public void testCustomTypeAdapterPassesNullDeserialization() {
Gson gson =
new GsonBuilder()
.registerTypeAdapter(
ObjectWithField.class,
(JsonDeserializer<ObjectWithField>)
(json, type, context) -> context.deserialize(null, type))
.create();
String json = "{value:'value1'}";
ObjectWithField target = gson.fromJson(json, ObjectWithField.class);
assertThat(target).isNull();
}
private static class ObjectWithField {
String value = "";
}
}