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Add tests checking GsonBuilder not affecting existing Gson instances #1815

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merged 2 commits into from Aug 22, 2022
Merged

Add tests checking GsonBuilder not affecting existing Gson instances #1815

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541f8ab
Fix changes to GsonBuilder affecting existing Gson instances
Marcono1234 Nov 6, 2020
0675bb2
Merge branch 'master' into marcono1234/gsonbuilder-reuse
Marcono1234 Aug 22, 2022
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131 changes: 111 additions & 20 deletions gson/src/test/java/com/google/gson/GsonBuilderTest.java
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Expand Up @@ -16,14 +16,14 @@

package com.google.gson;

import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonWriter;
import java.io.IOException;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.lang.reflect.Type;

import junit.framework.TestCase;

import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonWriter;

/**
* Unit tests for {@link GsonBuilder}.
*
Expand All @@ -41,8 +41,99 @@ public class GsonBuilderTest extends TestCase {

public void testCreatingMoreThanOnce() {
GsonBuilder builder = new GsonBuilder();
builder.create();
builder.create();
Gson gson = builder.create();
assertNotNull(gson);
assertNotNull(builder.create());

builder.setFieldNamingStrategy(new FieldNamingStrategy() {
@Override public String translateName(Field f) {
return "test";
}
});

Gson otherGson = builder.create();
assertNotNull(otherGson);
// Should be different instances because builder has been modified in the meantime
assertNotSame(gson, otherGson);
}

/**
* Gson instances should not be affected by subsequent modification of GsonBuilder
* which created them.
*/
public void testModificationAfterCreate() {
GsonBuilder gsonBuilder = new GsonBuilder();
Gson gson = gsonBuilder.create();

// Modifications of `gsonBuilder` should not affect `gson` object
gsonBuilder.registerTypeAdapter(CustomClass1.class, new TypeAdapter<CustomClass1>() {
@Override public CustomClass1 read(JsonReader in) throws IOException {
throw new UnsupportedOperationException();
}

@Override public void write(JsonWriter out, CustomClass1 value) throws IOException {
out.value("custom-adapter");
}
});
gsonBuilder.registerTypeHierarchyAdapter(CustomClass2.class, new JsonSerializer<CustomClass2>() {
@Override public JsonElement serialize(CustomClass2 src, Type typeOfSrc, JsonSerializationContext context) {
return new JsonPrimitive("custom-hierarchy-adapter");
}
});
gsonBuilder.registerTypeAdapter(CustomClass3.class, new InstanceCreator<CustomClass3>() {
@Override public CustomClass3 createInstance(Type type) {
return new CustomClass3("custom-instance");
}
});

assertDefaultGson(gson);
// New GsonBuilder created from `gson` should not have been affected by changes
// to `gsonBuilder` either
assertDefaultGson(gson.newBuilder().create());

// New Gson instance from modified GsonBuilder should be affected by changes
assertCustomGson(gsonBuilder.create());
}

private static void assertDefaultGson(Gson gson) {
// Should use default reflective adapter
String json1 = gson.toJson(new CustomClass1());
assertEquals("{}", json1);

// Should use default reflective adapter
String json2 = gson.toJson(new CustomClass2());
assertEquals("{}", json2);

// Should use default instance creator
CustomClass3 customClass3 = gson.fromJson("{}", CustomClass3.class);
assertEquals(CustomClass3.NO_ARG_CONSTRUCTOR_VALUE, customClass3.s);
}

private static void assertCustomGson(Gson gson) {
String json1 = gson.toJson(new CustomClass1());
assertEquals("\"custom-adapter\"", json1);

String json2 = gson.toJson(new CustomClass2());
assertEquals("\"custom-hierarchy-adapter\"", json2);

CustomClass3 customClass3 = gson.fromJson("{}", CustomClass3.class);
assertEquals("custom-instance", customClass3.s);
}

static class CustomClass1 { }
static class CustomClass2 { }
static class CustomClass3 {
static final String NO_ARG_CONSTRUCTOR_VALUE = "default instance";

final String s;

public CustomClass3(String s) {
this.s = s;
}

public CustomClass3() {
this(NO_ARG_CONSTRUCTOR_VALUE);
}
}

public void testExcludeFieldsWithModifiers() {
Expand All @@ -52,20 +143,6 @@ public void testExcludeFieldsWithModifiers() {
assertEquals("{\"d\":\"d\"}", gson.toJson(new HasModifiers()));
}

public void testRegisterTypeAdapterForCoreType() {
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Moved this down to not be between two test method for GsonBuilder.excludeFieldsWithModifiers.

Type[] types = {
byte.class,
int.class,
double.class,
Short.class,
Long.class,
String.class,
};
for (Type type : types) {
new GsonBuilder().registerTypeAdapter(type, NULL_TYPE_ADAPTER);
}
}

@SuppressWarnings("unused")
static class HasModifiers {
private String a = "a";
Expand All @@ -85,6 +162,20 @@ static class HasTransients {
transient String a = "a";
}

public void testRegisterTypeAdapterForCoreType() {
Type[] types = {
byte.class,
int.class,
double.class,
Short.class,
Long.class,
String.class,
};
for (Type type : types) {
new GsonBuilder().registerTypeAdapter(type, NULL_TYPE_ADAPTER);
}
}

public void testDisableJdkUnsafe() {
Gson gson = new GsonBuilder()
.disableJdkUnsafe()
Expand Down
147 changes: 147 additions & 0 deletions gson/src/test/java/com/google/gson/GsonTest.java
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Expand Up @@ -221,4 +221,151 @@ public void testNewJsonReader_Custom() throws IOException {
assertEquals("test", jsonReader.nextString());
jsonReader.close();
}

/**
* Modifying a GsonBuilder obtained from {@link Gson#newBuilder()} of a
* {@code new Gson()} should not affect the Gson instance it came from.
*/
public void testDefaultGsonNewBuilderModification() {
Gson gson = new Gson();
GsonBuilder gsonBuilder = gson.newBuilder();

// Modifications of `gsonBuilder` should not affect `gson` object
gsonBuilder.registerTypeAdapter(CustomClass1.class, new TypeAdapter<CustomClass1>() {
@Override public CustomClass1 read(JsonReader in) throws IOException {
throw new UnsupportedOperationException();
}

@Override public void write(JsonWriter out, CustomClass1 value) throws IOException {
out.value("custom-adapter");
}
});
gsonBuilder.registerTypeHierarchyAdapter(CustomClass2.class, new JsonSerializer<CustomClass2>() {
@Override public JsonElement serialize(CustomClass2 src, Type typeOfSrc, JsonSerializationContext context) {
return new JsonPrimitive("custom-hierarchy-adapter");
}
});
gsonBuilder.registerTypeAdapter(CustomClass3.class, new InstanceCreator<CustomClass3>() {
@Override public CustomClass3 createInstance(Type type) {
return new CustomClass3("custom-instance");
}
});

assertDefaultGson(gson);
// New GsonBuilder created from `gson` should not have been affected by changes either
assertDefaultGson(gson.newBuilder().create());

// But new Gson instance from `gsonBuilder` should use custom adapters
assertCustomGson(gsonBuilder.create());
}

private static void assertDefaultGson(Gson gson) {
// Should use default reflective adapter
String json1 = gson.toJson(new CustomClass1());
assertEquals("{}", json1);

// Should use default reflective adapter
String json2 = gson.toJson(new CustomClass2());
assertEquals("{}", json2);

// Should use default instance creator
CustomClass3 customClass3 = gson.fromJson("{}", CustomClass3.class);
assertEquals(CustomClass3.NO_ARG_CONSTRUCTOR_VALUE, customClass3.s);
}

/**
* Modifying a GsonBuilder obtained from {@link Gson#newBuilder()} of a custom
* Gson instance (created using a GsonBuilder) should not affect the Gson instance
* it came from.
*/
public void testNewBuilderModification() {
Gson gson = new GsonBuilder()
.registerTypeAdapter(CustomClass1.class, new TypeAdapter<CustomClass1>() {
@Override public CustomClass1 read(JsonReader in) throws IOException {
throw new UnsupportedOperationException();
}

@Override public void write(JsonWriter out, CustomClass1 value) throws IOException {
out.value("custom-adapter");
}
})
.registerTypeHierarchyAdapter(CustomClass2.class, new JsonSerializer<CustomClass2>() {
@Override public JsonElement serialize(CustomClass2 src, Type typeOfSrc, JsonSerializationContext context) {
return new JsonPrimitive("custom-hierarchy-adapter");
}
})
.registerTypeAdapter(CustomClass3.class, new InstanceCreator<CustomClass3>() {
@Override public CustomClass3 createInstance(Type type) {
return new CustomClass3("custom-instance");
}
})
.create();

assertCustomGson(gson);

// Modify `gson.newBuilder()`
GsonBuilder gsonBuilder = gson.newBuilder();
gsonBuilder.registerTypeAdapter(CustomClass1.class, new TypeAdapter<CustomClass1>() {
@Override public CustomClass1 read(JsonReader in) throws IOException {
throw new UnsupportedOperationException();
}

@Override public void write(JsonWriter out, CustomClass1 value) throws IOException {
out.value("overwritten custom-adapter");
}
});
gsonBuilder.registerTypeHierarchyAdapter(CustomClass2.class, new JsonSerializer<CustomClass2>() {
@Override public JsonElement serialize(CustomClass2 src, Type typeOfSrc, JsonSerializationContext context) {
return new JsonPrimitive("overwritten custom-hierarchy-adapter");
}
});
gsonBuilder.registerTypeAdapter(CustomClass3.class, new InstanceCreator<CustomClass3>() {
@Override public CustomClass3 createInstance(Type type) {
return new CustomClass3("overwritten custom-instance");
}
});

// `gson` object should not have been affected by changes to new GsonBuilder
assertCustomGson(gson);
// New GsonBuilder based on `gson` should not have been affected either
assertCustomGson(gson.newBuilder().create());

// But new Gson instance from `gsonBuilder` should be affected by changes
Gson otherGson = gsonBuilder.create();
String json1 = otherGson.toJson(new CustomClass1());
assertEquals("\"overwritten custom-adapter\"", json1);

String json2 = otherGson.toJson(new CustomClass2());
assertEquals("\"overwritten custom-hierarchy-adapter\"", json2);

CustomClass3 customClass3 = otherGson.fromJson("{}", CustomClass3.class);
assertEquals("overwritten custom-instance", customClass3.s);
}

private static void assertCustomGson(Gson gson) {
String json1 = gson.toJson(new CustomClass1());
assertEquals("\"custom-adapter\"", json1);

String json2 = gson.toJson(new CustomClass2());
assertEquals("\"custom-hierarchy-adapter\"", json2);

CustomClass3 customClass3 = gson.fromJson("{}", CustomClass3.class);
assertEquals("custom-instance", customClass3.s);
}

static class CustomClass1 { }
static class CustomClass2 { }
static class CustomClass3 {
static final String NO_ARG_CONSTRUCTOR_VALUE = "default instance";

final String s;

public CustomClass3(String s) {
this.s = s;
}

public CustomClass3() {
this(NO_ARG_CONSTRUCTOR_VALUE);
}
}
}