454 lines
19 KiB
Java
454 lines
19 KiB
Java
/*
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* Copyright (C) 2010 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.gson.reflect;
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import static com.google.common.truth.Truth.assertThat;
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import static org.junit.Assert.assertThrows;
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import java.lang.reflect.GenericArrayType;
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import java.lang.reflect.Method;
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import java.lang.reflect.ParameterizedType;
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import java.lang.reflect.Type;
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import java.lang.reflect.TypeVariable;
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import java.util.ArrayList;
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import java.util.List;
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import java.util.Map;
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import java.util.RandomAccess;
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import java.util.Set;
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import org.junit.Test;
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/**
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* Tests for {@link TypeToken}.
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*
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* @author Jesse Wilson
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*/
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public final class TypeTokenTest {
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// These fields are accessed using reflection by the tests below
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List<Integer> listOfInteger = null;
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List<Number> listOfNumber = null;
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List<String> listOfString = null;
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List<?> listOfUnknown = null;
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List<Set<String>> listOfSetOfString = null;
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List<Set<?>> listOfSetOfUnknown = null;
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@SuppressWarnings({"deprecation"})
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@Test
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public void testIsAssignableFromRawTypes() {
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assertThat(TypeToken.get(Object.class).isAssignableFrom(String.class)).isTrue();
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assertThat(TypeToken.get(String.class).isAssignableFrom(Object.class)).isFalse();
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assertThat(TypeToken.get(RandomAccess.class).isAssignableFrom(ArrayList.class)).isTrue();
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assertThat(TypeToken.get(ArrayList.class).isAssignableFrom(RandomAccess.class)).isFalse();
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}
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@SuppressWarnings({"deprecation"})
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@Test
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public void testIsAssignableFromWithTypeParameters() throws Exception {
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Type a = getClass().getDeclaredField("listOfInteger").getGenericType();
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Type b = getClass().getDeclaredField("listOfNumber").getGenericType();
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assertThat(TypeToken.get(a).isAssignableFrom(a)).isTrue();
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assertThat(TypeToken.get(b).isAssignableFrom(b)).isTrue();
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// listOfInteger = listOfNumber; // doesn't compile; must be false
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assertThat(TypeToken.get(a).isAssignableFrom(b)).isFalse();
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// listOfNumber = listOfInteger; // doesn't compile; must be false
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assertThat(TypeToken.get(b).isAssignableFrom(a)).isFalse();
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}
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@SuppressWarnings({"deprecation"})
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@Test
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public void testIsAssignableFromWithBasicWildcards() throws Exception {
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Type a = getClass().getDeclaredField("listOfString").getGenericType();
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Type b = getClass().getDeclaredField("listOfUnknown").getGenericType();
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assertThat(TypeToken.get(a).isAssignableFrom(a)).isTrue();
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assertThat(TypeToken.get(b).isAssignableFrom(b)).isTrue();
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// listOfString = listOfUnknown // doesn't compile; must be false
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assertThat(TypeToken.get(a).isAssignableFrom(b)).isFalse();
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listOfUnknown = listOfString; // compiles; must be true
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// The following assertion is too difficult to support reliably, so disabling
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// assertThat(TypeToken.get(b).isAssignableFrom(a)).isTrue();
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}
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@SuppressWarnings({"deprecation"})
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@Test
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public void testIsAssignableFromWithNestedWildcards() throws Exception {
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Type a = getClass().getDeclaredField("listOfSetOfString").getGenericType();
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Type b = getClass().getDeclaredField("listOfSetOfUnknown").getGenericType();
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assertThat(TypeToken.get(a).isAssignableFrom(a)).isTrue();
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assertThat(TypeToken.get(b).isAssignableFrom(b)).isTrue();
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// listOfSetOfString = listOfSetOfUnknown; // doesn't compile; must be false
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assertThat(TypeToken.get(a).isAssignableFrom(b)).isFalse();
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// listOfSetOfUnknown = listOfSetOfString; // doesn't compile; must be false
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assertThat(TypeToken.get(b).isAssignableFrom(a)).isFalse();
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}
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@Test
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public void testArrayFactory() {
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TypeToken<?> expectedStringArray = new TypeToken<String[]>() {};
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assertThat(TypeToken.getArray(String.class)).isEqualTo(expectedStringArray);
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TypeToken<?> expectedListOfStringArray = new TypeToken<List<String>[]>() {};
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Type listOfString = new TypeToken<List<String>>() {}.getType();
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assertThat(TypeToken.getArray(listOfString)).isEqualTo(expectedListOfStringArray);
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TypeToken<?> expectedIntArray = new TypeToken<int[]>() {};
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assertThat(TypeToken.getArray(int.class)).isEqualTo(expectedIntArray);
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assertThrows(NullPointerException.class, () -> TypeToken.getArray(null));
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}
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static class NestedGeneric<T> {}
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@Test
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public void testParameterizedFactory() {
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TypeToken<?> expectedListOfString = new TypeToken<List<String>>() {};
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assertThat(TypeToken.getParameterized(List.class, String.class))
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.isEqualTo(expectedListOfString);
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TypeToken<?> expectedMapOfStringToString = new TypeToken<Map<String, String>>() {};
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assertThat(TypeToken.getParameterized(Map.class, String.class, String.class))
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.isEqualTo(expectedMapOfStringToString);
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TypeToken<?> expectedListOfListOfListOfString = new TypeToken<List<List<List<String>>>>() {};
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Type listOfString = TypeToken.getParameterized(List.class, String.class).getType();
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Type listOfListOfString = TypeToken.getParameterized(List.class, listOfString).getType();
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assertThat(TypeToken.getParameterized(List.class, listOfListOfString))
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.isEqualTo(expectedListOfListOfListOfString);
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TypeToken<?> expectedWithExactArg = new TypeToken<GenericWithBound<Number>>() {};
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assertThat(TypeToken.getParameterized(GenericWithBound.class, Number.class))
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.isEqualTo(expectedWithExactArg);
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TypeToken<?> expectedWithSubclassArg = new TypeToken<GenericWithBound<Integer>>() {};
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assertThat(TypeToken.getParameterized(GenericWithBound.class, Integer.class))
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.isEqualTo(expectedWithSubclassArg);
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TypeToken<?> expectedSatisfyingTwoBounds =
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new TypeToken<GenericWithMultiBound<ClassSatisfyingBounds>>() {};
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assertThat(TypeToken.getParameterized(GenericWithMultiBound.class, ClassSatisfyingBounds.class))
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.isEqualTo(expectedSatisfyingTwoBounds);
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TypeToken<?> nestedTypeToken = TypeToken.getParameterized(NestedGeneric.class, Integer.class);
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ParameterizedType nestedParameterizedType = (ParameterizedType) nestedTypeToken.getType();
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// TODO: This seems to differ from how Java reflection behaves; when using
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// TypeToken<NestedGeneric<Integer>>, then NestedGeneric<Integer> does have an owner type
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assertThat(nestedParameterizedType.getOwnerType()).isNull();
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assertThat(nestedParameterizedType.getRawType()).isEqualTo(NestedGeneric.class);
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assertThat(nestedParameterizedType.getActualTypeArguments())
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.asList()
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.containsExactly(Integer.class);
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class LocalGenericClass<T> {}
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TypeToken<?> expectedLocalType = new TypeToken<LocalGenericClass<Integer>>() {};
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assertThat(TypeToken.getParameterized(LocalGenericClass.class, Integer.class))
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.isEqualTo(expectedLocalType);
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// For legacy reasons, if requesting parameterized type for non-generic class, create a
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// `TypeToken(Class)`
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assertThat(TypeToken.getParameterized(String.class)).isEqualTo(TypeToken.get(String.class));
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}
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@Test
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public void testParameterizedFactory_Invalid() {
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assertThrows(NullPointerException.class, () -> TypeToken.getParameterized(null, new Type[0]));
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assertThrows(
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NullPointerException.class,
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() -> TypeToken.getParameterized(List.class, new Type[] {null}));
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GenericArrayType arrayType = (GenericArrayType) TypeToken.getArray(String.class).getType();
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IllegalArgumentException e =
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assertThrows(
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IllegalArgumentException.class,
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() -> TypeToken.getParameterized(arrayType, new Type[0]));
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assertThat(e)
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.hasMessageThat()
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.isEqualTo("rawType must be of type Class, but was java.lang.String[]");
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e =
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assertThrows(
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IllegalArgumentException.class,
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() -> TypeToken.getParameterized(String.class, Number.class));
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assertThat(e)
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.hasMessageThat()
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.isEqualTo("java.lang.String requires 0 type arguments, but got 1");
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e =
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assertThrows(
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IllegalArgumentException.class,
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() -> TypeToken.getParameterized(List.class, new Type[0]));
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assertThat(e).hasMessageThat().isEqualTo("java.util.List requires 1 type arguments, but got 0");
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e =
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assertThrows(
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IllegalArgumentException.class,
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() -> TypeToken.getParameterized(List.class, String.class, String.class));
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assertThat(e).hasMessageThat().isEqualTo("java.util.List requires 1 type arguments, but got 2");
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// Primitive types must not be used as type argument
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e =
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assertThrows(
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IllegalArgumentException.class,
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() -> TypeToken.getParameterized(List.class, int.class));
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assertThat(e)
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.hasMessageThat()
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.isEqualTo(
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"Type argument int does not satisfy bounds for type variable E declared by "
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+ List.class);
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e =
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assertThrows(
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IllegalArgumentException.class,
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() -> TypeToken.getParameterized(GenericWithBound.class, String.class));
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assertThat(e)
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.hasMessageThat()
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.isEqualTo(
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"Type argument class java.lang.String does not satisfy bounds"
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+ " for type variable T declared by "
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+ GenericWithBound.class);
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e =
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assertThrows(
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IllegalArgumentException.class,
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() -> TypeToken.getParameterized(GenericWithBound.class, Object.class));
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assertThat(e)
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.hasMessageThat()
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.isEqualTo(
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"Type argument class java.lang.Object does not satisfy bounds"
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+ " for type variable T declared by "
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+ GenericWithBound.class);
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e =
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assertThrows(
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IllegalArgumentException.class,
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() -> TypeToken.getParameterized(GenericWithMultiBound.class, Number.class));
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assertThat(e)
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.hasMessageThat()
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.isEqualTo(
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"Type argument class java.lang.Number does not satisfy bounds"
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+ " for type variable T declared by "
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+ GenericWithMultiBound.class);
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e =
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assertThrows(
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IllegalArgumentException.class,
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() -> TypeToken.getParameterized(GenericWithMultiBound.class, CharSequence.class));
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assertThat(e)
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.hasMessageThat()
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.isEqualTo(
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"Type argument interface java.lang.CharSequence does not satisfy bounds"
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+ " for type variable T declared by "
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+ GenericWithMultiBound.class);
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e =
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assertThrows(
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IllegalArgumentException.class,
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() -> TypeToken.getParameterized(GenericWithMultiBound.class, Object.class));
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assertThat(e)
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.hasMessageThat()
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.isEqualTo(
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"Type argument class java.lang.Object does not satisfy bounds"
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+ " for type variable T declared by "
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+ GenericWithMultiBound.class);
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class Outer {
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class NonStaticInner<T> {}
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}
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e =
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assertThrows(
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IllegalArgumentException.class,
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() -> TypeToken.getParameterized(Outer.NonStaticInner.class, Object.class));
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assertThat(e)
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.hasMessageThat()
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.isEqualTo(
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"Raw type "
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+ Outer.NonStaticInner.class.getName()
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+ " is not supported because it requires specifying an owner type");
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}
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private static class CustomTypeToken extends TypeToken<String> {}
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@Test
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public void testTypeTokenNonAnonymousSubclass() {
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TypeToken<?> typeToken = new CustomTypeToken();
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assertThat(typeToken.getRawType()).isEqualTo(String.class);
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assertThat(typeToken.getType()).isEqualTo(String.class);
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}
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/**
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* User must only create direct subclasses of TypeToken, but not subclasses of subclasses (...) of
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* TypeToken.
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*/
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@Test
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public void testTypeTokenSubSubClass() {
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class SubTypeToken<T> extends TypeToken<String> {}
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class SubSubTypeToken1<T> extends SubTypeToken<T> {}
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class SubSubTypeToken2 extends SubTypeToken<Integer> {}
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IllegalStateException e =
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assertThrows(IllegalStateException.class, () -> new SubTypeToken<Integer>() {});
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assertThat(e).hasMessageThat().isEqualTo("Must only create direct subclasses of TypeToken");
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e = assertThrows(IllegalStateException.class, () -> new SubSubTypeToken1<Integer>());
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assertThat(e).hasMessageThat().isEqualTo("Must only create direct subclasses of TypeToken");
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e = assertThrows(IllegalStateException.class, () -> new SubSubTypeToken2());
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assertThat(e).hasMessageThat().isEqualTo("Must only create direct subclasses of TypeToken");
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}
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private static <M> void createTypeTokenTypeVariable() {
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new TypeToken<M>() {};
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}
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/**
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* TypeToken type argument must not contain a type variable because, due to type erasure, at
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* runtime only the bound of the type variable is available which is likely not what the user
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* wanted.
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*
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* <p>Note that type variables are allowed for the {@code TypeToken} factory methods calling
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* {@code TypeToken(Type)} because for them the return type is {@code TypeToken<?>} which does not
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* give a false sense of type-safety.
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*/
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@Test
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public void testTypeTokenTypeVariable() throws Exception {
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// Put the test code inside generic class to be able to access `T`
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class Enclosing<T> {
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class Inner {}
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void test() {
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String expectedMessage =
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"TypeToken type argument must not contain a type variable;"
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+ " captured type variable T declared by "
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+ Enclosing.class
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+ "\n"
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+ "See https://github.com/google/gson/blob/main/Troubleshooting.md#typetoken-type-variable";
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IllegalArgumentException e =
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assertThrows(IllegalArgumentException.class, () -> new TypeToken<T>() {});
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assertThat(e).hasMessageThat().isEqualTo(expectedMessage);
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e = assertThrows(IllegalArgumentException.class, () -> new TypeToken<List<List<T>>>() {});
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assertThat(e).hasMessageThat().isEqualTo(expectedMessage);
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e =
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assertThrows(
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IllegalArgumentException.class, () -> new TypeToken<List<? extends List<T>>>() {});
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assertThat(e).hasMessageThat().isEqualTo(expectedMessage);
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e =
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assertThrows(
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IllegalArgumentException.class, () -> new TypeToken<List<? super List<T>>>() {});
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assertThat(e).hasMessageThat().isEqualTo(expectedMessage);
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e = assertThrows(IllegalArgumentException.class, () -> new TypeToken<List<T>[]>() {});
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assertThat(e).hasMessageThat().isEqualTo(expectedMessage);
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e =
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assertThrows(
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IllegalArgumentException.class, () -> new TypeToken<Enclosing<T>.Inner>() {});
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assertThat(e).hasMessageThat().isEqualTo(expectedMessage);
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String systemProperty = "gson.allowCapturingTypeVariables";
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try {
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// Any value other than 'true' should be ignored
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System.setProperty(systemProperty, "some-value");
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e = assertThrows(IllegalArgumentException.class, () -> new TypeToken<T>() {});
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assertThat(e).hasMessageThat().isEqualTo(expectedMessage);
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} finally {
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System.clearProperty(systemProperty);
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}
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try {
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System.setProperty(systemProperty, "true");
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TypeToken<?> typeToken = new TypeToken<T>() {};
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assertThat(typeToken.getType()).isEqualTo(Enclosing.class.getTypeParameters()[0]);
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} finally {
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System.clearProperty(systemProperty);
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}
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}
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<M> void testMethodTypeVariable() throws Exception {
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Method testMethod = Enclosing.class.getDeclaredMethod("testMethodTypeVariable");
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IllegalArgumentException e =
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assertThrows(IllegalArgumentException.class, () -> new TypeToken<M>() {});
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assertThat(e)
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.hasMessageThat()
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.isAnyOf(
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"TypeToken type argument must not contain a type variable;"
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+ " captured type variable M declared by "
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+ testMethod
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+ "\n"
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+ "See https://github.com/google/gson/blob/main/Troubleshooting.md#typetoken-type-variable",
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// Note: When running this test in Eclipse IDE or with certain Java versions it
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// seems to capture `null` instead of the type variable, see
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// https://github.com/eclipse-jdt/eclipse.jdt.core/issues/975
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"TypeToken captured `null` as type argument; probably a compiler / runtime bug");
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}
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}
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new Enclosing<>().test();
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new Enclosing<>().testMethodTypeVariable();
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Method testMethod = TypeTokenTest.class.getDeclaredMethod("createTypeTokenTypeVariable");
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IllegalArgumentException e =
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assertThrows(IllegalArgumentException.class, () -> createTypeTokenTypeVariable());
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assertThat(e)
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.hasMessageThat()
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.isEqualTo(
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"TypeToken type argument must not contain a type variable;"
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+ " captured type variable M declared by "
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+ testMethod
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+ "\n"
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+ "See https://github.com/google/gson/blob/main/Troubleshooting.md#typetoken-type-variable");
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// Using type variable as argument for factory methods should be allowed; this is not a
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// type-safety problem because the user would have to perform unsafe casts
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TypeVariable<?> typeVar = Enclosing.class.getTypeParameters()[0];
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TypeToken<?> typeToken = TypeToken.get(typeVar);
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assertThat(typeToken.getType()).isEqualTo(typeVar);
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TypeToken<?> parameterizedTypeToken = TypeToken.getParameterized(List.class, typeVar);
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ParameterizedType parameterizedType = (ParameterizedType) parameterizedTypeToken.getType();
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assertThat(parameterizedType.getRawType()).isEqualTo(List.class);
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assertThat(parameterizedType.getActualTypeArguments()).asList().containsExactly(typeVar);
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}
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@SuppressWarnings("rawtypes")
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@Test
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public void testTypeTokenRaw() {
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IllegalStateException e = assertThrows(IllegalStateException.class, () -> new TypeToken() {});
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assertThat(e)
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.hasMessageThat()
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.isEqualTo(
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"TypeToken must be created with a type argument: new TypeToken<...>() {}; When using"
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+ " code shrinkers (ProGuard, R8, ...) make sure that generic signatures are"
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+ " preserved.\n"
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+ "See https://github.com/google/gson/blob/main/Troubleshooting.md#type-token-raw");
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}
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}
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// Have to declare these classes here as top-level classes because otherwise tests for
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// TypeToken.getParameterized fail due to owner type mismatch
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class GenericWithBound<T extends Number> {}
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class GenericWithMultiBound<T extends Number & CharSequence> {}
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@SuppressWarnings("serial")
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abstract class ClassSatisfyingBounds extends Number implements CharSequence {}
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