UtilTest.java

/*
 * Copyright 2013 Netflix, 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 feign;

import org.junit.Test;

import java.io.Reader;
import java.lang.reflect.Type;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import feign.codec.Decoder;

import static feign.Util.resolveLastTypeParameter;
import static org.assertj.core.api.Assertions.assertThat;
import static org.junit.Assert.assertEquals;

public class UtilTest {

  @Test
  public void emptyValueOf() throws Exception {
    assertEquals(false, Util.emptyValueOf(boolean.class));
    assertEquals(false, Util.emptyValueOf(Boolean.class));
    assertThat((byte[]) Util.emptyValueOf(byte[].class)).isEmpty();
    assertEquals(Collections.emptyList(), Util.emptyValueOf(Collection.class));
    assertThat((Iterator<?>) Util.emptyValueOf(Iterator.class)).isEmpty();
    assertEquals(Collections.emptyList(), Util.emptyValueOf(List.class));
    assertEquals(Collections.emptyMap(), Util.emptyValueOf(Map.class));
    assertEquals(Collections.emptySet(), Util.emptyValueOf(Set.class));
  }

  /** In other words, {@code List<String>} is as empty as {@code List<?>}. */
  @Test
  public void emptyValueOf_considersRawType() throws Exception {
    Type listStringType = LastTypeParameter.class.getDeclaredField("LIST_STRING").getGenericType();
    assertThat((List<?>) Util.emptyValueOf(listStringType)).isEmpty();
  }

  /** Ex. your {@code Foo} object would be null, but so would things like Number. */
  @Test
  public void emptyValueOf_nullForUndefined() throws Exception {
    assertThat(Util.emptyValueOf(Number.class)).isNull();
    assertThat(Util.emptyValueOf(Parameterized.class)).isNull();
  }

  @Test
  public void resolveLastTypeParameterWhenNotSubtype() throws Exception {
    Type context =
        LastTypeParameter.class.getDeclaredField("PARAMETERIZED_LIST_STRING").getGenericType();
    Type listStringType = LastTypeParameter.class.getDeclaredField("LIST_STRING").getGenericType();
    Type last = resolveLastTypeParameter(context, Parameterized.class);
    assertEquals(listStringType, last);
  }

  @Test
  public void lastTypeFromInstance() throws Exception {
    Parameterized<?> instance = new ParameterizedSubtype();
    Type last = resolveLastTypeParameter(instance.getClass(), Parameterized.class);
    assertEquals(String.class, last);
  }

  @Test
  public void lastTypeFromAnonymous() throws Exception {
    Parameterized<?> instance = new Parameterized<Reader>() {
    };
    Type last = resolveLastTypeParameter(instance.getClass(), Parameterized.class);
    assertEquals(Reader.class, last);
  }

  @Test
  public void resolveLastTypeParameterWhenWildcard() throws Exception {
    Type context =
        LastTypeParameter.class.getDeclaredField("PARAMETERIZED_WILDCARD_LIST_STRING")
            .getGenericType();
    Type listStringType = LastTypeParameter.class.getDeclaredField("LIST_STRING").getGenericType();
    Type last = resolveLastTypeParameter(context, Parameterized.class);
    assertEquals(listStringType, last);
  }

  @Test
  public void resolveLastTypeParameterWhenParameterizedSubtype() throws Exception {
    Type context =
        LastTypeParameter.class.getDeclaredField("PARAMETERIZED_DECODER_LIST_STRING")
            .getGenericType();
    Type listStringType = LastTypeParameter.class.getDeclaredField("LIST_STRING").getGenericType();
    Type last = resolveLastTypeParameter(context, ParameterizedDecoder.class);
    assertEquals(listStringType, last);
  }

  @Test
  public void unboundWildcardIsObject() throws Exception {
    Type context =
        LastTypeParameter.class.getDeclaredField("PARAMETERIZED_DECODER_UNBOUND").getGenericType();
    Type last = resolveLastTypeParameter(context, ParameterizedDecoder.class);
    assertEquals(Object.class, last);
  }

  interface LastTypeParameter {
    final List<String> LIST_STRING = null;
    final Parameterized<List<String>> PARAMETERIZED_LIST_STRING = null;
    final Parameterized<? extends List<String>> PARAMETERIZED_WILDCARD_LIST_STRING = null;
    final ParameterizedDecoder<List<String>> PARAMETERIZED_DECODER_LIST_STRING = null;
    final ParameterizedDecoder<?> PARAMETERIZED_DECODER_UNBOUND = null;
  }

  interface ParameterizedDecoder<T extends List<String>> extends Decoder {

  }

  interface Parameterized<T> {

  }

  static class ParameterizedSubtype implements Parameterized<String> {

  }
}