001/*
002 * Copyright 2015 SirWellington Tech.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package tech.sirwellington.alchemy.test.mockito;
018
019import org.mockito.invocation.InvocationOnMock;
020import org.mockito.stubbing.Answer;
021import tech.sirwellington.alchemy.annotations.access.NonInstantiable;
022
023import static tech.sirwellington.alchemy.test.Checks.Internal.checkThat;
024
025/**
026 * This class contains a variety of useful answers for use in combination with Mockito.
027 *
028 * @author SirWellington
029 */
030@NonInstantiable
031public final class MoreAnswers
032{
033
034    MoreAnswers() throws IllegalAccessException
035    {
036        throw new IllegalAccessException("cannot instantiate class");
037    }
038
039
040    /**
041     * For example:
042     * <p>
043     * <pre>
044     *
045     * {@code
046     * when(object.call("firstArg", 3)).then(returnFirst());
047     * }
048     * Will return the {@code "firstArg"} string when it is called.
049     * </pre>
050     *
051     * @param <T>
052     * @return
053     * @see #returnArgumentAtIndex(int)
054     */
055    public static <T> Answer<T> returnFirst()
056    {
057        return returnArgumentAtIndex(0);
058    }
059
060    /**
061     * An answer that returns one of the parameters as the return value.
062     * <p>
063     * Example:
064     * <pre>
065     * when(someMock.call(anyString(), anyString()).then(returnArgumentAtIndex(1));
066     *
067     * String result = someMock.call("arg1", "arg2");
068     * assertThat(result, is("arg2"));
069     * </pre>
070     *
071     * @param <T>
072     * @param index zero-based index which determines which parameter to return as an answer.
073     * @return
074     * @see #returnFirst()
075     */
076    public static <T> Answer<T> returnArgumentAtIndex(final int index)
077    {
078        checkThat(index >= 0, "Index is out of bounds.");
079
080        return new Answer<T>()
081        {
082            @Override
083            public T answer(InvocationOnMock invocation) throws Throwable
084            {
085                if (index >= invocation.getArguments().length)
086                {
087                    throw new IllegalArgumentException("Received an index of " + index + " but only " + invocation.getArguments().length + " arguments");
088                }
089
090                return (T) invocation.getArguments()[index];
091            }
092        };
093    }
094}