CatchExceptionHamcrestMatchers.java

/**
 * Copyright (C) 2011 rwoo@gmx.de
 *
 * 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.googlecode.catchexception.apis;

import org.hamcrest.Matcher;
import org.junit.matchers.JUnitMatchers;

import com.googlecode.catchexception.apis.internal.hamcrest.ExceptionMessageMatcher;
import com.googlecode.catchexception.apis.internal.hamcrest.ExceptionNoCauseMatcher;

/**
 * Provides some Hamcrest {@link Matcher matchers} to match some
 * {@link Exception exception} properties.
 * <p>
 * EXAMPLE:
 * <code><pre class="prettyprint lang-java">// given an empty list
List myList = new ArrayList();

// when we try to get the first element of the list
catchException(myList).get(1);

// then we expect an IndexOutOfBoundsException with message "Index: 1, Size: 0" 
assertThat(caughtException(),
  allOf(
    is(IndexOutOfBoundsException.class), 
    hasMessage("Index: 1, Size: 0"),
    hasNoCause()
  )
);</pre></code>
 * <p>
 * To combine the standard Hamcrest matchers, your custom matchers, these
 * matchers, and other matcher collections (as {@link JUnitMatchers}) in a
 * single class follow the instructions outlined in <a
 * href="http://code.google.com/p/hamcrest/wiki/Tutorial#Sugar_generation">Sugar
 * generation</a>.
 * <p>
 * Hint: This class might use <a
 * href="http://code.google.com/p/hamsandwich">hamsandwich</a> in the future but
 * as long as hamsandwich is not in any public maven repository, this class will
 * not use hamsandwich.
 * 
 * @author rwoo
 */
public class CatchExceptionHamcrestMatchers {

    /**
     * EXAMPLE:
     * <code><pre class="prettyprint lang-java">assertThat(caughtException(), hasMessage("Index: 9, Size: 9"));</pre></code>
     * 
     * @param <T>
     *            the exception subclass
     * @param expectedMessage
     *            the expected exception message
     * @return Returns a matcher that matches an exception if it has the given
     *         message.
     */
    public static <T extends Exception> org.hamcrest.Matcher<T> hasMessage(
            String expectedMessage) {
        return new ExceptionMessageMatcher<T>(expectedMessage);
    }

    /**
     * EXAMPLES:
     * <code><pre class="prettyprint lang-java">assertThat(caughtException(), hasMessageThat(is("Index: 9, Size: 9")));
assertThat(caughtException(), hasMessageThat(containsString("Index: 9"))); // using JUnitMatchers
assertThat(caughtException(), hasMessageThat(containsPattern("Index: \\d+"))); // using Mockito's Find</pre></code>
     * 
     * @param <T>
     *            the exception subclass
     * @param stringMatcher
     *            a string matcher
     * @return Returns a matcher that matches an exception if the given string
     *         matcher matches the exception message.
     */
    public static <T extends Exception> org.hamcrest.Matcher<T> hasMessageThat(
            Matcher<String> stringMatcher) {
        return new ExceptionMessageMatcher<T>(stringMatcher);
    }

    /**
     * EXAMPLE:
     * <code><pre class="prettyprint lang-java">assertThat(caughtException(), hasNoCause());</pre></code>
     * 
     * @param <T>
     *            the exception subclass
     * @return Returns a matcher that matches the exception if it does not have
     *         a {@link Throwable#getCause() cause}.
     */
    public static <T extends Exception> org.hamcrest.Matcher<T> hasNoCause() {
        return new ExceptionNoCauseMatcher<T>();
    }

}