BDDCatchException.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.assertj.core.api.AbstractThrowableAssert;

import com.googlecode.catchexception.CatchException;

/**
 * Supports <a
 * href="http://en.wikipedia.org/wiki/Behavior_Driven_Development">BDD</a>-like
 * approach to catch and verify exceptions (<i>given/when/then</i>).
 * <p/>
 * EXAMPLE:
 * <code><pre class="prettyprint lang-java">import static org.assertj.core.api.BDDAssertions.then;
 * <p/>
 * // given an empty list
 * List myList = new ArrayList();
 * <p/>
 * // when we try to get the first element of the list
 * when(myList).get(1);
 * <p/>
 * // then we expect an IndexOutOfBoundsException
 * then(caughtException())
 * .isInstanceOf(IndexOutOfBoundsException.class)
 * .hasMessage("Index: 1, Size: 0")
 * .hasNoCause();
 * <p/>
 * // then we expect an IndexOutOfBoundsException (alternatively)
 * thenThrown(IndexOutOfBoundsException.class);
 * </pre></code>
 * <p/>
 * import static org.assertj.core.api.BDDAssertions.then;
 * <p/>
 * // given an empty list
 * List myList = new ArrayList();
 * <p/>
 * // when we try to get the first element of the list
 * when(myList).get(1);
 * <p/>
 * // then we expect an IndexOutOfBoundsException
 * then(caughtException())
 * .isInstanceOf(IndexOutOfBoundsException.class)
 * .hasMessage("Index: 1, Size: 0")
 * .hasNoCause();
 * <p/>
 * // then we expect an IndexOutOfBoundsException (alternatively)
 * thenThrown(IndexOutOfBoundsException.class);
 * }
 * </pre>
 *
 * @author rwoo
 * @author mariuszs
 * @since 1.3.0
 */
public class BDDCatchException {

    /**
     * @param <T> The type of the given <code>obj</code>.
     * @param obj The instance that shall be proxied. Must not be
     *            <code>null</code>.
     * @return Returns a proxy for the given object. The proxy catches
     * exceptions of the given type when a method on the proxy is
     * called.
     * @see com.googlecode.catchexception.CatchException#catchException(Object)
     */
    public static <T> T when(T obj) {
        return CatchException.catchException(obj);
    }

    /**
     * Throws an assertion if no exception is thrown or if an exception of an
     * unexpected type is thrown.
     * <p/>
     * EXAMPLE:
     * <code><pre class="prettyprint lang-java">// given a list with nine members
     * List myList = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9);
     * <p/>
     * // when we try to get the 500th member of the fellowship
     * when(myList).get(500);
     * <p/>
     * // then we expect an IndexOutOfBoundsException
     * thenThrown(IndexOutOfBoundsException.class);
     * </pre></code>
     * <p/>
     * // given a list with nine members
     * List myList = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9);
     * <p/>
     * // when we try to get the 500th member of the fellowship
     * when(myList).get(500);
     * <p/>
     * // then we expect an IndexOutOfBoundsException
     * thenThrown(IndexOutOfBoundsException.class);
     * }
     * </pre>
     *
     * @param actualExceptionClazz the expected type of the caught exception.
     */
    @SuppressWarnings("rawtypes")
    public static void thenThrown(Class actualExceptionClazz) {
        CatchExceptionUtils.thenThrown(actualExceptionClazz);
    }

    /**
     * Enables <a
     * href="https://github.com/joel-costigliola/assertj-core">AssertJ</a>
     * assertions about the caught exception.
     * <p/>
     * EXAMPLE:
     * <code><pre class="prettyprint lang-java">// given an empty list
     * List myList = new ArrayList();
     * <p/>
     * // when we try to get first element of the list
     * when(myList).get(1);
     * <p/>
     * // then we expect an IndexOutOfBoundsException
     * then(caughtException())
     * .isInstanceOf(IndexOutOfBoundsException.class)
     * .hasMessage("Index: 1, Size: 0")
     * .hasMessageStartingWith("Index: 1")
     * .hasMessageEndingWith("Size: 0")
     * .hasMessageContaining("Size")
     * .hasNoCause();
     * </pre></code>
     *
     * @param actualException the value to be the target of the assertions methods.
     * @return Returns the created assertion object.
     * @deprecated Use {@link BDDAssertions#then(Exception)} instead
     */
    @Deprecated
    public static AbstractThrowableAssert<?, ? extends Exception> then(Exception actualException) {
        // delegate to AssertJ assertions
        return new CatchExceptionAssert(actualException);
    }

    /**
     * Returns the exception caught during the last call on the proxied object
     * in the current thread.
     *
     * @return Returns the exception caught during the last call on the proxied object in the current thread - if the
     * call was made through a proxy that has been created via {@link #when(Object)} . Returns null the proxy has not
     * caught an exception. Returns null if the caught exception belongs to a class that is no longer {@link
     * ClassLoader loaded}.
     */
    public static Exception caughtException() {
        return CatchException.caughtException();
    }

}