ThrowableAssert.java

/*
 * Created on Dec 23, 2007
 * 
 * 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.
 * 
 * Copyright @2007-2013 the original author or authors.
 */
package org.fest.assertions;

import org.fest.util.VisibleForTesting;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;

import static org.fest.assertions.Fail.failIfNotEqual;
import static org.fest.assertions.Formatting.format;
import static org.fest.util.Preconditions.checkNotNull;

/**
 * Assertions for {@code Throwable}.
 * <p/>
 * To create a new instance of this class invoke {@link Assertions#assertThat(Throwable)}.
 *
 * @author David DIDIER
 * @author Alex Ruiz
 */
public class ThrowableAssert extends GenericAssert<ThrowableAssert, Throwable> {
  // TODO remove dependency on ObjectAssert.
  @VisibleForTesting
  final ObjectAssert objectAssert;

  /**
   * Creates a new {@link ThrowableAssert}.
   *
   * @param actual the target to verify.
   */
  protected ThrowableAssert(@Nullable Throwable actual) {
    super(ThrowableAssert.class, actual);
    objectAssert = new ObjectAssert(actual);
  }

  /**
   * Verifies that the actual {@code Throwable} is an instance of the given type.
   *
   * @param type the type to check the actual {@code Throwable} against.
   * @return this assertion object.
   * @throws AssertionError       if the actual {@code Throwable} is {@code null}.
   * @throws AssertionError       if the actual {@code Throwable} is not an instance of the given type.
   * @throws NullPointerException if the given type is {@code null}.
   */
  public @Nonnull ThrowableAssert isInstanceOf(@Nonnull Class<? extends Throwable> type) {
    objectAssert.isInstanceOf(type);
    return this;
  }

  /**
   * Verifies that the actual {@code Throwable} is an instance of the given type. In order for the assertion to pass,
   * the type of the actual {@code Throwable} has to be exactly the same as the given type.
   *
   * @param type the type to check the actual {@code Throwable} against.
   * @return this assertion object.
   * @throws AssertionError       if the actual {@code Throwable} is {@code null}.
   * @throws AssertionError       if the actual {@code Throwable} is not an instance of the given type.
   * @throws NullPointerException if the given type is {@code null}.
   */
  public @Nonnull ThrowableAssert isExactlyInstanceOf(@Nonnull Class<?> type) {
    isNotNull();
    checkNotNull(type);
    Class<?> current = actual.getClass();
    if (type.equals(current)) {
      return this;
    }
    failIfCustomMessageIsSet();
    throw failure(format("expected exactly the same type:<%s> but was:<%s>", type, current));
  }

  /**
   * Verifies that the message of the actual {@code Throwable} is equal to the given one.
   *
   * @param message the expected message.
   * @return this assertion error.
   * @throws AssertionError if the actual {@code Throwable} is {@code null}.
   * @throws AssertionError if the message of the actual {@code Throwable} is not equal to the given one.
   */
  public @Nonnull ThrowableAssert hasMessage(@Nullable String message) {
    isNotNull();
    failIfNotEqual(customErrorMessage(), rawDescription(), actual.getMessage(), message);
    return this;
  }

  /**
   * Verifies that the actual {@code Throwable} does not have a cause.
   *
   * @return this assertion object.
   * @throws AssertionError if the actual {@code Throwable} is {@code null}.
   * @throws AssertionError if the actual {@code Throwable} has a cause.
   */
  public @Nonnull ThrowableAssert hasNoCause() {
    isNotNull();
    Throwable actualCause = actual.getCause();
    if (actualCause == null) {
      return this;
    }
    failIfCustomMessageIsSet();
    throw failure(format("expected exception without cause, but cause was:<%s>", actualCause.getClass()));
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public @Nonnull ThrowableAssert as(@Nullable String description) {
    objectAssert.as(description);
    return super.as(description);
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public @Nonnull ThrowableAssert describedAs(@Nullable String description) {
    return as(description);
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public @Nonnull ThrowableAssert as(@Nullable Description description) {
    objectAssert.as(description);
    return super.as(description);
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public @Nonnull ThrowableAssert describedAs(@Nullable Description description) {
    return as(description);
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public @Nonnull ThrowableAssert overridingErrorMessage(@Nullable String message) {
    objectAssert.overridingErrorMessage(message);
    return super.overridingErrorMessage(message);
  }
}