content: /*
   * Created on Sep 8, 2010
   *
   * 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 @2010-2012 the original author or authors.
   */
  package org.fest.assertions.error;
  
  import static org.fest.util.Preconditions.checkNotNull;
  import static org.fest.util.ToString.toStringOf;
  
  import org.fest.assertions.description.Description;
  import org.fest.util.ToString;
  import org.fest.util.VisibleForTesting;
  
  /**
   * Formats the messages to be included in assertion errors.
   *
   * @author Alex Ruiz
   */
  public class MessageFormatter {
    private static final MessageFormatter INSTANCE = new MessageFormatter();
  
    public static MessageFormatter instance() {
      return INSTANCE;
    }
  
    @VisibleForTesting
    DescriptionFormatter descriptionFormatter = DescriptionFormatter.instance();
  
    @VisibleForTesting
    MessageFormatter() {}
  
    /**
     * Interprets a printf-style format {@code String} for failed assertion messages. It is similar to
     * <code>{@link String#format(String, Object...)}</code>, except for:
     * <ol>
     * <li>the value of the given <code>{@link Description}</code> is used as the first argument referenced in the format
     * string</li>
     * <li>each of the arguments in the given array is converted to a {@code String} by invoking
     * <code>{@link ToString#toStringOf(Object)}</code>.
     * </ol>
     *
     * @param d the description of the failed assertion, may be {@code null}.
     * @param format the format string.
     * @param args arguments referenced by the format specifiers in the format string.
     * @throws NullPointerException if the format string is {@code null}.
     * @return A formatted {@code String}.
     */
    public String format(Description d, String format, Object... args) {
      checkNotNull(format);
      checkNotNull(args);
      return descriptionFormatter.format(d) + String.format(format, format(args));
    }
  
    private Object[] format(Object[] args) {
      int argCount = args.length;
      String[] formatted = new String[argCount];
      for (int i = 0; i < argCount; i++) {
        formatted[i] = toStringOf(args[i]);
      }
      return formatted;
    }
  }
  