001 /* 002 * Created on Sep 8, 2010 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with 005 * the License. You may obtain a copy of the License at 006 * 007 * http://www.apache.org/licenses/LICENSE-2.0 008 * 009 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on 010 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the 011 * specific language governing permissions and limitations under the License. 012 * 013 * Copyright @2010-2011 the original author or authors. 014 */ 015 package org.fest.assertions.error; 016 017 import static org.fest.util.ToString.toStringOf; 018 019 import java.awt.image.BufferedImage; 020 021 import org.fest.assertions.description.Description; 022 import org.fest.util.*; 023 024 /** 025 * Formats the messages to be included in assertion errors. 026 * 027 * @author Alex Ruiz 028 */ 029 public class MessageFormatter { 030 031 private static final MessageFormatter INSTANCE = new MessageFormatter(); 032 033 /** 034 * Returns the singleton instance of this class. 035 * @return the singleton instance of this class. 036 */ 037 public static MessageFormatter instance() { 038 return INSTANCE; 039 } 040 041 @VisibleForTesting DescriptionFormatter descriptionFormatter = DescriptionFormatter.instance(); 042 043 @VisibleForTesting MessageFormatter() {} 044 045 /** 046 * Interprets a printf-style format {@code String} for failed assertion messages. It is similar to 047 * <code>{@link String#format(String, Object...)}</code>, except for: 048 * <ol> 049 * <li>the value of the given <code>{@link Description}</code> is used as the first argument referenced in the format 050 * string</li> 051 * <li>each of the arguments in the given array is converted to a {@code String} by invoking 052 * <code>{@link ToString#toStringOf(Object)}</code>. 053 * </ol> 054 * @param d the description of the failed assertion, may be {@code null}. 055 * @param format the format string. 056 * @param args arguments referenced by the format specifiers in the format string. 057 * @throws NullPointerException if the format string is {@code null}. 058 * @return A formatted {@code String}. 059 */ 060 public String format(Description d, String format, Object... args) { 061 if (format == null) throw new NullPointerException("The format string should not be null"); 062 if (args == null) throw new NullPointerException("The array of arguments should not be null"); 063 return descriptionFormatter.format(d) + String.format(format, format(args)); 064 } 065 066 private Object[] format(Object[] args) { 067 int argCount = args.length; 068 String[] formatted = new String[argCount]; 069 for (int i = 0; i < argCount; i++) 070 formatted[i] = asText(args[i]); 071 return formatted; 072 } 073 074 private String asText(Object o) { 075 if (o instanceof BufferedImage) return "image"; 076 if (o instanceof ComparatorBasedComparisonStrategy) return " according to " + o + " comparator"; 077 if (o instanceof StandardComparisonStrategy) return ""; 078 return toStringOf(o); 079 } 080 }