/**
* 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>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] = asText(args[i]);
}
return formatted;
}
private String asText(Object o) {
if (o instanceof ComparatorBasedComparisonStrategy) {
return " according to " + o + " comparator";
}
if (o instanceof StandardComparisonStrategy) {
return "";
}
return toStringOf(o);
}
}
/**
* 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>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));
}
