A test that threw total nonsense malformed XML at it passed without any problems.
The next test was to pass in XML where one the attributes should have been a number, but the test passed a String. The test expected an Exception to be thrown, but there wasn't one and it failed. Surprisingly, Digester silently ignored the fact that the attribute could not be parsed into a long and simply left the attribute on the target class as zero.
Googling revealed two issues.
The first was that the default ErrorHandler for Digester swallows Exceptions. Bad stuff, but can be remedied by creating your own ErrorHandler:
ErrorHandler errorHandler = new ErrorHandler() {
public void warning (SAXParseException e) throws SAXParseException { throw e; }
public void error (SAXParseException e) throws SAXParseException { throw e; }
public void fatalError(SAXParseException e) throws SAXParseException { throw e; }
};
Digester digester = new Digester();
digester.setErrorHandler(errorHandler);
This did not fix the test!
Further digging found that Digester depends on Apache Commons BeanUtils. In particular, it uses ConvertUtils to perform type conversions. The default converter is the culprit which silently does nothing if a conversion cannot be performed.
OK, so just right our own converter, right? Maybe.
You can right your own converter and you register it with ConvertUtils. But, the method signature for register is:
public static void register(Converter converter, Class clazz)
static!
This means that your custom converter will be used by all the Digester instances in your application. What's wrong with that? Well, in my case, this is a legacy application with test coverage around 1%. There may be code that 'depends' on the brokenness of the default converter behavior in Digester. Also, Digester is used by some other open source frameworks that may be in the project.
In the end, I decided not to use Digester and instead used dom4j which also allowed for a quick solution, but did the right thing and allowed me to control behavior on an instance by instance basis rather than using statics.
