Groovy closure to implement matcher in Fest

Question

I am trying to create a closure matcher for Fest with Groovy (2.1.6) like this:

def matcherLabel = [ isMatching: { JLabel label -> /* do something */ } ] as GenericTypeMatcher<JLabel>

GenericTypeMatcher is an abstract class with one method only to implement (isMatching (T t))

but I get this error:

org.codehaus.groovy.runtime.typehandling.GroovyCastException: Error casting map to org.fest.swing.core.GenericTypeMatcher, Reason: null
at org.codehaus.groovy.runtime.DefaultGroovyMethods.asType(DefaultGroovyMethods.java:7562)

Is it possible what I am trying to do?

Answer 1

Your problem is that the GenericTypeMatcher class doesn't have a default, zero-parameter constructor. Cast the map to an interface like ComponentMatcher instead. If you can't use an interface, another alternative is to subclass GenericTypeMatcher and provide a zero-parameter constructor.