// special mock context
// 1. will return no service for the null Filter ("null")
// 2. will return ref2 for filter serv2Filter
// the same goes with getService
ctx = new MockBundleContext() {
public ServiceReference[] getServiceReferences(String clazz, String filter) throws InvalidSyntaxException {
if (serv2Filter.equals(filter))
return new ServiceReference[] { ref2 };
else if (nullFilter.equals(filter)) {