Drools testing with junit

Question

What is the best practice to test drools rules with junit?

Until now we used junit with dbunit to test rules. We had sample data that was put to hsqldb. We had couple of rule packages and by the end of the project it is very hard to make a good test input to test certain rules and not fire others.

So the exact question is that how can I limit tests in junit to one or more certain rule(s) for testing?

Answer 1

Do not attempt to limit rule execution to a single rule for a test. Unlike OO classes, single rules are not independent of other rules, so it does not make sense to test a rule in isolation in the same way that you would test a single class using a unit test. In other words, to test a single rule, test that it has the right effect in combination with the other rules.

Instead, run tests with a small amount of data on all of your rules, i.e. with a minimal number of facts in the rule session, and test the results and perhaps that a particular rule was fired. The result is not actually that much different from what you have in mind, because a minimal set of test data might only activate one or two rules.

As for the sample data, I prefer to use static data and define minimal test data for each test. There are various ways of doing this, but programmatically creating fact objects in Java might be good enough.