You should not have try/catch in your tests, instead you can use the provision for failures, here is an example:

```
    "test expandInstanceForEnv1": function () {
        var instance = {
           type: 'test_mojit_1',
           config: {testKey4: 'other'}
        };
        A.throwsError('<expected error message goes here.....>', function () {
            // this function gets executed immediately...
            this.store.expandInstanceForEnv("client", instance, {}, function(err, base) {});
        });
    }
```

more details here:

http://yuilibrary.com/yui/docs/api/classes/Test.Assert.html#method_throwsError