New Event Filtering: Add rekt test to verify that empty filters does not override filter

[Cali0707]

Problem
With the new subscriptionsapi filters moving to enabled by default, users can now use both the filters field on a trigger as well as the filter field on a trigger. The order of priority of these fields when filtering an event is:

1. If there are filters in the filters field and the feature is enabled, use the filters field.
2. If there are no filters in the filters field and the feature is enabled, fallback to the filter field.
3. If there is a filter in the filter field apply it
4. If the above fails, pass the event (there is no filtering to be done)

Exit Criteria
A test in the new trigger filters rekt tests which:

1. Create a trigger
2. Sets a filter, but nothing in the filters field
3. Sends events to the broker which match the filter and verifies that they are delivered
4. Sends events to the broker which do not match the filter and verifies that they are not delivered

Time Estimate (optional):
How many developer-days do you think this may take to resolve? 1

Additional context (optional)
Add any other context about the feature request here.

• [Experimental] Enhanced Trigger filters via adopting CloudEvent Subscriptions API #5204
• Fixed logic to choose whether to use filter or filters for a trigger #7286

[Cali0707]

/area test-and-release
/help

[knative-prow]

@Cali0707:
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In response to this:

/area test-and-release
/help

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[rahulii]

/assign

[Cali0707]

Hey @rahulii any updates on this? Is there anything I can help you with here? If you're still working on this issue please let me know, otherwise I will unassign it from you this coming Friday so others can work on it.

[Cali0707]

@rahulii I'm going to unassign this issue from you now so others can work on it. Feel free to re-assign yourself if you want to work on it again!

/unassign @rahulii

[pawarpranav83]

Hi! Currently working on this test, will make a PR soon.

/assign

[pawarpranav83]

@Cali0707
Approach - Add filter parameter (eventingv1.TriggerFilter) to createNewFiltersFeature and create a feature function in rekt/features/new_trigger_filters/feature.go for filter attributes and filters would be empty and append it to the featureSet.
Should I make these changes?

[Cali0707]

@Cali0707 Approach - Add filter parameter (eventingv1.TriggerFilter) to createNewFiltersFeature and create a feature function in rekt/features/new_trigger_filters/feature.go for filter attributes and filters would be empty and append it to the featureSet. Should I make these changes?

@pradnyavmw sure that sounds like a reasonable approach, go for it! Would you also be able to add one more feature in rekt/features/new_trigger_filters/feature.go to verify that when both the filter and filters fields are set, filters overrides the filter field?