Haven't looked deeper at the different test.<> functions, but was wondering what this is supposed to do here? You're setting extensions on the input event based on got and then asserting. Is this correctly exercising and asserting the changes here?

There is another way we can remove the KAFKA_OFFSET , KAFKA_PARTITION, and KAFKA_TOPIC from got. Is this way better?

I'm curious, how do we remove extension attributes from a CE? I didn't see that option in here: https://github.com/cloudevents/sdk-go/blob/main/v2/event/event_writer.go

I'm ok with copying things from got into eventIn so that the Assert works (or removing them from got if that's possible), but it seems to me that there should be a check of the values in got to make sure they're not blank - even if we need to do those manually instead via a compare with eventIn.

@duglin Thanks for your advice! I have added the empty check for the event extensions.

can we check their values? Should they match the constants defined above?

Sure! But we can only verify the topic defined above. And the partition/offset isn't defined here.

Suggesting the following changes for more clarity of the test (also for the other integration test):

func TestSendEvent(t *testing.T) {
	test.EachEvent(t, test.Events(), func(t *testing.T, eventIn event.Event) {
		eventIn = test.ConvertEventExtensionsToString(t, eventIn)
		clienttest.SendReceive(t, func() interface{} {
			return protocolFactory(t)
		}, eventIn, func(eventOut event.Event) {
			eventOut = test.ConvertEventExtensionsToString(t, eventOut)

			require.Equal(t, TopicName, eventOut.Extensions()[KAFKA_TOPIC])
			require.NotNil(t, eventOut.Extensions()[KAFKA_PARTITION])
			require.NotNil(t, eventOut.Extensions()[KAFKA_OFFSET])

			test.AllOf(
				test.HasExactlyAttributesEqualTo(eventIn.Context),
				test.HasData(eventIn.Data()),
			)
		})
	})
}

Renamed the variable names for more clarity and dropped extension comparison since we're not setting specific extensions here and have require... to assert on the specific extensions we want. Ideally we'd have a custom test.EventMatcher to assert on extensions but skip specific ones which get added at a later stage. I'll create tracking issue.

Done!
Thank @embano1!