Changes to Pubsub Test for ExactlyOnce (#269)

* fix: bad feature check for ExactlyOnce

* fix: skip TestMessageCtx when ExactlyOnceDelivery is being tested

* when testing with NATS jetstream the broker will not allow message
  republication with the same message ID

* fix: skip TestContinueAfterSubscribeClose if not persistent

pubsub/tests/test_pubsub.go

@@ -584,6 +584,10 @@ func TestContinueAfterSubscribeClose(
 	createPubSub PubSubConstructor,
 ) {
 	if !tCtx.Features.Persistent {
+		t.Skip("Non-Persistent is not supported yet")
+	}
+
+	if tCtx.Features.ExactlyOnceDelivery {
 		t.Skip("ExactlyOnceDelivery test is not supported yet")
 	}
 
@@ -886,6 +890,13 @@ func TestMessageCtx(
 	tCtx TestContext,
 	pubSubConstructor PubSubConstructor,
 ) {
+	if tCtx.Features.ExactlyOnceDelivery {
+		// with ExactlyOnce delivery (at least as implemented by NATS jetstream)
+		// the second message will never be received because the broker deduplicates
+		// by message ID.
+		t.Skip("ExactlyOnceDelivery test is not supported yet")
+	}
+
 	pub, sub := pubSubConstructor(t)
 	defer closePubSub(t, pub, sub)