@Test
    public void transient_errors_expected_during_normal_feed_are_not_counted_as_errors_that_may_trigger_random_send() {
        setUpSingleNodeFixturesWithInitializedPolicy();
        var checker = policyFactory.getLastParameters().instabilityChecker;
        assertEquals(0, checker.recordedFailures); // WrongDistributionReply not counted as regular error
        {
            frame.setMessage(createMessage("id:ns:testdoc:n=2:foo"));
            RoutingNode target = select();
            replyError(target, new com.yahoo.messagebus.Error(DocumentProtocol.ERROR_BUSY, "Get busy livin' or get busy resendin'"));
        }
        assertEquals(0, checker.recordedFailures); // BUSY not counted as error
        {
            frame.setMessage(createMessage("id:ns:testdoc:n=3:foo"));
            RoutingNode target = select();
            replyError(target, new com.yahoo.messagebus.Error(DocumentProtocol.ERROR_TEST_AND_SET_CONDITION_FAILED, "oh no"));
        }
        assertEquals(0, checker.recordedFailures); // TaS failures not counted as error
    }
With two failures, one marked down, hopefully the one not marked down doesn't lead us to use the one marked down.
documentapi/src/test/java/com/yahoo/documentapi/messagebus/protocol/test/storagepolicy/ContentPolicyTest.java