The culprit being PubSubTest181 where it subscribes after the publish rather than before. Increasing the sleep before the publish from 2ms -> 10ms should alleviate this though will now extend the total tests running time by 16s (when doing so for the other similar test also).
The following test occasionally becomes unsynchronized between the subscriptions and publishes as shown in the redis MONITOR output:
1446773145.007342 [0 127.0.0.1:42957] "AUTH" "foobared"
1446773145.007563 [0 127.0.0.1:42957] "SUBSCRIBE" "PubSubTest179"
1446773145.009523 [0 127.0.0.1:42779] "PUBLISH" "PubSubTest179" "3"
1446773145.009705 [0 127.0.0.1:42779] "PUBLISH" "PubSubTest179" "10000"
1446773145.010064 [0 127.0.0.1:42958] "AUTH" "foobared"
1446773145.010255 [0 127.0.0.1:42958] "SUBSCRIBE" "PubSubTest180"
1446773145.012000 [0 127.0.0.1:42779] "PUBLISH" "PubSubTest180" "3"
1446773145.012180 [0 127.0.0.1:42779] "PUBLISH" "PubSubTest180" "10000"
1446773145.016091 [0 127.0.0.1:42779] "PUBLISH" "PubSubTest181" "3"
1446773145.016143 [0 127.0.0.1:42959] "AUTH" "foobared"
1446773145.016313 [0 127.0.0.1:42779] "PUBLISH" "PubSubTest181" "10000"
1446773145.016360 [0 127.0.0.1:42959] "SUBSCRIBE" "PubSubTest181"
1446773145.018781 [0 127.0.0.1:42779] "PUBLISH" "PubSubTest182" "3"
1446773145.019018 [0 127.0.0.1:42779] "PUBLISH" "PubSubTest182" "10000"
1446773145.021332 [0 127.0.0.1:42779] "PUBLISH" "PubSubTest183" "3"
1446773145.021788 [0 127.0.0.1:42779] "PUBLISH" "PubSubTest183" "10000"
1446773145.024136 [0 127.0.0.1:42779] "PUBLISH" "PubSubTest184" "3"
1446773145.024309 [0 127.0.0.1:42779] "PUBLISH" "PubSubTest184" "10000"
1446773145.026661 [0 127.0.0.1:42779] "PUBLISH" "PubSubTest185" "3"
1446773145.026866 [0 127.0.0.1:42779] "PUBLISH" "PubSubTest185" "10000"
1446773145.029221 [0 127.0.0.1:42779] "PUBLISH" "PubSubTest186" "3"
1446773145.029374 [0 127.0.0.1:42779] "PUBLISH" "PubSubTest186" "10000"
1446773145.031828 [0 127.0.0.1:42779] "PUBLISH" "PubSubTest187" "3"
1446773145.032033 [0 127.0.0.1:42779] "PUBLISH" "PubSubTest187" "10000"
The culprit being PubSubTest181 where it subscribes after the publish rather than before. Increasing the sleep before the publish from 2ms -> 10ms should alleviate this though will now extend the total tests running time by 16s (when doing so for the other similar test also).