Toxiproxy repoduction Install toxiproxy on your machine (brew or whatever package manager you have) Open a terminal terminal and run toxiproxy-server & toxiproxy-cli create mongod_primary -l localhost:12345 -u localhost:31000 Create a replicaset with one primary and 2 secondaries with ports 31000, 31001, 31002 where the primary has priority 100. { "_id" : "rs" , "version" : 1, "members" : [ { "_id" : 0, "host" : "localhost:12345" , "priority" : 100 }, { "_id" : 1, "host" : "localhost:31001" , "priority" : 1 }, { "_id" : 2, "host" : "localhost:31002" , "priority" : 1 } ] } Wait for election to finish and a primary to be selected. Now throw the primary in the black hole. toxiproxy-cli toxic add mongod_primary -t timeout -a timeout=0 --upstream toxiproxy-cli toxic add mongod_primary -t timeout -a timeout=0 --downstream Watch as the new primary is elected and then the flapping starts with new elections happening ever X seconds. You can turn off the toxics by running the following commands toxiproxy-cli toxic remove mongod_primary -n timeout_downstream toxiproxy-cli toxic remove mongod_primary -n timeout_upstream