TEST_F(TopoCoordTest, ArbiterNotIncludedInMajorityReplicatedConfigChecks) {
    // Config with only one data-bearing node only needs one node to majority replicate config.
    updateConfig(BSON("_id"
                      << "rs0"
                      << "version" << 2 << "term" << 0 << "members"
                      << BSON_ARRAY(BSON("_id" << 0 << "host"
                                               << "host0:27017")
                                    << BSON("_id" << 1 << "host"
                                                  << "host1:27017"
                                                  << "priority" << 0 << "votes" << 0)
                                    << BSON("_id" << 2 << "host"
                                                  << "host2:27017"
                                                  << "priority" << 0 << "votes" << 0)
                                    << BSON("_id" << 3 << "host"
                                                  << "host3:27017"
                                                  << "priority" << 0 << "votes" << 1)
                                    << BSON("_id" << 4 << "host"
                                                  << "host4:27017"
                                                  << "priority" << 0 << "votes" << 1))),
                 0);

    // makeSelfPrimary() doesn't actually conduct a true election, so the term will still be 0.
    makeSelfPrimary();

    // Simulate a heartbeat to one of the other nodes.
    getTopoCoord().prepareHeartbeatRequestV1(now(), "rs0", HostAndPort("host1"));
    // Simulate heartbeat response from host1. This will call setUpValues, which will update the
    // memberData for host1.
    ReplSetHeartbeatResponse hb3;
    hb3.setConfigVersion(2);
    hb3.setConfigTerm(0);
    hb3.setState(MemberState::RS_SECONDARY);
    StatusWith<ReplSetHeartbeatResponse> hbResponse3 = StatusWith<ReplSetHeartbeatResponse>(hb3);
    now() += Milliseconds(1);
    getTopoCoord().processHeartbeatResponse(
            now(), Milliseconds(1), HostAndPort("host1"), hbResponse3);

    // Simulate a heartbeat to one of the other nodes.
    getTopoCoord().prepareHeartbeatRequestV1(now(), "rs0", HostAndPort("host2"));
    // Simulate heartbeat response from host1. This will call setUpValues, which will update the
    // memberData for host1.
    ReplSetHeartbeatResponse hb4;
    hb4.setConfigVersion(2);
    hb4.setConfigTerm(0);
    hb4.setState(MemberState::RS_SECONDARY);
    StatusWith<ReplSetHeartbeatResponse> hbResponse4 = StatusWith<ReplSetHeartbeatResponse>(hb4);
    now() += Milliseconds(1);
    getTopoCoord().processHeartbeatResponse(
            now(), Milliseconds(1), HostAndPort("host2"), hbResponse4);

    // Currently, only the primary has config 2 (the initial config). But, since arbiters do not
    // count towards the config majority, haveMajorityReplicatedConfig() should still return true.
    ASSERT_FALSE(getTopoCoord().haveMajorityReplicatedConfig());
}