anchor.diff:    };
   
     testScript = ''
  -    subtest "timers exist", sub {
  +    # Check configuration
  +    subtest "Timers exist", sub {
         $cass0->succeed("systemctl list-timers | grep cassandra-full-repair.timer");
         $cass0->succeed("systemctl list-timers | grep cassandra-incremental-repair.timer");
       };
  -    subtest "can connect via cqlsh", sub {
  +    subtest "Can connect via cqlsh", sub {
         $cass0->waitForUnit("cassandra.service");
         $cass0->waitUntilSucceeds("nc -z cass0 9042");
         $cass0->succeed("echo 'show version;' | cqlsh cass0");
       };
  -    subtest "nodetool is operational", sub {
  +    subtest "Nodetool is operational", sub {
         $cass0->waitForUnit("cassandra.service");
         $cass0->waitUntilSucceeds("nc -z localhost 7199");
         $cass0->succeed("nodetool status --resolve-ip | egrep '^UN[[:space:]]+cass0'");
       };
  -    subtest "bring up cluster", sub {
  +
  +    # Check cluster interaction
  +    subtest "Bring up cluster", sub {
         $cass1->waitForUnit("cassandra.service");
         $cass1->waitUntilSucceeds("nodetool status | egrep -c '^UN' | grep 2");
         $cass0->succeed("nodetool status --resolve-ip | egrep '^UN[[:space:]]+cass1'");
       };
  -    subtest "break and fix node", sub {
  +    subtest "Break and fix node", sub {
         $cass1->block;
         $cass0->waitUntilSucceeds("nodetool status --resolve-ip | egrep -c '^DN[[:space:]]+cass1'");
         $cass0->succeed("nodetool status | egrep -c '^UN'  | grep 1");
  
positive.code:       $cass1->waitUntilSucceeds("nodetool status | egrep -c '^UN'  | grep 2");
        $cass0->succeed("nodetool status | egrep -c '^UN'  | grep 2");
      };
      subtest "replace crashed node", sub {
        $cass1->crash;
        $cass2->waitForUnit("cassandra.service");
        $cass0->waitUntilFails("nodetool status --resolve-ip | egrep '^UN[[:space:]]+cass1'");
  
negative.code:         };
        package = testPackage;
      };
    nodeCfg = ipAddress: extra: {pkgs, config, ...}:
      { environment.systemPackages = [ testPackage ];
        networking.firewall.enable = false;
        services.cassandra = cassandraCfg ipAddress // extra;
        virtualisation.memorySize = 1024;
      };
  in
  