Stats Methods


The tester stats methods provide a library of functions which are typically used in test scripts for the IN Tester for the purpose of validating statistics counters.

Tester helper methods are accessed via the “n2.n2svcd.tester.stats” module:

    local stats = require "n2.n2svcd.tester.stats"

.delta [Synchronous]

The delta method uses the n2svcd.management_summary method to fetch an application’s current statistics values.

When called repeatedly, it computes a delta of the statistics counter changes since the previous call.

This allows a test script to validate that the application’s statistics counters have changed by the expected amount as a result of the intermediate test actions.

The parameters for this method are:

Parameter Type Description
app_name String [Required] The name of the application whose management summary we are requesting.
This must be a real application name, it cannot be a virtual (load-share/failover) app name.
previous Table The checkpoint object from the previous invocation.

The delta method returns two result values.

Parameter Type Description
deltas Table A table keyed by statistics names returned from the management_summary.
The value for each entry is the delta from the previous checkpoint.
current Table The checkpoint object which should be passed into the next invocation of this method.


  local delta, checkpoint

  delta, checkpoint = ('Logic', checkpoint)

    [intermediate test processing goes here]

  delta, checkpoint = ('Logic', checkpoint)
  n2svcd.match_integer ('instance.start', delta['instance.start'], 3)
  n2svcd.match_integer ('instance.shutdown', delta['instance.shutdown'], 3)
  n2svcd.match_integer ('messages.rcvd', delta['messages.rcvd'], 1)
  n2svcd.match_integer ('messages.sent', delta['messages.sent'], 2)