[Ns-developers] Ns-3 Build Broken?

[craigdo@ee.washington.edu]

This is a message from your friendly neighborhood regression police.  There was a regression in ns-3-dev this afternoon and the
test-tcp-large-transfer regression test has promptly detected it (wow, it works :-).

If we're going to take regression testing seriously, I believe we should take this as seriously as if the build were broken.

So, the corollary is that just before you do a checkin you should run the regression tests.  Change into the regression directory
and type

  python regression.py

If you do this now, you will see a bunch of passing tests and then,

  ----------
  Traces differ in test: test-tcp-large-transfer
  Reference traces in directory: ns-3-dev-ref-traces/tcp-large-transfer.ref
  Traces in directory: traces
  Rerun regression test as: "python regression.py test-tcp-large-transfer"
  Then do "diff -u traces ns-3-dev-ref-traces/tcp-large-transfer.ref" for details
  ----------
  FAIL test-tcp-large-transfer

Now, this "failure" is most likely due to someone checking in a change this afternoon that added TCP delayed acks.

If you make a change like this, you'll need to update the reference traces for the new behavior.  All you have to do is to change
into the regression directory and run the test in question (here test-tcp-large-transfer) with the -g (generate) option, as in

  python regression.py -g test-tcp-large-transfer

This will write new reference traces into the proper place in the "ns-3-dev-ref-traces" directory.  In this case, look in the
directory,

  ns-3-dev-ref-traces/tcp-large-transfer.ref/

You need to that the new traces are what you expect to see given your change.  If you don't expect to see any changes, you may have
a real regression and you'll need to debug it.

Assuming that the new traces represent new expected behavior, you just need to push the new bits into the ns-3-dev-ref-traces
repository.

  cd ns-3-dev-ref-traces
  hg push ssh://code@code.nsnam.org//home/code/repos/ns-3-dev-ref-traces

That's all.

-- Craig