tests/test-contrib-emacs.t

dirstate-v2: Add `hg debugupgraderepo` command support

This command changes changes the file formats used inside an existing
repository to what they would be in a new repository with the current config.

For example:

    hg debugupgraderepo --config format.exp-dirstate-v2=1 --run
    hg debugupgraderepo --config format.exp-dirstate-v2=0 --run

If a repository has a dirstate in v1 format, the first command would upgrade it
to dirstate-v2. Conversely, if a repository has a dirstate in v2 format, the
second command would downgrade it to v1. (Both may also run some unrelated
upgrades.)

Since `format.exp-dirstate-v2` is currently disabled by default, not specifying
it in `--config` or any configuration file would result in the second command.

Differential Revision: https://phab.mercurial-scm.org/D10769

#require emacs
  $ emacs -q -no-site-file -batch -l $TESTDIR/../contrib/hg-test-mode.el \
  >  -f ert-run-tests-batch-and-exit
  Running 1 tests (*) (glob)
     passed  1/1  hg-test-mode--compilation-mode-support* (glob)
  
  Ran 1 tests, 1 results as expected* (glob)