tests/test-hghave.t

wireproto: disallow commands handlers for multiple transport versions

I think it will be more trouble than it is worth to code version 1
and version 2 command handlers to the same interface. It will feel
awkward to shoehorn functionality into e.g. the version 1 protocol
handler interface. This would likely constrain the ability for version
2 to evolve.

Previous commits introduced a clean separation between command handlers
for version 1 and version 2 transports. This commit reinforces that
separation by dropping support for having a single command handler
service both version 1 and version 2 transports.

Differential Revision: https://phab.mercurial-scm.org/D3208

  $ . "$TESTDIR/helpers-testrepo.sh"

Testing that hghave does not crash when checking features

  $ hghave --test-features 2>/dev/null

Testing hghave extensibility for third party tools

  $ cat > hghaveaddon.py <<EOF
  > import hghave
  > @hghave.check("custom", "custom hghave feature")
  > def has_custom():
  >     return True
  > EOF

(invocation via run-tests.py)

  $ cat > test-hghaveaddon.t <<EOF
  > #require custom
  >   $ echo foo
  >   foo
  > EOF
  $ ( \
  > testrepohgenv; \
  > $PYTHON $TESTDIR/run-tests.py $HGTEST_RUN_TESTS_PURE test-hghaveaddon.t \
  > )
  .
  # Ran 1 tests, 0 skipped, 0 failed.

(invocation via command line)

  $ unset TESTDIR
  $ hghave custom

(terminate with exit code 2 at failure of importing hghaveaddon.py)

  $ rm hghaveaddon.*
  $ cat > hghaveaddon.py <<EOF
  > importing this file should cause syntax error
  > EOF

  $ hghave custom
  failed to import hghaveaddon.py from '.': invalid syntax (hghaveaddon.py, line 1)
  [2]