tests/test-hghave.t

revset: extract parsing logic out of formatspec

We want to be able to perform better handling of some input when running
revset (eg: `repo.revs("%ld", somerevs)`). The first step is to be able to
access some of the parsed content before it gets substituted. There are many
possible different substitutions, we'll add support for them gradually.

In this changeset we support none, we just split some logic in a sub function
as a preparatory step.

  $ . "$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 -j 1 \
  >    $HGTEST_RUN_TESTS_PURE test-hghaveaddon.t \
  > )
  running 1 tests using 1 parallel processes 
  .
  # 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 <<NO_CHECK_EOF
  > importing this file should cause syntax error
  > NO_CHECK_EOF

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