tests/test-hghave.t

verify: add a config option to skip certain flag processors

Previously, "hg verify" verifies everything, which could be undesirable when
there are expensive flag processor contents.

This patch adds a "verify.skipflags" developer config. A flag processor will
be skipped if (flag & verify.skipflags) == 0.

In the LFS usecase, that means "hg verify --config verify.skipflags=8192"
will not download all LFS blobs, which could be too large to be stored
locally.

Note: "renamed" is also skipped since its default implementation may call
filelog.data() which will trigger the flag processor.

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
  $ run-tests.py $HGTEST_RUN_TESTS_PURE test-hghaveaddon.t
  .
  # Ran 1 tests, 0 skipped, 0 warned, 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]