tests/test-permissions.t

tests: add test for Python 3 compatibility

Python 3 is inevitable. There have been incremental movements towards
converting the code base to be Python 3 compatible. Unfortunately, we
don't have any tests that look for Python 3 compatibility. This patch
changes that.

We introduce a check-py3-compat.py script whose role is to verify
Python 3 compatibility of the files passed in. We add a test that
calls this script with all .py files from the source checkout.

The script currently only verifies that absolute_import and
print_function are used. These are the low hanging fruits for Python
compatbility. Over time, we can include more checks, including
verifying we're able to load each Python file with Python 3. You
have to start somewhere.

Accepting this patch means that all new .py files must have
absolute_import and print_function (if "print" is used) to avoid
a new warning about Python 3 incompatibility. We've already
converted several files to use absolute_import and print_function
is in the same boat, so I don't think this is such a radical
proposition.

#require unix-permissions no-root

  $ hg init t
  $ cd t

  $ echo foo > a
  $ hg add a

  $ hg commit -m "1"

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 1 changesets, 1 total revisions

  $ chmod -r .hg/store/data/a.i

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  abort: Permission denied: $TESTTMP/t/.hg/store/data/a.i
  [255]

  $ chmod +r .hg/store/data/a.i

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 1 changesets, 1 total revisions

  $ chmod -w .hg/store/data/a.i

  $ echo barber > a
  $ hg commit -m "2"
  trouble committing a!
  abort: Permission denied: $TESTTMP/t/.hg/store/data/a.i
  [255]

  $ chmod -w .

  $ hg diff --nodates
  diff -r 2a18120dc1c9 a
  --- a/a
  +++ b/a
  @@ -1,1 +1,1 @@
  -foo
  +barber

  $ chmod +w .

  $ chmod +w .hg/store/data/a.i
  $ mkdir dir
  $ touch dir/a
  $ hg status
  M a
  ? dir/a
  $ chmod -rx dir
  $ hg status
  dir: Permission denied
  M a

Reenable perm to allow deletion:

  $ chmod +rx dir

  $ cd ..