tests/test-imports-checker.t

windows: add a method to convert Unix style command lines to Windows style

This started as a copy/paste of `os.path.expandvars()`, but limited to a given
dictionary of variables, converting `foo = foo + bar` to `foo += bar`, and
adding 'b' string prefixes.  Then code was added to make sure that a value being
substituted in wouldn't itself be expanded by cmd.exe.  But that left
inconsistent results between `$var1` and `%var1%` when its value was '%foo%'-
since neither were touched, `$var1` wouldn't expand but `%var1%` would.  So
instead, this just converts the Unix style to Windows style (if the variable
exists, because Windows will leave `%missing%` as-is), and lets cmd.exe do its
thing.

I then dropped the %% -> % conversion (because Windows doesn't do this), and
added the ability to escape the '$' with '\'.  The escape character is dropped,
for consistency with shell handling.

After everything seemed stable and working, running the whole test suite flagged
a problem near the end of test-bookmarks.t:1069.  The problem is cmd.exe won't
pass empty variables to its child, so defined but empty variables are now
skipped.  I can't think of anything better, and it seems like a pre-existing
violation of the documentation, which calls out that HG_OLDNODE is empty on
bookmark creation.

Future additions could potentially be replacing strong quotes with double quotes
(cmd.exe doesn't know what to do with the former), escaping a double quote, and
some tilde expansion via os.path.expanduser().  I've got some doubts about
replacing the strong quotes in case sh.exe is run, but it seems like the right
thing to do the vast majority of the time.  The original form of this was
discussed about a year ago[1].

[1] https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-July/100735.html

#require test-repo

  $ . "$TESTDIR/helpers-testrepo.sh"
  $ testrepohgenv
  $ import_checker="$TESTDIR"/../contrib/import-checker.py

Run the doctests from the import checker, and make sure
it's working correctly.
  $ TERM=dumb
  $ export TERM
  $ $PYTHON -m doctest $import_checker

Run additional tests for the import checker

  $ mkdir testpackage
  $ touch testpackage/__init__.py

  $ cat > testpackage/multiple.py << EOF
  > from __future__ import absolute_import
  > import os, sys
  > EOF

  $ cat > testpackage/unsorted.py << EOF
  > from __future__ import absolute_import
  > import sys
  > import os
  > EOF

  $ cat > testpackage/stdafterlocal.py << EOF
  > from __future__ import absolute_import
  > from . import unsorted
  > import os
  > EOF

  $ cat > testpackage/requirerelative.py << EOF
  > from __future__ import absolute_import
  > import testpackage.unsorted
  > EOF

  $ cat > testpackage/importalias.py << EOF
  > from __future__ import absolute_import
  > import ui
  > EOF

  $ cat > testpackage/relativestdlib.py << EOF
  > from __future__ import absolute_import
  > from .. import os
  > EOF

  $ cat > testpackage/symbolimport.py << EOF
  > from __future__ import absolute_import
  > from .unsorted import foo
  > EOF

  $ cat > testpackage/latesymbolimport.py << EOF
  > from __future__ import absolute_import
  > from . import unsorted
  > from mercurial.node import hex
  > EOF

  $ cat > testpackage/multiplegroups.py << EOF
  > from __future__ import absolute_import
  > from . import unsorted
  > from . import more
  > EOF

  $ mkdir testpackage/subpackage
  $ cat > testpackage/subpackage/levelpriority.py << EOF
  > from __future__ import absolute_import
  > from . import foo
  > from .. import parent
  > EOF

  $ touch testpackage/subpackage/foo.py
  $ cat > testpackage/subpackage/__init__.py << EOF
  > from __future__ import absolute_import
  > from . import levelpriority  # should not cause cycle
  > EOF

  $ cat > testpackage/subpackage/localimport.py << EOF
  > from __future__ import absolute_import
  > from . import foo
  > def bar():
  >     # should not cause "higher-level import should come first"
  >     from .. import unsorted
  >     # but other errors should be detected
  >     from .. import more
  >     import testpackage.subpackage.levelpriority
  > EOF

  $ cat > testpackage/importmodulefromsub.py << EOF
  > from __future__ import absolute_import
  > from .subpackage import foo  # not a "direct symbol import"
  > EOF

  $ cat > testpackage/importsymbolfromsub.py << EOF
  > from __future__ import absolute_import
  > from .subpackage import foo, nonmodule
  > EOF

  $ cat > testpackage/sortedentries.py << EOF
  > from __future__ import absolute_import
  > from . import (
  >     foo,
  >     bar,
  > )
  > EOF

  $ cat > testpackage/importfromalias.py << EOF
  > from __future__ import absolute_import
  > from . import ui
  > EOF

  $ cat > testpackage/importfromrelative.py << EOF
  > from __future__ import absolute_import
  > from testpackage.unsorted import foo
  > EOF

  $ mkdir testpackage2
  $ touch testpackage2/__init__.py

  $ cat > testpackage2/latesymbolimport.py << EOF
  > from __future__ import absolute_import
  > from testpackage import unsorted
  > from mercurial.node import hex
  > EOF

# Shadowing a stdlib module to test "relative import of stdlib module" is
# allowed if the module is also being checked

  $ mkdir email
  $ touch email/__init__.py
  $ touch email/errors.py
  $ cat > email/utils.py << EOF
  > from __future__ import absolute_import
  > from . import errors
  > EOF

  $ $PYTHON "$import_checker" testpackage*/*.py testpackage/subpackage/*.py \
  >   email/*.py
  testpackage/importalias.py:2: ui module must be "as" aliased to uimod
  testpackage/importfromalias.py:2: ui from testpackage must be "as" aliased to uimod
  testpackage/importfromrelative.py:2: import should be relative: testpackage.unsorted
  testpackage/importfromrelative.py:2: direct symbol import foo from testpackage.unsorted
  testpackage/importsymbolfromsub.py:2: direct symbol import nonmodule from testpackage.subpackage
  testpackage/latesymbolimport.py:3: symbol import follows non-symbol import: mercurial.node
  testpackage/multiple.py:2: multiple imported names: os, sys
  testpackage/multiplegroups.py:3: multiple "from . import" statements
  testpackage/relativestdlib.py:2: relative import of stdlib module
  testpackage/requirerelative.py:2: import should be relative: testpackage.unsorted
  testpackage/sortedentries.py:2: imports from testpackage not lexically sorted: bar < foo
  testpackage/stdafterlocal.py:3: stdlib import "os" follows local import: testpackage
  testpackage/subpackage/levelpriority.py:3: higher-level import should come first: testpackage
  testpackage/subpackage/localimport.py:7: multiple "from .. import" statements
  testpackage/subpackage/localimport.py:8: import should be relative: testpackage.subpackage.levelpriority
  testpackage/symbolimport.py:2: direct symbol import foo from testpackage.unsorted
  testpackage/unsorted.py:3: imports not lexically sorted: os < sys
  testpackage2/latesymbolimport.py:3: symbol import follows non-symbol import: mercurial.node
  [1]