import-checker: establish modern import convention
We introduce a new convention for declaring imports and enforce it via
the import checker script.
The new convention is only active when absolute imports are used, which is
currently nowhere. Keying off "from __future__ import absolute_import" to
engage the new import convention seems like the easiest solution. It is
also beneficial for Mercurial to use this mode because it means less work
and ambiguity for the importer and potentially better performance due to
fewer stat() system calls because the importer won't look for modules in
relative paths unless explicitly asked.
Once all files are converted to use absolute import, we can refactor
this code to again only have a single import convention and we can
require use of absolute import in the style checker.
The rules for the new convention are documented in the docstring of the
added function. Tests have been added to test-module-imports.t. Some
tests are sensitive to newlines and source column position, which makes
docstring testing difficult and/or impossible.
Create a repository:
$ hg config
defaults.backout=-d "0 0"
defaults.commit=-d "0 0"
defaults.shelve=--date "0 0"
defaults.tag=-d "0 0"
devel.all-warnings=true
largefiles.usercache=$TESTTMP/.cache/largefiles (glob)
ui.slash=True
ui.interactive=False
ui.mergemarkers=detailed
ui.promptecho=True
$ hg init t
$ cd t
Make a changeset:
$ echo a > a
$ hg add a
$ hg commit -m test
This command is ancient:
$ hg history
changeset: 0:acb14030fe0a
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: test
Verify that updating to revision 0 via commands.update() works properly
$ cat <<EOF > update_to_rev0.py
> from mercurial import ui, hg, commands
> myui = ui.ui()
> repo = hg.repository(myui, path='.')
> commands.update(myui, repo, rev=0)
> EOF
$ hg up null
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ python ./update_to_rev0.py
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg identify -n
0
Poke around at hashes:
$ hg manifest --debug
b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644 a
$ hg cat a
a
Verify should succeed:
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
At the end...
$ cd ..