disable all checks on revert commits

For QB08-047.

hooks/git.py

@@ -504,3 +504,22 @@ def diff_tree(*args, **kwargs):
                        filename))
 
     return result
+
+
+def is_revert_commit(rev):
+    """Return True if the given commit appears to be a revert commit.
+
+    PARAMETERS
+        rev: A commit revision (string with the commit's SHA1 or reference
+            name).
+    """
+    # We detect such commits by searching for specific patterns that
+    # the "git revert" command automatically includes in the default
+    # revision log of such commits, hoping that a user is not deleting
+    # them afterwards.
+    raw_revlog = git.log('-1', rev, pretty='format:%B')
+    if 'This reverts commit' in raw_revlog:
+        return True
+
+    # No recognizable pattern. Probably not a revert commit.
+    return False

hooks/updates/__init__.py

@@ -3,7 +3,7 @@
 from config import git_config, SUBJECT_MAX_SUBJECT_CHARS
 from errors import InvalidUpdate
 from git import (git, get_object_type, is_null_rev, commit_parents,
-                 commit_rev)
+                 commit_rev, is_revert_commit)
 from os.path import expanduser, isfile, getmtime
 from pre_commit_checks import (check_revision_history, style_check_commit,
                                check_filename_collisions,
@@ -231,7 +231,18 @@ class AbstractUpdate(object):
             # handled by the __no_cvs_check_user_override method.
             return
 
+        # Create a list of commits that were added, but with revert
+        # commits being filtered out. We have decided that revert commits
+        # should not be subject to any check (QB08-047).  This allows
+        # users to quickly revert a commit if need be, without having
+        # to worry about bumping into any check of any kind.
         added = self.added_commits
+        for commit in added:
+            if is_revert_commit(commit.rev):
+                debug('revert commit detected,'
+                      ' all checks disabled for this commit: %s' % commit.rev)
+                added.remove(commit)
+
         if not added:
             # There are no new commits, so nothing further to check.
             return

testsuite/tests/QB08-047__push_revert_commit/bare_repo_config

@@ -0,0 +1,4 @@
+[core]
+	repositoryformatversion = 0
+	filemode = true
+	bare = true

testsuite/tests/QB08-047__push_revert_commit/cvs_check.py

@@ -0,0 +1,16 @@
+#! /usr/bin/env python
+"""A dummy cvs_check program that FAILs all files.
+"""
+import sys
+
+# To help with testing, print a trace containing the name of the module
+# and the names of the files being checked.
+print "cvs_check: %s < %s" % (
+    ' '.join(["`%s'" % arg for arg in sys.argv[1:]]),
+    ' '.join(["`%s'" % arg for arg in sys.stdin.read().splitlines(False)]))
+
+filenames = sys.stdin.read().splitlines(False)
+
+print >> sys.stderr, \
+    'ERROR: %s: Copyright year in header is not up to date' % filenames[0]
+sys.exit(1)

testsuite/tests/QB08-047__push_revert_commit/hooks_config

@@ -0,0 +1,4 @@
+[hooks]
+        from-domain = adacore.com
+        mailinglist = git-hooks-ci@example.com
+        tn-required = true

testsuite/tests/QB08-047__push_revert_commit/test.py

@@ -0,0 +1,96 @@
+from support import *
+
+class TestRun(TestCase):
+    def test_push_commit_on_master(self):
+        """Try pushing one single-file commit on master.
+
+        This is just to verify that revision-log checks are enabled,
+        and in particular that we get an error if the TN is missing.
+        That way, we know that our repository is correctly configured
+        in terms of requiring TNs in the revision log and should
+        normally reject commits that don't follow this rule.
+        """
+        cd ('%s/repo' % TEST_DIR)
+
+        # Push master to the `origin' remote.  The delta should be one
+        # commit with one file being modified.
+        p = Run('git push origin master'.split())
+        expected_out = """\
+remote: *** The following commit is missing a ticket number inside
+remote: *** its revision history.  If the change is sufficiently
+remote: *** minor that a ticket number is not meaningful, please use
+remote: *** the word "no-tn-check" in place of a ticket number.
+remote: ***
+remote: *** commit a60540361d47901d3fe254271779f380d94645f7
+remote: *** Subject: Updated a.
+remote: error: hook declined to update refs/heads/master
+To ../bare/repo.git
+ ! [remote rejected] master -> master (hook declined)
+error: failed to push some refs to '../bare/repo.git'
+"""
+
+        self.assertNotEqual(p.status, 0, p.image)
+        self.assertRunOutputEqual(p, expected_out)
+
+    def test_push_commit_on_revert(self):
+        """Try pushing one single-file commit on revert.
+
+        This verifies that all checks are disabled when pushing
+        a commit which has been created using "git revert". In
+        particular, this commit violates a number of requirements
+        in the revision log. And the cvs_check.py script is also
+        set up to always return an error, so this will allow us
+        to verify that no file is style-checked.
+        """
+        cd ('%s/repo' % TEST_DIR)
+
+        # Push master to the `origin' remote.  The delta should be one
+        # commit with one file being modified.
+        p = Run('git push origin revert'.split())
+        expected_out = """\
+remote: DEBUG: Content-Type: text/plain; charset="us-ascii"
+remote: MIME-Version: 1.0
+remote: Content-Transfer-Encoding: 7bit
+remote: From: Test Suite <testsuite@adacore.com>
+remote: To: git-hooks-ci@example.com
+remote: Bcc: file-ci@gnat.com
+remote: Subject: [repo/revert] Revert "New file: a."
+remote: X-Act-Checkin: repo
+remote: X-Git-Author: Joel Brobecker <brobecker@adacore.com>
+remote: X-Git-Refname: refs/heads/revert
+remote: X-Git-Oldrev: d065089ff184d97934c010ccd0e7e8ed94cb7165
+remote: X-Git-Newrev: d669d669fcbdeab1eedf9756ce1ef5a62c4f97db
+remote:
+remote: commit d669d669fcbdeab1eedf9756ce1ef5a62c4f97db
+remote: Author: Joel Brobecker <brobecker@adacore.com>
+remote: Date:   Thu Nov 9 06:05:21 2017 -0800
+remote:
+remote:     Revert "New file: a."
+remote:
+remote:     This reverts commit d065089ff184d97934c010ccd0e7e8ed94cb7165.
+remote:
+remote:     No TN included as we want to verify that revert commits don't go through any check of any kind (including lines too long like this one).
+remote:
+remote: Diff:
+remote: ---
+remote:  a | 3 ---
+remote:  1 file changed, 3 deletions(-)
+remote:
+remote: diff --git a/a b/a
+remote: deleted file mode 100644
+remote: index 01d0f12..0000000
+remote: --- a/a
+remote: +++ /dev/null
+remote: @@ -1,3 +0,0 @@
+remote: -Some file.
+remote: -Second line.
+remote: -Third line.
+To ../bare/repo.git
+   d065089..d669d66  revert -> revert
+"""
+
+        self.assertEqual(p.status, 0, p.image)
+        self.assertRunOutputEqual(p, expected_out)
+
+if __name__ == '__main__':
+    runtests()