Implement merge-files only using @bukzor's method.

pre_commit/commands.py

@@ -147,6 +147,8 @@ def clean(runner):
 def _run_single_hook(runner, repository, hook_id, args, write):
     if args.all_files:
         get_filenames = git.get_all_files_matching
+    elif git.is_in_merge_conflict():
+        get_filenames = git.get_conflicted_files_matching
     else:
         get_filenames = git.get_staged_files_matching
 

pre_commit/git.py

@@ -1,4 +1,5 @@
 import functools
+import logging
 import os
 import os.path
 import re
@@ -7,7 +8,11 @@ from plumbum import local
 from pre_commit.util import memoize_by_cwd
 
 
-def _get_root_new():
+logger = logging.getLogger('pre_commit')
+
+
+@memoize_by_cwd
+def get_root():
     path = os.getcwd()
     while len(path) > 1:
         if os.path.exists(os.path.join(path, '.git')):
@@ -17,9 +22,32 @@ def _get_root_new():
     raise AssertionError('called from outside of the gits')
 
 
+def is_in_merge_conflict():
+    return os.path.exists(os.path.join('.git', 'MERGE_MSG'))
+
+
+def parse_merge_msg_for_conflicts(merge_msg):
+    # Conflicted files start with tabs
+    return [
+        line.strip() for line in merge_msg.splitlines() if line.startswith('\t')
+    ]
+
+
 @memoize_by_cwd
-def get_root():
-    return _get_root_new()
+def get_conflicted_files():
+    # Need to get the conflicted files from the MERGE_MSG because they could
+    # have resolved the conflict by choosing one side or the other
+    merge_msg = open(os.path.join('.git', 'MERGE_MSG')).read()
+    merge_conflict_filenames = parse_merge_msg_for_conflicts(merge_msg)
+
+    # This will get the rest of the changes made after the merge.
+    # If they resolved the merge conflict by choosing a mesh of both sides
+    # this will also include the conflicted files
+    tree_hash = local['git']['write-tree']().strip()
+    merge_diff_filenames = local['git'][
+        'diff', '-m', tree_hash, 'HEAD', 'MERGE_HEAD', '--name-only',
+    ]().splitlines()
+    return set(merge_conflict_filenames) | set(merge_diff_filenames)
 
 
 @memoize_by_cwd
@@ -52,3 +80,4 @@ def get_files_matching(all_file_list_strategy):
 
 get_staged_files_matching = get_files_matching(get_staged_files)
 get_all_files_matching = get_files_matching(get_all_files)
+get_conflicted_files_matching = get_files_matching(get_conflicted_files)

tests/commands_test.py

@@ -283,26 +283,6 @@ def test_has_unmerged_paths(output, expected):
     assert commands._has_unmerged_paths(mock_runner) is expected
 
 
-@pytest.yield_fixture
-def in_merge_conflict(repo_with_passing_hook):
-    local['git']['add', C.CONFIG_FILE]()
-    local['git']['commit', '-m' 'add hooks file']()
-    local['git']['clone', '.', 'foo']()
-    with local.cwd('foo'):
-        local['git']['checkout', 'origin/master', '-b', 'foo']()
-        with open('conflict_file', 'w') as conflict_file:
-            conflict_file.write('herp\nderp\n')
-        local['git']['add', 'conflict_file']()
-        local['git']['commit', '-m', 'conflict_file']()
-        local['git']['checkout', 'origin/master', '-b', 'bar']()
-        with open('conflict_file', 'w') as conflict_file:
-            conflict_file.write('harp\nddrp\n')
-        local['git']['add', 'conflict_file']()
-        local['git']['commit', '-m', 'conflict_file']()
-        local['git']['merge', 'foo'](retcode=None)
-        yield os.path.join(repo_with_passing_hook, 'foo')
-
-
 def test_merge_conflict(in_merge_conflict):
     ret, printed = _do_run(in_merge_conflict, _get_opts())
     assert ret == 1

tests/conftest.py

@@ -1,5 +1,7 @@
 from __future__ import absolute_import
 
+import os
+import os.path
 import pytest
 import time
 import yaml
@@ -126,3 +128,29 @@ def repo_with_passing_hook(config_for_script_hooks_repo, empty_git_dir):
 def repo_with_failing_hook(failing_hook_repo, empty_git_dir):
     _make_repo_from_configs(_make_config(failing_hook_repo, 'failing_hook', ''))
     yield empty_git_dir
+
+
+@pytest.yield_fixture
+def in_merge_conflict(repo_with_passing_hook):
+    local['git']['add', C.CONFIG_FILE]()
+    local['git']['commit', '-m' 'add hooks file']()
+    local['git']['clone', '.', 'foo']()
+    with local.cwd('foo'):
+        local['git']['checkout', 'origin/master', '-b', 'foo']()
+        with open('conflict_file', 'w') as conflict_file:
+            conflict_file.write('herp\nderp\n')
+        local['git']['add', 'conflict_file']()
+        with open('foo_only_file', 'w') as foo_only_file:
+            foo_only_file.write('foo')
+        local['git']['add', 'foo_only_file']()
+        local['git']['commit', '-m', 'conflict_file']()
+        local['git']['checkout', 'origin/master', '-b', 'bar']()
+        with open('conflict_file', 'w') as conflict_file:
+            conflict_file.write('harp\nddrp\n')
+        local['git']['add', 'conflict_file']()
+        with open('bar_only_file', 'w') as bar_only_file:
+            bar_only_file.write('bar')
+        local['git']['add', 'bar_only_file']()
+        local['git']['commit', '-m', 'conflict_file']()
+        local['git']['merge', 'foo'](retcode=None)
+        yield os.path.join(repo_with_passing_hook, 'foo')

tests/git_test.py

@@ -14,6 +14,14 @@ def test_get_root(empty_git_dir):
         assert git.get_root() == empty_git_dir
 
 
+def test_is_in_merge_conflict(empty_git_dir):
+    assert git.is_in_merge_conflict() is False
+
+
+def test_is_not_in_merge_conflict(in_merge_conflict):
+    assert git.is_in_merge_conflict() is True
+
+
 @pytest.fixture
 def get_files_matching_func():
     def get_filenames():
@@ -57,3 +65,48 @@ def test_does_not_include_deleted_fileS(get_files_matching_func):
 def test_exclude_removes_files(get_files_matching_func):
     ret = get_files_matching_func('', '\\.py$')
     assert ret == set(['hooks.yaml'])
+
+
+def resolve_conflict():
+    with open('conflict_file', 'w') as conflicted_file:
+        conflicted_file.write('herp\nderp\n')
+    local['git']['add', 'conflict_file']()
+
+
+def test_get_conflicted_files(in_merge_conflict):
+    resolve_conflict()
+    with open('other_file', 'w') as other_file:
+        other_file.write('oh hai')
+    local['git']['add', 'other_file']()
+
+    ret = set(git.get_conflicted_files())
+    assert ret == set(('conflict_file', 'other_file'))
+
+
+def test_get_conflicted_files_unstaged_files(in_merge_conflict):
+    # If they for whatever reason did pre-commit run --no-stash during a
+    # conflict
+    resolve_conflict()
+
+    # Make unstaged file.
+    with open('bar_only_file', 'w') as bar_only_file:
+        bar_only_file.write('new contents!\n')
+
+    ret = set(git.get_conflicted_files())
+    assert ret == set(('conflict_file',))
+
+
+MERGE_MSG = "Merge branch 'foo' into bar\n\nConflicts:\n\tconflict_file\n"
+OTHER_MERGE_MSG = MERGE_MSG + '\tother_conflict_file\n'
+
+
+@pytest.mark.parametrize(
+    ('input', 'expected_output'),
+    (
+        (MERGE_MSG, ['conflict_file']),
+        (OTHER_MERGE_MSG, ['conflict_file', 'other_conflict_file']),
+    ),
+)
+def test_parse_merge_msg_for_conflicts(input, expected_output):
+    ret = git.parse_merge_msg_for_conflicts(input)
+    assert ret == expected_output