From b096c0b8f2074ec5c7e05528b27be4a1bf3df8d7 Mon Sep 17 00:00:00 2001
From: Pedro Algarvio <pedro@algarvio.me>
Date: Fri, 14 Dec 2018 12:29:52 +0000
Subject: [PATCH] Allow aliasing a hook and calling it by it's alias

---
 pre_commit/clientlib.py    | 18 +++++++++++++++++-
 pre_commit/commands/run.py |  8 ++++++--
 tests/commands/run_test.py | 26 ++++++++++++++++++++++++++
 3 files changed, 49 insertions(+), 3 deletions(-)

diff --git a/pre_commit/clientlib.py b/pre_commit/clientlib.py
index 2fa7b153..0722f5e6 100644
--- a/pre_commit/clientlib.py
+++ b/pre_commit/clientlib.py
@@ -29,6 +29,20 @@ def _make_argparser(filenames_help):
     return parser
 
 
+class OptionalAlias(object):
+
+    def check(self, dct):
+        if 'alias' in dct:
+            cfgv.check_string(dct['alias'])
+
+    def apply_default(self, dct):
+        if 'alias' not in dct:
+            dct['alias'] = dct['id']
+
+    def remove_default(self, dct):
+        pass
+
+
 MANIFEST_HOOK_DICT = cfgv.Map(
     'Hook', 'id',
 
@@ -36,6 +50,7 @@ MANIFEST_HOOK_DICT = cfgv.Map(
     cfgv.Required('name', cfgv.check_string),
     cfgv.Required('entry', cfgv.check_string),
     cfgv.Required('language', cfgv.check_one_of(all_languages)),
+    cfgv.OptionalNoDefault('alias', cfgv.check_string),
 
     cfgv.Optional(
         'files', cfgv.check_and(cfgv.check_string, cfgv.check_regex), '',
@@ -125,6 +140,7 @@ CONFIG_HOOK_DICT = cfgv.Map(
     'Hook', 'id',
 
     cfgv.Required('id', cfgv.check_string),
+    OptionalAlias(),
 
     # All keys in manifest hook dict are valid in a config hook dict, but
     # are optional.
@@ -133,7 +149,7 @@ CONFIG_HOOK_DICT = cfgv.Map(
     *[
         cfgv.OptionalNoDefault(item.key, item.check_fn)
         for item in MANIFEST_HOOK_DICT.items
-        if item.key != 'id'
+        if item.key not in ('id', 'alias')
     ]
 )
 CONFIG_REPO_DICT = cfgv.Map(
diff --git a/pre_commit/commands/run.py b/pre_commit/commands/run.py
index f2ff7b38..9cd3dfcf 100644
--- a/pre_commit/commands/run.py
+++ b/pre_commit/commands/run.py
@@ -257,13 +257,17 @@ def run(config_file, store, args, environ=os.environ):
         for repo in repositories(config, store):
             for _, hook in repo.hooks:
                 if (
-                    (not args.hook or hook['id'] == args.hook) and
+                    (not args.hook or hook['id'] == args.hook or (
+                        hook['alias'] and hook['alias'] == args.hook
+                    )) and
                     (not hook['stages'] or args.hook_stage in hook['stages'])
                 ):
                     repo_hooks.append((repo, hook))
 
         if args.hook and not repo_hooks:
-            output.write_line('No hook with id `{}`'.format(args.hook))
+            output.write_line(
+                'No hook with id or alias `{}`'.format(args.hook),
+            )
             return 1
 
         for repo in {repo for repo, _ in repo_hooks}:
diff --git a/tests/commands/run_test.py b/tests/commands/run_test.py
index bb233f28..1cec51f2 100644
--- a/tests/commands/run_test.py
+++ b/tests/commands/run_test.py
@@ -416,6 +416,32 @@ def test_multiple_hooks_same_id(cap_out, store, repo_with_passing_hook):
     assert output.count(b'Bash hook') == 2
 
 
+def test_aliased_hook_run(cap_out, store, repo_with_passing_hook):
+    with cwd(repo_with_passing_hook):
+        # Add bash hook on there again, aliased
+        with modify_config() as config:
+            config['repos'][0]['hooks'].append(
+                {'id': 'bash_hook', 'alias': 'foo_bash'},
+            )
+        stage_a_file()
+
+    ret, output = _do_run(
+        cap_out, store, repo_with_passing_hook,
+        run_opts(verbose=True, hook='bash_hook'),
+    )
+    assert ret == 0
+    # Both hooks will run since they share the same ID
+    assert output.count(b'Bash hook') == 2
+
+    ret, output = _do_run(
+        cap_out, store, repo_with_passing_hook,
+        run_opts(verbose=True, hook='foo_bash'),
+    )
+    assert ret == 0
+    # Only the aliased hook runs
+    assert output.count(b'Bash hook') == 1
+
+
 def test_non_ascii_hook_id(repo_with_passing_hook, tempdir_factory):
     with cwd(repo_with_passing_hook):
         _, stdout, _ = cmd_output_mocked_pre_commit_home(