Merge pull request #247 from dkunitsk/master

fix for issue 246

pre_commit/commands/install_uninstall.py

@@ -27,10 +27,14 @@ IDENTIFYING_HASH = '79f09a650522a87b0da915d0d983b2de'
 
 
 def is_our_pre_commit(filename):
+    if not os.path.exists(filename):
+        return False
     return IDENTIFYING_HASH in io.open(filename).read()
 
 
 def is_previous_pre_commit(filename):
+    if not os.path.exists(filename):
+        return False
     contents = io.open(filename).read()
     return any(hash in contents for hash in PREVIOUS_IDENTIFYING_HASHES)
 
@@ -53,7 +57,7 @@ def install(runner, overwrite=False, hooks=False, hook_type='pre-commit'):
 
     # If we have an existing hook, move it to pre-commit.legacy
     if (
-        os.path.exists(hook_path) and
+        os.path.lexists(hook_path) and
         not is_our_pre_commit(hook_path) and
         not is_previous_pre_commit(hook_path)
     ):

testing/util.py

@@ -73,3 +73,8 @@ xfailif_no_pcre_support = pytest.mark.xfail(
     not platform_supports_pcre(),
     reason='grep -P is not supported on this platform',
 )
+
+xfailif_no_symlink = pytest.mark.xfail(
+    not hasattr(os, 'symlink'),
+    reason='Symlink is not supported on this platform',
+)

tests/commands/install_uninstall_test.py

@@ -24,6 +24,7 @@ from pre_commit.util import cwd
 from pre_commit.util import resource_filename
 from testing.fixtures import git_dir
 from testing.fixtures import make_consuming_repo
+from testing.util import xfailif_no_symlink
 
 
 def test_is_not_our_pre_commit():
@@ -88,6 +89,15 @@ def test_install_hooks_directory_not_present(tmpdir_factory):
     assert os.path.exists(runner.pre_commit_path)
 
 
+@xfailif_no_symlink
+def test_install_hooks_dead_symlink(tmpdir_factory):
+    path = git_dir(tmpdir_factory)
+    os.symlink('/fake/baz', os.path.join(path, '.git', 'hooks', 'pre-commit'))
+    runner = Runner(path)
+    install(runner)
+    assert os.path.exists(runner.pre_commit_path)
+
+
 def test_uninstall_does_not_blow_up_when_not_there(tmpdir_factory):
     path = git_dir(tmpdir_factory)
     runner = Runner(path)