Merge pull request #22 from rconradharris/issue21

Make link idempotent

plypatch/__init__.py

@@ -254,10 +254,21 @@ def abort(self):
 
     def link(self, patch_repo_path):
         """Link a working-repo to a patch-repo."""
+        patch_repo_path = os.path.abspath(os.path.expanduser(patch_repo_path))
+
+        if not os.path.exists(patch_repo_path):
+            raise exc.PathNotFound
+
         if self.patch_repo_path:
-            raise exc.AlreadyLinkedToPatchRepo
+            existing_patch_repo_path = os.path.abspath(
+                    os.path.expanduser(self.patch_repo_path))
 
-        patch_repo_path = os.path.abspath(os.path.expanduser(patch_repo_path))
+            if os.path.samefile(existing_patch_repo_path, patch_repo_path):
+                raise exc.AlreadyLinkedToSamePatchRepo(
+                    patch_repo_path=self.patch_repo_path)
+            else:
+                raise exc.AlreadyLinkedToDifferentPatchRepo(
+                    patch_repo_path=self.patch_repo_path)
 
         self.config('add', config_key='ply.patchrepo',
                     config_value=patch_repo_path)

plypatch/cli.py

@@ -132,8 +132,11 @@ def do(self, args):
         """Link a working-repo to a patch-repo"""
         try:
             self.working_repo.link(args.path)
-        except plypatch.exc.AlreadyLinkedToPatchRepo:
-            die('Already linked to a patch-repo')
+        except plypatch.exc.AlreadyLinkedToSamePatchRepo:
+            print 'Already linked to this patch-repo'
+        except plypatch.exc.AlreadyLinkedToDifferentPatchRepo as e:
+            die('Already linked to a different patch-repo: %s'
+                % e.patch_repo_path)
 
 
 class ResolveCommand(CLICommand):

plypatch/exc.py

@@ -3,6 +3,16 @@ class PlyException(Exception):
 
 
 class AlreadyLinkedToPatchRepo(PlyException):
+    def __init__(self, patch_repo_path=None):
+        super(AlreadyLinkedToPatchRepo, self).__init__()
+        self.patch_repo_path = patch_repo_path
+
+
+class AlreadyLinkedToSamePatchRepo(AlreadyLinkedToPatchRepo):
+    pass
+
+
+class AlreadyLinkedToDifferentPatchRepo(AlreadyLinkedToPatchRepo):
     pass
 
 

tests/functional/test_everything.py

@@ -79,10 +79,14 @@ def assert_based_on(self, expected):
         based_on = re.search('Ply-Based-On: (.*)', commit_msg).group(1)
         self.assertEqual(expected, based_on)
 
-    def test_cant_link_twice(self):
-        with self.assertRaises(plypatch.exc.AlreadyLinkedToPatchRepo):
+    def test_already_linked_same_repo(self):
+        with self.assertRaises(plypatch.exc.AlreadyLinkedToSamePatchRepo):
             self.working_repo.link(self.patch_repo_path)
 
+    def test_already_linked_different_repo(self):
+        with self.assertRaises(plypatch.exc.AlreadyLinkedToDifferentPatchRepo):
+            self.working_repo.link('/bin')
+
     def test_cant_unlink_if_not_linked(self):
         self.working_repo.unlink()
         self.assertIs(None, self.working_repo.patch_repo_path)