Implemented Application.get_dir_in_previous_generation.

2 files changed, 31 insertions, 1 deletions

diff --git a/obnam/app.py b/obnam/app.py
index 926ab69c..a832a841 100644
--- a/obnam/app.py
+++ b/obnam/app.py
@@ -276,6 +276,11 @@ class Application:
     def _make_absolute(self, basename, relatives):
         return [os.path.join(basename, name) for name in relatives]
 
+    def get_dir_in_previous_generation(self, dirname):
+        """Return directory in previous generation, or None."""
+        gen = self.get_previous_generation()
+        return self.get_store().lookup_dir(gen, dirname)
+
     def backup_one_dir(self, dirname, subdirs, filenames):
         """Back up non-recursively one directory.
         
diff --git a/obnam/appTests.py b/obnam/appTests.py
index 4019dd92..bce9bddc 100644
--- a/obnam/appTests.py
+++ b/obnam/appTests.py
@@ -243,7 +243,6 @@ class ApplicationUnchangedFileGroupTests(unittest.TestCase):
                                                         stat=self.mock_stat))
 
 
-
 class ApplicationUnchangedDirTests(unittest.TestCase):
 
     def setUp(self):
@@ -394,6 +393,32 @@ class ApplicationFindUnchangedFilegroupsTests(unittest.TestCase):
         self.failUnlessEqual(self.find(self.groups, self.names), [])
 
 
+class ApplicationGetDirInPreviousGenerationTests(unittest.TestCase):
+
+    class MockStore:
+    
+        def __init__(self):
+            self.dict = {
+                "pink": obnam.obj.DirObject(id="id", name="pink"),
+            }
+    
+        def lookup_dir(self, gen, pathname):
+            return self.dict.get(pathname, None)
+
+    def setUp(self):
+        context = obnam.context.Context()
+        self.app = obnam.Application(context)
+        self.app._store = self.MockStore()
+
+    def testReturnsNoneIfDirectoryDidNotExist(self):
+        self.failUnlessEqual(self.app.get_dir_in_previous_generation("xx"),
+                             None)
+
+    def testReturnsDirObjectIfDirectoryDidExist(self):
+        dir = self.app.get_dir_in_previous_generation("pink")
+        self.failUnlessEqual(dir.get_name(), "pink")
+
+
 class ApplicationFindFileByNameTests(unittest.TestCase):
 
     def setUp(self):