Set and get previous generation for a backup run

2 files changed, 17 insertions, 1 deletions

diff --git a/obnam/app.py b/obnam/app.py
index 46527bf1..926ab69c 100644
--- a/obnam/app.py
+++ b/obnam/app.py
@@ -41,6 +41,7 @@ class Application:
         self._exclusion_strings = []
         self._exclusion_regexps = []
         self._filelist = None
+        self._prev_gen = None
         self._store = obnam.Store(self._context)
         
         # When we traverse the file system tree while making a backup,
@@ -180,6 +181,14 @@ class Application:
         
         self._filelist = filelist
 
+    def get_previous_generation(self):
+        """Get the previous generation for a backup run."""
+        return self._prev_gen
+
+    def set_previous_generation(self, gen):
+        """Set the previous generation for a backup run."""
+        self._prev_gen = gen
+
     def find_file_by_name(self, filename):
         """Find a backed up file given its filename.
         
@@ -276,7 +285,7 @@ class Application:
         directory.
 
         """
-
+        
         filenames = self._make_absolute(dirname, filenames)
         filegroups = self.make_filegroups(filenames)
         filegrouprefs = [fg.get_id() for fg in filegroups]
diff --git a/obnam/appTests.py b/obnam/appTests.py
index 0df59534..4019dd92 100644
--- a/obnam/appTests.py
+++ b/obnam/appTests.py
@@ -68,6 +68,13 @@ class ApplicationTests(unittest.TestCase):
         self.app.prune(dirname, dirnames, filenames)
         self.failUnlessEqual(dirnames, ["subdir"])
 
+    def testSetsPreviousGenerationToNoneInitially(self):
+        self.failUnlessEqual(self.app.get_previous_generation(), None)
+
+    def testSetsPreviousGenerationCorrectly(self):
+        self.app.set_previous_generation("pink")
+        self.failUnlessEqual(self.app.get_previous_generation(), "pink")
+
 
 class ApplicationLoadHostBlockTests(unittest.TestCase):