Add BagStore.has_bag

2 files changed, 17 insertions, 0 deletions

diff --git a/obnamlib/bag_store.py b/obnamlib/bag_store.py
index e95d385d..abe33baf 100644
--- a/obnamlib/bag_store.py
+++ b/obnamlib/bag_store.py
@@ -52,6 +52,14 @@ class BagStore(object):
         serialised = self._fs.cat(filename)
         return deserialise_bag(serialised)
 
+    def has_bag(self, bag_id):
+        filename = self._make_bag_filename(bag_id)
+        try:
+            st = self._fs.lstat(filename)
+        except (IOError, OSError) as e:  # pragma: no cover
+            return False
+        return st.st_size > 0
+
     def get_bag_ids(self):
         for pathname, st in self._fs.scan_tree(self._dirname):
             if self._is_bag_filename(pathname):
diff --git a/obnamlib/bag_store_tests.py b/obnamlib/bag_store_tests.py
index ff9afbe0..ef06fe87 100644
--- a/obnamlib/bag_store_tests.py
+++ b/obnamlib/bag_store_tests.py
@@ -59,6 +59,15 @@ class BagStoreTests(unittest.TestCase):
         store.set_location(self.fs, 'empty')
         self.assertEqual(list(store.get_bag_ids()), [])
 
+    def test_has_a_put_bag(self):
+        self.store.put_bag(self.bag)
+        self.assertTrue(self.store.has_bag(self.bag.get_id()))
+
+    def test_does_not_have_a_removed_bag(self):
+        self.store.put_bag(self.bag)
+        self.store.remove_bag(self.bag.get_id())
+        self.assertFalse(self.store.has_bag(self.bag.get_id()))
+
     def test_lists_bag_that_has_been_put(self):
         self.store.put_bag(self.bag)
         self.assertEqual(list(self.store.get_bag_ids()), [self.bag.get_id()])