Merge branch 'sam/gitdir-ref-exists'

Reviewed-By: Adam Coldrick <adam.coldrick@codethink.co.uk>
Reviewed-By: Jim MacArtuhur <jim.macarthur@codethink.co.uk>

2 files changed, 14 insertions, 0 deletions

diff --git a/morphlib/gitdir.py b/morphlib/gitdir.py
index 9fef4f1e..fd7f3808 100644
--- a/morphlib/gitdir.py
+++ b/morphlib/gitdir.py
@@ -537,6 +537,13 @@ class GitDirectory(object):
     def resolve_ref_to_tree(self, ref):
         return self._rev_parse('%s^{tree}' % ref)
 
+    def ref_exists(self, ref):
+        try:
+            self._rev_parse('%s^{commit}' % ref)
+            return True
+        except InvalidRefError:
+            return False
+
     def _list_files_in_work_tree(self):
         for dirpath, subdirs, filenames in os.walk(self.dirname):
             if dirpath == self.dirname and '.git' in subdirs:
diff --git a/morphlib/gitdir_tests.py b/morphlib/gitdir_tests.py
index 456e3716..10b3b7e5 100644
--- a/morphlib/gitdir_tests.py
+++ b/morphlib/gitdir_tests.py
@@ -162,6 +162,13 @@ class GitDirectoryContentsTests(unittest.TestCase):
         self.assertEqual(len(tree), 40)
         self.assertNotEqual(commit, tree)
 
+    def test_ref_exists(self):
+        gd = morphlib.gitdir.GitDirectory(self.dirname)
+        self.assertFalse(gd.ref_exists('non-existant-ref'))
+        self.assertTrue(gd.ref_exists('master'))
+        self.assertFalse(
+            gd.ref_exists('0000000000000000000000000000000000000000'))
+
     def test_store_blob_with_string(self):
         gd = morphlib.gitdir.GitDirectory(self.dirname)
         sha1 = gd.store_blob('test string')