diff --git a/tests/unit/core/test_HashBlob.py b/tests/unit/core/test_HashBlob.py
index d1c282478..93a19ef19 100644
--- a/tests/unit/core/test_HashBlob.py
+++ b/tests/unit/core/test_HashBlob.py
@@ -44,9 +44,15 @@ class BlobFileTest(unittest.TestCase):
         blob_file = BlobFile(self.blob_dir, self.fake_content_hash, self.fake_content_len)
         self.assertTrue(blob_file.verified)
         f = blob_file.open_for_reading()
+        self.assertEqual(1, blob_file.readers)
         c = f.read()
         self.assertEqual(c, self.fake_content)
 
+        # close reader
+        f.close()
+        self.assertEqual(0, blob_file.readers)
+
+
     @defer.inlineCallbacks
     def test_delete(self):
         blob_file = BlobFile(self.blob_dir, self.fake_content_hash, self.fake_content_len)
@@ -58,6 +64,21 @@ class BlobFileTest(unittest.TestCase):
         blob_file = BlobFile(self.blob_dir, self.fake_content_hash)
         self.assertFalse(blob_file.verified)
 
+    @defer.inlineCallbacks
+    def test_delete_fail(self):
+        # deletes should fail if being written to
+        blob_file = BlobFile(self.blob_dir, self.fake_content_hash, self.fake_content_len)
+        writer, finished_d = blob_file.open_for_writing(peer=1)
+        yield self.assertFailure(blob_file.delete(), ValueError)
+        writer.write(self.fake_content)
+        writer.close()
+
+        # deletes should fail if being read and not closed
+        blob_file = BlobFile(self.blob_dir, self.fake_content_hash, self.fake_content_len)
+        self.assertTrue(blob_file.verified)
+        f = blob_file.open_for_reading()
+        yield self.assertFailure(blob_file.delete(), ValueError)
+
     @defer.inlineCallbacks
     def test_too_much_write(self):
         # writing too much data should result in failure