btrfs: add subvolume_exists

salt/modules/btrfs.py

@@ -675,6 +675,24 @@ def properties(obj, type=None, set=None):
         return ret
 
 
+def subvolume_exists(path):
+    '''
+    Check if a subvolume is present in the filesystem.
+
+    path
+        Mount point for the subvolume (full path)
+
+    CLI Example:
+
+    .. code-block:: bash
+
+        salt '*' btrfs.subvolume_exists /mnt/var
+
+    '''
+    cmd = ['btrfs', 'subvolume', 'show', path]
+    return __salt__['cmd.retcode'](cmd, ignore_retcode=True) == 0
+
+
 def subvolume_create(name, dest=None, qgroupids=None):
     '''
     Create subvolume `name` in `dest`.

tests/unit/modules/test_btrfs.py

@@ -365,6 +365,26 @@ def test_properties_error(self):
         self.assertRaises(CommandExecutionError, btrfs.properties,
                           '/dev/sda1', 'subvol', True)
 
+    def test_subvolume_exists(self):
+        '''
+        Test subvolume_exists
+        '''
+        salt_mock = {
+            'cmd.retcode': MagicMock(return_value=0),
+        }
+        with patch.dict(btrfs.__salt__, salt_mock):
+            assert btrfs.subvolume_exists('/mnt/one')
+
+    def test_subvolume_not_exists(self):
+        '''
+        Test subvolume_exists
+        '''
+        salt_mock = {
+            'cmd.retcode': MagicMock(return_value=1),
+        }
+        with patch.dict(btrfs.__salt__, salt_mock):
+            assert not btrfs.subvolume_exists('/mnt/nowhere')
+
     def test_subvolume_create_fails_parameters(self):
         '''
         Test btrfs subvolume create