morphlib: Add SystemMetadataDir class

This provides access to the /baserock directory as if it were a dict,
abstracting away the details of how to get data out of it.

The abstraction is useful since it is easier to use than accessing
/baserock yourself, and allows the storage format to be changed more
easily.

Keys with / in may be supported in the future. since there have been
discussions about allowing morphologies to be placed in subdirectories.

Adding this support would require creating and removing directory
components when values are set and deleted respectively.

Iterating would require using os.walk instead of glob.iglob, since
python doesn't support ** in globs.

1 files changed, 75 insertions, 0 deletions

diff --git a/morphlib/systemmetadatadir_tests.py b/morphlib/systemmetadatadir_tests.py
new file mode 100644
index 00000000..0126f862
--- /dev/null
+++ b/morphlib/systemmetadatadir_tests.py
@@ -0,0 +1,75 @@
+# Copyright (C) 2013  Codethink Limited
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+#
+# =*= License: GPL-2 =*=
+
+
+import operator
+import os
+import shutil
+import tempfile
+import unittest
+
+import morphlib
+
+
+class SystemMetadataDirTests(unittest.TestCase):
+
+    def setUp(self):
+        self.tempdir = tempfile.mkdtemp()
+        self.metadatadir = os.path.join(self.tempdir, 'baserock')
+        os.mkdir(self.metadatadir)
+        self.smd = morphlib.systemmetadatadir.SystemMetadataDir(
+            self.metadatadir)
+
+    def tearDown(self):
+        shutil.rmtree(self.tempdir)
+
+    def test_add_new(self):
+        self.smd['key'] = {'foo': 'bar'}
+        self.assertEqual(self.smd['key']['foo'], 'bar')
+
+    def test_replace(self):
+        self.smd['key'] = {'foo': 'bar'}
+        self.smd['key'] = {'foo': 'baz'}
+        self.assertEqual(self.smd['key']['foo'], 'baz')
+
+    def test_remove(self):
+        self.smd['key'] = {'foo': 'bar'}
+        del self.smd['key']
+        self.assertTrue('key' not in self.smd)
+
+    def test_iterate(self):
+        self.smd['build-essential'] = "Some data"
+        self.smd['core'] = "More data"
+        self.smd['foundation'] = "Yet more data"
+        self.assertEqual(sorted(self.smd.keys()),
+                         ['build-essential', 'core', 'foundation'])
+        self.assertEqual(dict(self.smd.iteritems()),
+                         {
+                             'build-essential': "Some data",
+                             'core': "More data",
+                             'foundation': "Yet more data",
+                         })
+
+    def test_raises_KeyError(self):
+        self.assertRaises(KeyError, operator.getitem, self.smd, 'key')
+
+    def test_validates_keys(self):
+        for key in ('foo/bar', 'baz\0quux'):
+            self.assertRaises(KeyError, operator.getitem, self.smd, key)
+            self.assertRaises(KeyError, operator.setitem,
+                              self.smd, key, 'value')
+            self.assertRaises(KeyError, operator.delitem, self.smd, key)