make dataset.freeze.config compatible with python3

test/Freezefile.yaml

@@ -0,0 +1,32 @@
+common:
+
+  database: "postgresql://user:password@localhost/operational_database"
+  prefix: my_project/dumps/
+  format: json
+  nested:
+
+    property: "inner"
+
+exports:
+
+  - query: "SELECT id, title, date FROM events"
+    filename: "index.json"
+    number: 5
+    bool: true
+    nested:
+
+      property: "override"
+
+  - query: "SELECT id, title, date, country FROM events"
+    filename: "countries/{{country}}.csv"
+    format: csv
+
+  - query: "SELECT * FROM events"
+    filename: "events/{{id}}.json"
+    mode: item
+    wrap: true
+
+  - query: "SELECT * FROM events"
+    filename: "all.json"
+    format: tabson
+

test/test_freeze_config.py

@@ -0,0 +1,35 @@
+import os
+import unittest
+
+from dataset.util import FreezeException
+
+
+class TestConfiguration(unittest.TestCase):
+    def test_init(self):
+        from dataset.freeze.config import Configuration
+
+        self.assertRaises(FreezeException, Configuration, 'x.x')
+        self.assertRaises(FreezeException, Configuration, __file__)
+        cfg = Configuration(os.path.join(os.path.dirname(__file__), 'Freezefile.yaml'))
+
+    def test_exports(self):
+        from dataset.freeze.config import Configuration
+
+        cfg = Configuration(os.path.join(os.path.dirname(__file__), 'Freezefile.yaml'))
+        exports = list(cfg.exports)
+        self.assertEqual(len(exports), 4)
+        self.assertFalse(exports[0].skip)
+        self.assertTrue(exports[0].get_bool('bool'))
+        self.assertEqual(exports[0].get_int('nan', 'default'), 'default')
+        self.assertEqual(exports[0].get_int('number'), 5)
+        self.assert_(exports[0].name)
+    
+    def test_exports_fail(self):
+        from dataset.freeze.config import Configuration
+
+        cfg = Configuration(os.path.join(os.path.dirname(__file__), 'Freezefile.yaml'))
+        cfg.data = None
+        self.assertRaises(FreezeException, list, cfg.exports)
+        cfg.data = {}
+        self.assertRaises(FreezeException, list, cfg.exports)
+