fix: add get_value() convenience function

tests/test_util.py

@@ -41,6 +41,35 @@ class TestGetClassHierarchy(TestCase):
         self.assertEqual(classes, [C, B, A])
 
 
+class TestGetValue(TestCase):
+
+    def test_basic(self):
+
+        class Object:
+            def __init__(self, **kw):
+                self.__dict__.update(kw)
+
+        class Dict(dict):
+            pass
+
+        # dict object
+        obj = {"foo": "bar"}
+        self.assertEqual(mod.get_value(obj, "foo"), "bar")
+
+        # object w/ attrs
+        obj = Object(foo="bar")
+        self.assertEqual(mod.get_value(obj, "foo"), "bar")
+
+        # dict-like w/ attrs
+        obj = Dict({"foo": "bar"})
+        obj.baz = "yyy"
+        self.assertEqual(mod.get_value(obj, "baz"), "yyy")
+
+        # missing attr
+        obj = Object(foo="bar")
+        self.assertRaises(AttributeError, mod.get_value, obj, "baz")
+
+
 class TestLoadEntryPoints(TestCase):
 
     def test_empty(self):