Merge pull request #34 from moggers87/23-config-better-errors

Better errors from config objects

CHANGELOG.rst

@@ -2,8 +2,10 @@ Unreleased
 ----------
 
 - Added vesrioneer
-- Fix bug where `exhibit serve` was not serving files with extension stripping
-  enabled
+- Fix bug where ``exhibit serve`` was not serving files with extension
+  stripping enabled
+- ``KeyError``s raised by ``Config`` now display the path of the node they are
+  attached to, making debuging missing keys far easier.
 
 .. _zero-zero-three:
 

exhibition/main.py

@@ -48,15 +48,23 @@ class Config:
     If a key cannot be found in this instance, the parent :class:`Config` will
     be searched (and its parent, etc.)
     """
-    def __init__(self, data=None, parent=None):
+    def __init__(self, data=None, parent=None, node=None):
         """
         :param data:
             Can be one of a string, a file-like object, a dict-like object, or
             ``None``. The first two will be assumed as YAML
         :param parent:
-            Parent :class:`Config` or ``None`` if this is the root configuration object
+            Parent :class:`Config` or ``None`` if this is the root
+            configuration object
+        :param node:
+            The node that this object to bound to, or ``None`` if it is the
+            root configuration object
         """
+        assert (parent is None) == (node is None), \
+            "Either both parent and node are defined or they are both None"
+
         self.parent = parent
+        self.node = node
         self._base_config = {}
 
         if data:
@@ -88,14 +96,24 @@ def from_path(cls, path):
 
         return obj
 
+    def get_name(self):
+        if self.node is None:
+            return SITE_YAML_PATH
+        else:
+            return self.node.full_path
+
     def __getitem__(self, key):
         try:
             return self._base_config[key]
-        except KeyError:
+        except KeyError as exp:
+            exp_str = "Could not find %s in %s" % (key, self.get_name())
             if self.parent is None:
-                raise
+                raise KeyError(exp_str) from exp
             else:
-                return self.parent[key]
+                try:
+                    return self.parent[key]
+                except KeyError as exp_parent:
+                    raise KeyError(exp_str) from exp
 
     def __setitem__(self, key, value):
         self._base_config[key] = value
@@ -143,7 +161,9 @@ def copy(self):
         return klass(self._base_config.copy(), self.parent)
 
     def __repr__(self):
-        return "<%s: %s>" % (self.__class__.__name__, self._base_config.keys())
+        return "<%s: %s: %s>" % (self.__class__.__name__,
+                                 self.get_name(),
+                                 self._base_config.keys())
 
 
 class Node:
@@ -180,7 +200,7 @@ def __init__(self, path, parent, meta=None):
 
         self.is_leaf = self.path_obj.is_file()
 
-        self._meta = Config({}, getattr(self.parent, "meta", None))
+        self._meta = Config({}, parent=getattr(self.parent, "meta", None), node=self.parent)
         if meta:
             self._meta.update(meta)
 

exhibition/tests/test_config.py

@@ -21,11 +21,11 @@
 
 from io import StringIO
 from tempfile import NamedTemporaryFile
-from unittest import TestCase
+from unittest import TestCase, mock
 
 from ruamel.yaml import YAML
 
-from exhibition.main import Config
+from exhibition.main import Config, SITE_YAML_PATH
 
 
 YAML_DATA = """
@@ -90,7 +90,7 @@ def test_getitem(self):
 
     def test_getitem_with_parent(self):
         parent = Config({"test": True})
-        settings = Config(YAML_DATA, parent=parent)
+        settings = Config(YAML_DATA, parent=parent, node=mock.Mock())
 
         self.assertEqual(settings["sitename"], "bob")
         self.assertEqual(settings["thingy"], ["one", "two", "three"])
@@ -111,7 +111,7 @@ def test_keys(self):
 
     def test_keys_with_parent(self):
         parent = Config({"test": True})
-        settings = Config(YAML_DATA, parent=parent)
+        settings = Config(YAML_DATA, parent=parent, node=mock.Mock())
 
         self.assertCountEqual(list(settings.keys()), ["sitename", "thingy", "test"])
         self.assertCountEqual(list(parent.keys()), ["test"])
@@ -123,7 +123,7 @@ def test_values(self):
 
     def test_values_with_parent(self):
         parent = Config({"test": True})
-        settings = Config(YAML_DATA, parent=parent)
+        settings = Config(YAML_DATA, parent=parent, node=mock.Mock())
 
         self.assertCountEqual(list(settings.values()), ["bob", ["one", "two", "three"], True])
         self.assertCountEqual(list(parent.values()), [True])
@@ -136,7 +136,7 @@ def test_items(self):
 
     def test_items_with_parent(self):
         parent = Config({"test": True})
-        settings = Config(YAML_DATA, parent=parent)
+        settings = Config(YAML_DATA, parent=parent, node=mock.Mock())
 
         self.assertCountEqual(list(settings.items()),
                               [("sitename", "bob"), ("thingy", ["one", "two", "three"]),
@@ -152,7 +152,7 @@ def test_contains(self):
 
     def test_contains_with_parent(self):
         parent = Config({"test": True})
-        settings = Config(YAML_DATA, parent=parent)
+        settings = Config(YAML_DATA, parent=parent, node=mock.Mock())
 
         self.assertIn("test", settings)
         self.assertIn("sitename", settings)
@@ -169,7 +169,46 @@ def test_len(self):
 
     def test_len_with_parent(self):
         parent = Config({"test": True})
-        settings = Config(YAML_DATA, parent=parent)
+        settings = Config(YAML_DATA, parent=parent, node=mock.Mock())
 
         self.assertEqual(len(settings), 3)
         self.assertEqual(len(parent), 1)
+
+    def test_parent_and_node(self):
+        with self.assertRaises(AssertionError):
+            Config({}, parent=Config({}))
+
+        with self.assertRaises(AssertionError):
+            Config({}, node=mock.Mock())
+
+        # these should be fine
+        Config({})
+        Config({}, parent=Config({}), node=mock.Mock())
+
+    def test_get_name_for_root_config(self):
+        config = Config({})
+        self.assertEqual(config.get_name(), SITE_YAML_PATH)
+
+    def test_get_name_for_node_config(self):
+        node = mock.Mock()
+        node.full_path = "this-file.html"
+        config = Config({}, parent=mock.Mock(), node=node)
+        self.assertEqual(config.get_name(), node.full_path)
+
+    def test_KeyError_contains_name_of_child(self):
+        node = mock.Mock()
+        node.full_path = "this-file.html"
+        config = Config({}, parent=Config({}), node=node)
+
+        with self.assertRaises(KeyError) as exp:
+            config["some key"]
+
+        self.assertIn("this-file.html", str(exp.exception))
+
+    def test_KeyError_contains_name_of_site_yaml(self):
+        config = Config({})
+
+        with self.assertRaises(KeyError) as exp:
+            config["some key"]
+
+        self.assertIn(SITE_YAML_PATH, str(exp.exception))