config: Steal did you mean code from settings.

mopidy/utils/config.py

@@ -33,6 +33,39 @@ def validate_maximum(value, maximum):
         raise ValueError('%r must be smaller than %r.' % (value, maximum))
 
 
+# TODO: move this and levenshtein to a more appropriate class.
+def did_you_mean(name, choices):
+    """Suggest most likely setting based on levenshtein."""
+    if not choices:
+        return None
+
+    name = name.lower()
+    candidates = [(levenshtein(name, c), c) for c in choices]
+    candidates.sort()
+
+    if candidates[0][0] <= 3:
+        return candidates[0][1]
+    return None
+
+
+def levenshtein(a, b):
+    """Calculates the Levenshtein distance between a and b."""
+    n, m = len(a), len(b)
+    if n > m:
+        return levenshtein(b, a)
+
+    current = xrange(n + 1)
+    for i in xrange(1, m + 1):
+        previous, current = current, [i] + [0] * n
+        for j in xrange(1, n + 1):
+            add, delete = previous[j] + 1, current[j - 1] + 1
+            change = previous[j - 1]
+            if a[j - 1] != b[i - 1]:
+                change += 1
+            current[j] = min(add, delete, change)
+    return current[n]
+
+
 class ConfigValue(object):
     """Represents a config key's value and how to handle it.
 
@@ -248,6 +281,9 @@ class ConfigSchema(object):
                 values[key] = self._schema[key].deserialize(value)
             except KeyError:  # not in our schema
                 errors[key] = 'unknown config key.'
+                suggestion = did_you_mean(key, self._schema.keys())
+                if suggestion:
+                    errors[key] += ' Did you mean %s?' % suggestion
             except ValueError as e:  # deserialization failed
                 errors[key] = str(e)
 

tests/utils/config_test.py

@@ -395,3 +395,22 @@ class LogLevelConfigSchemaTest(unittest.TestCase):
         result = schema.format('levels', {'foo.bar': logging.DEBUG, 'baz': logging.INFO})
         self.assertEqual('\n'.join(expected), result)
 
+
+class DidYouMeanTest(unittest.TestCase):
+    def testSuggestoins(self):
+        choices = ('enabled', 'username', 'password', 'bitrate', 'timeout')
+
+        suggestion = config.did_you_mean('bitrate', choices)
+        self.assertEqual(suggestion, 'bitrate')
+
+        suggestion = config.did_you_mean('bitrote', choices)
+        self.assertEqual(suggestion, 'bitrate')
+
+        suggestion = config.did_you_mean('Bitrot', choices)
+        self.assertEqual(suggestion, 'bitrate')
+
+        suggestion = config.did_you_mean('BTROT', choices)
+        self.assertEqual(suggestion, 'bitrate')
+
+        suggestion = config.did_you_mean('btro', choices)
+        self.assertEqual(suggestion, None)

tests/utils/settings_test.py

@@ -149,27 +149,3 @@ class SettingsProxyTest(unittest.TestCase):
     def test_value_ending_in_path_can_be_none(self):
         self.settings.TEST_PATH = None
         self.assertEqual(self.settings.TEST_PATH, None)
-
-
-class DidYouMeanTest(unittest.TestCase):
-    def testSuggestoins(self):
-        defaults = {
-            'MPD_SERVER_HOSTNAME': '::',
-            'MPD_SERVER_PORT': 6600,
-            'SPOTIFY_BITRATE': 160,
-        }
-
-        suggestion = setting_utils.did_you_mean('spotify_bitrate', defaults)
-        self.assertEqual(suggestion, 'SPOTIFY_BITRATE')
-
-        suggestion = setting_utils.did_you_mean('SPOTIFY_BITROTE', defaults)
-        self.assertEqual(suggestion, 'SPOTIFY_BITRATE')
-
-        suggestion = setting_utils.did_you_mean('SPITIFY_BITROT', defaults)
-        self.assertEqual(suggestion, 'SPOTIFY_BITRATE')
-
-        suggestion = setting_utils.did_you_mean('SPTIFY_BITROT', defaults)
-        self.assertEqual(suggestion, 'SPOTIFY_BITRATE')
-
-        suggestion = setting_utils.did_you_mean('SPTIFY_BITRO', defaults)
-        self.assertEqual(suggestion, None)