Show a warning for 'on' functions that are not valid event handlers.

Fixes #181

pgzero/actor.py

@@ -148,8 +148,9 @@ def _handle_unexpected_kwargs(self, kwargs):
         if not unexpected_kwargs:
             return
 
-        for found, suggested in spellcheck.compare(
-                unexpected_kwargs, self.EXPECTED_INIT_KWARGS):
+        typos, _ = spellcheck.compare(
+            unexpected_kwargs, self.EXPECTED_INIT_KWARGS)
+        for found, suggested in typos:
             raise TypeError(
                 "Unexpected keyword argument '{}' (did you mean '{}'?)".format(
                     found, suggested))

pgzero/spellcheck.py

@@ -1,3 +1,5 @@
+import re
+
 from operator import itemgetter
 
 from .game import PGZeroGame, positional_parameters
@@ -60,25 +62,32 @@ def compare(have, want):
     This is a greedy algorithm that will take the best answer for each word
     in have in turn.
 
+    Returns (typos with suggestions, unrecognised functions)
     """
     want = set(want)
     have = set(have)
     matched = want & have
     want -= matched
     have -= matched
+    typos = []
     for w in have:
         suggestions = suggest(w, want)
         if suggestions:
             s = suggestions[0]
-            yield w, s
+            typos.append((w, s))
             want.discard(s)
+    have -= set(w for w, s in typos)
+    return typos, have
 
 
 # The list of hooks we support
+
+EVENT_HOOKS = list(PGZeroGame.EVENT_HANDLERS.values())
+
 HOOKS = [
     'draw',
     'update',
-] + list(PGZeroGame.EVENT_HANDLERS.values())
+]
 
 
 # The list of magic module-level constants
@@ -116,6 +125,18 @@ def warn(self, msg, found, suggestion):
             suggestion=suggestion
         ))
 
+    def warn_event_handlers(self, typos, missing):
+        if not typos or missing:
+            return
+        print(
+            "Warning: Found some 'on' functions that are not "
+            "valid event handlers.")
+        for found, suggestion in typos:
+            print("    {found} (did you mean {suggestion}?)".format(
+                found=found, suggestion=suggestion))
+        for f in missing_hooks:
+            print("   ", f)
+
     def error(self, msg, found, suggestion):
         raise InvalidParameter(msg.format(
             found=found,
@@ -138,14 +159,21 @@ def spellcheck(namespace, result=SpellCheckResult()):
         elif isinstance(val, (str, int)):
             consts.append(name)
 
-    for found, suggestion in compare(funcs, HOOKS):
+    typos, _ = compare(funcs, HOOKS)
+    for found, suggestion in typos:
         result.warn(
             "Warning: found function named {found}: "
             "did you mean {suggestion}?",
             found, suggestion
         )
 
-    for found, suggestion in compare(consts, CONSTS):
+    typos, missing = compare(funcs, EVENT_HOOKS)
+    maybe_hook = re.compile("on[A-Z_]")
+    missing_hooks = [f for f in missing if re.match(maybe_hook, f)]
+    result.warn_event_handlers(typos, missing_hooks)
+
+    typos, _ = compare(consts, CONSTS)
+    for found, suggestion in typos:
         result.warn(
             "Warning: found constant named {found}: "
             "did you mean {suggestion}?",

test/test_spellcheck.py

@@ -3,7 +3,7 @@
 
 
 class SuggestionTest(TestCase):
-    HOOKS = spellcheck.HOOKS
+    HOOKS = spellcheck.HOOKS + spellcheck.EVENT_HOOKS
 
     def assert_suggestions(self, w, candidates, expected):
         suggestions = spellcheck.suggest(w, candidates)
@@ -44,19 +44,27 @@ class LoggingSpellCheckResult:
     def __init__(self):
         self.warnings = []
         self.errors = []
+        self.bad_handlers = []
 
     def warn(self, msg, found, suggestion):
         self.warnings.append((found, suggestion))
 
     def error(self, msg, found, suggestion):
         self.errors.append((found, suggestion))
 
+    def warn_event_handlers(self, typos, missing):
+        self.warnings.extend(typos)
+        self.bad_handlers.extend(missing)
+
     def has_error(self, found, suggestion):
         return (found, suggestion) in self.errors
 
     def has_warning(self, found, suggestion):
         return (found, suggestion) in self.warnings
 
+    def has_bad_handler(self, handler):
+        return handler in self.bad_handlers
+
     def get_report(self):
         lines = []
         for type in ('warnings', 'errors'):
@@ -93,6 +101,15 @@ def assert_has_error(self, found, suggestion):
             self.result.get_report()
         )
 
+    def assert_has_handler_warning(self, handler):
+        if self.result.has_bad_handler(handler):
+            return
+
+        raise AssertionError(
+            'Expected warning for hander %s\n' % handler +
+            self.result.get_report()
+        )
+
     def spellcheck(self, namespace):
         spellcheck.spellcheck(namespace, self.result)
 
@@ -125,3 +142,11 @@ def test_misspelled_param(self):
             'on_mouse_down': lambda buton: None,
         })
         self.assert_has_error('buton', 'button')
+
+    def test_invalid_event_handler(self):
+        self.spellcheck({
+            'on_key_press': lambda: None,
+            'onKeyPress': lambda: None
+        })
+        self.assert_has_handler_warning('on_key_press')
+        self.assert_has_handler_warning('onKeyPress')