Show closest candidates for misspellings of keyword arguments names p…

…ython#824

mypy/messages.py

@@ -573,6 +573,11 @@ def too_many_positional_arguments(self, callee: CallableType,
     def unexpected_keyword_argument(self, callee: CallableType, name: str,
                                     context: Context) -> None:
         msg = 'Unexpected keyword argument "{}"'.format(name) + for_function(callee)
+        # Suggest intended keyword, if any match is found.
+        matches = best_matches(name, list(filter(None, callee.arg_names)))[:3]
+        if matches:
+            suggestion = ";  did you mean {}?".format(pretty_or(matches))
+            msg += "{}".format(suggestion)
         self.fail(msg, context, code=codes.CALL_ARG)
         module = find_defining_module(self.modules, callee)
         if module:

test-data/unit/check-kwargs.test

@@ -86,6 +86,14 @@ def f(a: 'A') -> None: pass # N: "f" defined here
 f(b=object()) # E: Unexpected keyword argument "b" for "f"
 class A: pass
 
+[case testKeywordsMisspelling]
+def f(thing, other): ...
+f(otter='test') # E: Unexpected keyword argument "otter" for "f";  did you mean "other"?
+
+[case testMultipleKeywordsForMisspelling]
+def f(thing, other, atter, btter): ...
+f(otter='test') # E: Unexpected keyword argument "otter" for "f";  did you mean "other", "btter", or "atter"?
+
 [case testKeywordArgumentsWithDynamicallyTypedCallable]
 from typing import Any
 f = None # type: Any