[py] handle w3c key case for stacktrace

Signed-off-by: Lucas Tierney <lucast1533@gmail.com>

py/selenium/webdriver/remote/errorhandler.py

@@ -210,10 +210,13 @@ def check_response(self, response):
             screen = value['screen']
 
         stacktrace = None
-        if 'stackTrace' in value and value['stackTrace']:
+        st_value = value.get('stackTrace') or value.get('stacktrace')
+        if st_value:
+            if isinstance(st_value, basestring):
+                st_value = st_value.split('\n')
             stacktrace = []
             try:
-                for frame in value['stackTrace']:
+                for frame in st_value:
                     line = self._value_or_default(frame, 'lineNumber', '')
                     file = self._value_or_default(frame, 'fileName', '<anonymous>')
                     if line:

py/test/unit/selenium/webdriver/remote/test_error_handler.py

@@ -239,3 +239,17 @@ def test_raises_exception_for_unknown_method(handler, code):
 def test_raises_exception_for_method_not_allowed(handler, code):
     with pytest.raises(exceptions.WebDriverException):
         handler.check_response({'status': code, 'value': 'foo'})
+
+
+@pytest.mark.parametrize('key', ['stackTrace', 'stacktrace'])
+def test_relays_exception_stacktrace(handler, key):
+    import json
+    stacktrace = {'lineNumber': 100, 'fileName': 'egg', 'methodName': 'ham', 'className': 'Spam'}
+    value = {key: [stacktrace],
+             'message': 'very bad',
+             'error': ErrorCode.UNKNOWN_METHOD[0]}
+    response = {'status': 400, 'value': json.dumps({'value': value})}
+    with pytest.raises(exceptions.UnknownMethodException) as e:
+        handler.check_response(response)
+
+    assert 'Spam.ham' in e.value.stacktrace[0]