If Button tag has no type, assume the type of it is 'submit'.

According to <https://developer.mozilla.org/nl/docs/Web/HTML/Element/button>:

+ The type of the button. Possible values are:
    + submit: The button submits the form data to the server.
        + This is the default if the attribute is not specified, or if the attribute is dynamically changed to an empty or invalid value.
    + reset: The button resets all the controls to their initial values.
    + button: The button has no default behavior. It can have client-side scripts associated with the element's events, which are triggered when the events occur.
    + menu: The button opens a popup menu defined via its designated <menu> element.

So, we can treat the button tag with no type specifed as a submit tag.

Thanks Vincent Wagelaar <[email protected]> emailing me about this patch.

robobrowser/forms/form.py

@@ -54,7 +54,7 @@ def _parse_field(tag, tags):
             return fields.Checkbox(checkboxes)
         return fields.Input(tag)
     if tag_type == 'button':
-        tag_type = tag.get('type', '').lower()
+        tag_type = tag.get('type', 'submit').lower()
         if tag_type == 'submit':
             return fields.Submit(tag)
         return fields.Button(tag)