Adding RECAPTCHA_DISABLE to disable recaptcha

docs/config.rst

@@ -37,6 +37,8 @@ Recaptcha
 ``RECAPTCHA_PUBLIC_KEY``    **required** A public key.
 ``RECAPTCHA_PRIVATE_KEY``   **required** A private key.
                             https://www.google.com/recaptcha/admin
+``RECAPTCHA_DISABLE``       Disable recaptcha widgets.
+                            Default is ``False``
 ``RECAPTCHA_PARAMETERS``    **optional** A dict of configuration options.
 ``RECAPTCHA_HTML``          **optional** Override default HTML template
                             for Recaptcha.

docs/form.rst

@@ -142,6 +142,11 @@ Example of RECAPTCHA_PARAMETERS, and RECAPTCHA_DATA_ATTRS::
 For your convenience, when testing your application, if ``app.testing`` is ``True``, the recaptcha
 field will always be valid.
 
+In development environment or when you are offline you can disable all
+recaptcha fields::
+
+    RECAPTCHA_DISABLE = True
+
 And it can be easily setup in the templates:
 
 .. sourcecode:: html+jinja

src/flask_wtf/recaptcha/validators.py

@@ -27,7 +27,7 @@ def __init__(self, message=None):
         self.message = message
 
     def __call__(self, form, field):
-        if current_app.testing:
+        if current_app.testing or current_app.config.get("RECAPTCHA_DISABLE", False):
             return True
 
         if request.json:

src/flask_wtf/recaptcha/widgets.py

@@ -37,6 +37,9 @@ def recaptcha_html(self, public_key):
     def __call__(self, field, error=None, **kwargs):
         """Returns the recaptcha input HTML."""
 
+        if current_app.config.get("RECAPTCHA_DISABLE", False):
+            return Markup("<!-- recaptcha disabled -->")
+
         try:
             public_key = current_app.config["RECAPTCHA_PUBLIC_KEY"]
         except KeyError: