Guard agains non boolean values in check_revoked + tests (#128)

* Guard agains non bools in check_revoked + tests

* lint

* whitespace

Author: avishalom

firebase_admin/auth.py

@@ -96,6 +96,10 @@ def verify_id_token(id_token, app=None, check_revoked=False):
           initialized with a credentials.Certificate.
       AuthError: If check_revoked is requested and the token was revoked.
     """
+    if not isinstance(check_revoked, bool):
+        # guard against accidental wrong assignment.
+        raise ValueError('Illegal check_revoked argument. Argument must be of type '
+                         ' bool, but given "{0}".'.format(type(app)))
     token_generator = _get_auth_service(app).token_generator
     verified_claims = token_generator.verify_id_token(id_token)
     if check_revoked:

tests/test_auth.py

@@ -267,6 +267,11 @@ def test_revoked_token_check_revoked(self, user_mgt_app, id_token):
         assert excinfo.value.code == 'ID_TOKEN_REVOKED'
         assert str(excinfo.value) == 'The Firebase ID token has been revoked.'
 
+    @pytest.mark.parametrize('arg', INVALID_BOOLS)
+    def test_invalid_check_revoked(self, arg):
+        with pytest.raises(ValueError):
+            auth.verify_id_token("id_token", check_revoked=arg)
+
     @pytest.mark.parametrize('id_token', valid_tokens.values(), ids=list(valid_tokens))
     def test_revoked_token_do_not_check_revoked(self, user_mgt_app, id_token):
         _instrument_user_manager(user_mgt_app, 200, MOCK_GET_USER_REVOKED_TOKENS_RESPONSE)