validators: Add check_float validator.

zerver/lib/validator.py

@@ -44,6 +44,12 @@ def check_int(var_name, val):
         return _('%s is not an integer') % (var_name,)
     return None
 
+def check_float(var_name, val):
+    # type: (str, Any) -> Optional[str]
+    if not isinstance(val, float):
+        return _('%s is not a float') % (var_name,)
+    return None
+
 def check_bool(var_name, val):
     # type: (str, Any) -> Optional[str]
     if not isinstance(val, bool):

zerver/tests/test_decorators.py

@@ -30,7 +30,7 @@
     return_success_on_head_request
 )
 from zerver.lib.validator import (
-    check_string, check_dict, check_bool, check_int, check_list, Validator,
+    check_string, check_dict, check_bool, check_float, check_int, check_list, Validator,
     check_variable_type, equals, check_none_or,
 )
 from zerver.models import \
@@ -418,6 +418,17 @@ def test_check_int(self):
         x = [{}]
         self.assertEqual(check_int('x', x), 'x is not an integer')
 
+    def test_check_float(self):
+        # type: () -> None
+        x = 5.5 # type: Any
+        self.assertEqual(check_float('x', x), None)
+
+        x = 5
+        self.assertEqual(check_float('x', x), 'x is not a float')
+
+        x = [{}]
+        self.assertEqual(check_float('x', x), 'x is not a float')
+
     def test_check_list(self):
         # type: () -> None
         x = 999 # type: Any