Add validation for numerical pagination argument values to be non-negative

awscli/customizations/paginate.py

@@ -251,11 +251,21 @@ def _get_cli_name(param_objects, token_name):
             return param.cli_name.lstrip('-')
 
 
+# This function checks that the integral value passed to it is non-negative, and raises a
+# ParamValidationError if it not. As such, it can be used as a type for pagination-related
+# argparse arguments that must be non-negative integral values.
+def nonnegative_int(value):
+    ival = int(value)
+    if ival < 0:
+        raise ValueError("invalid literal for nonnegative int() with base 10: '%s'" % value)
+    return ival
+
+
 class PageArgument(BaseCLIArgument):
     type_map = {
         'string': str,
-        'integer': int,
-        'long': int,
+        'integer': nonnegative_int,
+        'long': nonnegative_int,
     }
 
     def __init__(self, name, documentation, parse_type, serialized_name):

tests/unit/customizations/test_paginate.py

@@ -321,3 +321,16 @@ def test_can_handle_missing_page_size(self):
         del self.parsed_args.page_size
         self.assertIsNone(paginate.ensure_paging_params_not_set(
             self.parsed_args, {}))
+
+
+class TestNonnegativeIntType(TestPaginateBase):
+
+    def test_positive_integer_resolves_corectly(self):
+        self.assertEqual(paginate.nonnegative_int(1), 1)
+
+    def test_zero_resolves_corectly(self):
+        self.assertEqual(paginate.nonnegative_int(0), 0)
+
+    def test_negative_integer_raises_error(self):
+        with self.assertRaises(ValueError):
+            paginate.nonnegative_int(-1)