[v2] Add warning for non-positive max-items value (#8855)

Emit a warning when a non-positive integer is entered for the max-items pagination parameter.

.changes/next-release/enhancement-paginator-41862.json

@@ -0,0 +1,5 @@
+{
+ "type": "enhancement",
+ "category": "paginator",
+ "description": "Add warning when a non-positive value is provided for the max-items pagination parameter."
+}

awscli/customizations/paginate.py

@@ -24,6 +24,7 @@
 
 """
 import logging
+import sys
 from functools import partial
 
 from botocore import xform_name
@@ -32,7 +33,7 @@
 
 from awscli.arguments import BaseCLIArgument
 from awscli.customizations.exceptions import ParamValidationError
-
+from awscli.customizations.utils import uni_print
 
 logger = logging.getLogger(__name__)
 
@@ -313,6 +314,11 @@ def __init__(self, name, documentation, parse_type, serialized_name):
  self._parse_type = parse_type
  self._required = False
 
+ def _emit_non_positive_max_items_warning(self):
+ uni_print(
+ "warning: Non-positive values for --max-items may result in undefined behavior.\n",
+ sys.stderr)
+
  @property
  def cli_name(self):
  return '--' + self._name
@@ -339,6 +345,8 @@ def add_to_parser(self, parser):
 
  def add_to_params(self, parameters, value):
  if value is not None:
+ if self._serialized_name == 'MaxItems' and int(value) <= 0:
+ self._emit_non_positive_max_items_warning()
  pagination_config = parameters.get('PaginationConfig', {})
  pagination_config[self._serialized_name] = value
  parameters['PaginationConfig'] = pagination_config

tests/unit/customizations/test_paginate.py

@@ -10,6 +10,9 @@
 # distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
 # ANY KIND, either express or implied. See the License for the specific
 # language governing permissions and limitations under the License.
+import pytest
+
+from awscli.customizations.paginate import PageArgument
 from awscli.testutils import mock, unittest
 
 from botocore.exceptions import DataNotFoundError
@@ -20,6 +23,11 @@
 from awscli.customizations.exceptions import ParamValidationError
 
 
+@pytest.fixture
+def max_items_page_arg():
+ return PageArgument('max-items', 'documentation', int, 'MaxItems')
+
+
 class TestPaginateBase(unittest.TestCase):
 
  def setUp(self):
@@ -350,3 +358,19 @@ 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 TestNonPositiveMaxItems:
+ def test_positive_integer_does_not_raise_warning(self, max_items_page_arg, capsys):
+ max_items_page_arg.add_to_params({}, 1)
+ captured = capsys.readouterr()
+ assert captured.err == ""
+
+ def test_zero_raises_warning(self, max_items_page_arg, capsys):
+ max_items_page_arg.add_to_params({}, 0)
+ captured = capsys.readouterr()
+ assert "Non-positive values for --max-items" in captured.err
+
+ def test_negative_integer_raises_warning(self, max_items_page_arg, capsys):
+ max_items_page_arg.add_to_params({}, -1)
+ captured = capsys.readouterr()
+ assert "Non-positive values for --max-items" in captured.err