Update pagination against requested feedback.

awscli/customizations/paginate.py

@@ -338,16 +338,16 @@ def add_to_parser(self, parser):
         parser.add_argument(self.cli_name, dest=self.py_name,
                             type=self.type_map[self._parse_type])
 
-    def _check_and_warn_negative_max_items(self, value):
+    def _emit_non_positive_max_items_warning(self, value):
         if int(value) <= 0:
             uni_print(
                 "warning: Non-positive values for --max-items may result in undefined behavior.\n",
                 sys.stderr)
 
     def add_to_params(self, parameters, value):
-        if self._serialized_name == 'MaxItems' and value is not None:
-            self._check_and_warn_negative_max_items(value)
         if value is not None:
+            if self._serialized_name == 'MaxItems':
+                self._emit_non_positive_max_items_warning(value)
             pagination_config = parameters.get('PaginationConfig', {})
             pagination_config[self._serialized_name] = value
             parameters['PaginationConfig'] = pagination_config

tests/unit/customizations/test_paginate.py

@@ -10,8 +10,7 @@
 # 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 contextlib
-import io
+import pytest
 
 from awscli.customizations.paginate import PageArgument
 from awscli.testutils import mock, unittest
@@ -355,24 +354,22 @@ def test_can_handle_missing_page_size(self):
         self.assertIsNone(paginate.ensure_paging_params_not_set(
             self.parsed_args, {}))
 
-class TestNonPositiveIntWarnings(TestPaginateBase):
-
-    def setUp(self):
-        super(TestNonPositiveIntWarnings, self).setUp()
-        self._stderr = io.StringIO()
-        self._page_arg = PageArgument('max-items', 'documentation', int, 'MaxItems')
-
-    def test_positive_integer_does_not_raise_warning(self):
-        with contextlib.redirect_stderr(self._stderr):
-            self._page_arg.add_to_params({}, 1)
-            self.assertNotIn('Non-positive values for --max-items are unsupported', self._stderr.getvalue())
-
-    def test_zero_raises_warning(self):
-        with contextlib.redirect_stderr(self._stderr):
-            self._page_arg.add_to_params({}, 0)
-            self.assertIn('Non-positive values for --max-items may result in undefined behavior', self._stderr.getvalue())
-
-    def test_negative_integer_raises_warning(self):
-        with contextlib.redirect_stderr(self._stderr):
-            self._page_arg.add_to_params({}, -1)
-            self.assertIn('Non-positive values for --max-items may result in undefined behavior', self._stderr.getvalue())
+class TestNonPositiveMaxItems:
+    @pytest.fixture
+    def max_items_page_arg(self):
+        return PageArgument('max-items', 'documentation', int, 'MaxItems')
+
+    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