Add mock HTTP response (#22677)

* Add MockHTTPResponse for library-agnostic HTTP response mocking

MockHTTPResponse implements HTTPResponseProtocol without depending on
requests or httpx. It supports the full response API (.json(), .text,
.content, .status_code, .headers, .cookies, .elapsed), streaming via
iter_content() and iter_lines(), raise_for_status() using HTTPStatusError,
and context manager usage.

Demonstrates usage by migrating test_authtoken.py from MockResponse to
MockHTTPResponse — a drop-in replacement with protocol compliance.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* Expand MockHTTPResponse usage to test_openmetrics.py and test_kerberos_unit.py

Also adds three missing API surface members discovered during migration:
- encoding attribute (accessed by openmetrics mixin before iter_lines)
- close() no-op (called by openmetrics mixin after response processing)
- Removes _stream_consumed guard so the same instance can be reused
  across repeated mock.MagicMock(return_value=...) calls

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* Reformat with ddev test --fmt

* Fix headers mutation and add case-insensitive header dict

Two correctness fixes in MockHTTPResponse:

1. When json_data and headers are both provided, the caller's headers dict
   was mutated in-place via setdefault(). Now copies before modifying.

2. self.headers was a plain dict (case-sensitive). HTTP headers are
   case-insensitive per RFC 7230 §3.2. Replace with _CaseInsensitiveDict
   that stores keys lowercased, matching requests.Response behaviour.

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: mwdd146980

datadog_checks_base/changelog.d/22677.added

@@ -0,0 +1 @@
+Add MockHTTPResponse for library-agnostic HTTP response mocking in tests.

datadog_checks_base/datadog_checks/base/utils/http_testing.py

@@ -0,0 +1,155 @@
+# (C) Datadog, Inc. 2026-present
+# All rights reserved
+# Licensed under a 3-clause BSD style license (see LICENSE)
+"""Testing utilities for HTTP client mocking."""
+
+import json
+from io import BytesIO
+from typing import Any, Iterator
+
+__all__ = ['MockHTTPResponse']
+
+
+class _CaseInsensitiveDict(dict):
+    """Case-insensitive dict for HTTP headers per RFC 7230 §3.2.
+
+    Stores keys lowercased so lookup works regardless of the casing used by the
+    caller or by production code (e.g. 'Content-Type' vs 'content-type').
+    """
+
+    def __init__(self, data: dict[str, str] | None = None) -> None:
+        super().__init__()
+        if data:
+            for key, value in data.items():
+                self[key] = value
+
+    def __setitem__(self, key: str, value: str) -> None:
+        super().__setitem__(key.lower(), value)
+
+    def __getitem__(self, key: str) -> str:
+        return super().__getitem__(key.lower())
+
+    def __contains__(self, key: object) -> bool:
+        return super().__contains__(key.lower() if isinstance(key, str) else key)
+
+    def get(self, key: str, default: str | None = None) -> str | None:  # type: ignore[override]
+        return super().get(key.lower(), default)
+
+    def setdefault(self, key: str, default: str = '') -> str:  # type: ignore[override]
+        return super().setdefault(key.lower(), default)
+
+
+class MockHTTPResponse:
+    """Library-agnostic mock HTTP response implementing HTTPResponseProtocol."""
+
+    def __init__(
+        self,
+        content: str | bytes = '',
+        status_code: int = 200,
+        headers: dict[str, str] | None = None,
+        json_data: dict[str, Any] | None = None,
+        file_path: str | None = None,
+        cookies: dict[str, str] | None = None,
+        elapsed_seconds: float = 0.1,
+        normalize_content: bool = True,
+    ):
+        if json_data is not None:
+            content = json.dumps(json_data)
+            # Copy to avoid mutating the caller's dict
+            headers = dict(headers) if headers is not None else {}
+            headers.setdefault('Content-Type', 'application/json')
+        elif file_path is not None:
+            # Open in binary mode to handle both text and binary files correctly
+            # This prevents encoding errors and platform-specific newline translation
+            with open(file_path, 'rb') as f:
+                content = f.read()
+
+        if normalize_content and (
+            (isinstance(content, str) and content.startswith('\n'))
+            or (isinstance(content, bytes) and content.startswith(b'\n'))
+        ):
+            content = content[1:]
+
+        self._content = content.encode('utf-8') if isinstance(content, str) else content
+        self.status_code = status_code
+        self.headers = _CaseInsensitiveDict(headers or {})
+        self.cookies = cookies or {}
+        self.encoding: str | None = None
+
+        from datetime import timedelta
+
+        self.elapsed = timedelta(seconds=elapsed_seconds)
+        self._stream = BytesIO(self._content)
+
+        def mock_getpeercert(_self, binary_form=False):
+            return b'mock-cert' if binary_form else {}
+
+        self.raw = type(
+            'MockRaw',
+            (),
+            {
+                'connection': type(
+                    'MockConnection', (), {'sock': type('MockSocket', (), {'getpeercert': mock_getpeercert})()}
+                )()
+            },
+        )()
+
+    @property
+    def content(self) -> bytes:
+        return self._content
+
+    @property
+    def text(self) -> str:
+        return self._content.decode('utf-8')
+
+    def json(self, **kwargs: Any) -> Any:
+        return json.loads(self.text, **kwargs)
+
+    def raise_for_status(self) -> None:
+        if self.status_code >= 400:
+            from datadog_checks.base.utils.http_exceptions import HTTPStatusError
+
+            message = (
+                f'{self.status_code} Client Error' if self.status_code < 500 else f'{self.status_code} Server Error'
+            )
+            raise HTTPStatusError(message, response=self)
+
+    def iter_content(self, chunk_size: int | None = None, decode_unicode: bool = False) -> Iterator[bytes | str]:
+        # chunk_size=None means return the entire content as a single chunk (matches requests behavior)
+        chunk_size = chunk_size if chunk_size is not None else len(self._content) or 1
+        self._stream.seek(0)
+        while chunk := self._stream.read(chunk_size):
+            # Decode to string when decode_unicode=True (matches requests behavior)
+            yield chunk.decode('utf-8') if decode_unicode else chunk
+
+    def iter_lines(
+        self, chunk_size: int | None = None, decode_unicode: bool = False, delimiter: bytes | str | None = None
+    ) -> Iterator[bytes | str]:
+        # Handle string delimiter by converting to bytes
+        if isinstance(delimiter, str):
+            delimiter = delimiter.encode('utf-8')
+        delimiter = delimiter or b'\n'
+
+        self._stream.seek(0)
+        lines = self._stream.read().split(delimiter)
+        # bytes.split() produces a trailing empty element when content ends with the
+        # delimiter (e.g. b'a\nb\n'.split(b'\n') == [b'a', b'b', b'']). requests uses
+        # splitlines() for the default case which does not have this behavior, so we
+        # strip the trailing empty element to match.
+        if lines and not lines[-1]:
+            lines.pop()
+        for line in lines:
+            # Decode to string when decode_unicode=True (matches requests behavior)
+            yield line.decode('utf-8') if decode_unicode else line
+
+    def close(self) -> None:
+        # No-op: requests.Response.close() releases the network connection, but
+        # content is already buffered in memory. Matching that behaviour here
+        # so the same instance can be returned by a mock multiple times.
+        pass
+
+    def __enter__(self) -> 'MockHTTPResponse':
+        return self
+
+    def __exit__(self, exc_type: Any, exc_val: Any, exc_tb: Any) -> bool | None:
+        return None

datadog_checks_base/tests/base/checks/openmetrics/test_legacy/test_openmetrics.py

@@ -19,9 +19,9 @@
 from prometheus_client.samples import Sample
 
 from datadog_checks.base import ensure_bytes
+from datadog_checks.base.utils.http_testing import MockHTTPResponse
 from datadog_checks.checks.openmetrics import OpenMetricsBaseCheck
 from datadog_checks.dev import get_here
-from datadog_checks.dev.http import MockResponse
 
 text_content_type = 'text/plain; version=0.0.4'
 FIXTURE_PATH = os.path.abspath(os.path.join(get_here(), '..', '..', '..', '..', 'fixtures', 'prometheus'))
@@ -113,7 +113,7 @@ def test_config_instance(mocked_prometheus_check):
 
 def test_process(text_data, mocked_prometheus_check, mocked_prometheus_scraper_config, ref_gauge):
     check = mocked_prometheus_check
-    check.poll = mock.MagicMock(return_value=MockResponse(text_data, headers={'Content-Type': text_content_type}))
+    check.poll = mock.MagicMock(return_value=MockHTTPResponse(text_data, headers={'Content-Type': text_content_type}))
     check.process_metric = mock.MagicMock()
     check.process(mocked_prometheus_scraper_config)
     check.poll.assert_called_with(mocked_prometheus_scraper_config)
@@ -734,7 +734,7 @@ def test_filter_sample_on_gauge(p_check, mocked_prometheus_scraper_config):
     expected_metric.add_metric(['heapster-v1.4.3'], 1)
 
     # Iter on the generator to get all metrics
-    response = MockResponse(text_data, headers={'Content-Type': text_content_type})
+    response = MockHTTPResponse(text_data, headers={'Content-Type': text_content_type})
     check = p_check
     mocked_prometheus_scraper_config['_text_filter_blacklist'] = ["deployment=\"kube-dns\""]
     metrics = list(check.parse_metric_family(response, mocked_prometheus_scraper_config))
@@ -767,7 +767,7 @@ def test_parse_one_gauge(p_check, mocked_prometheus_scraper_config):
     expected_etcd_metric.add_metric([], 1)
 
     # Iter on the generator to get all metrics
-    response = MockResponse(text_data, headers={'Content-Type': text_content_type})
+    response = MockHTTPResponse(text_data, headers={'Content-Type': text_content_type})
     check = p_check
     metrics = list(check.parse_metric_family(response, mocked_prometheus_scraper_config))
 
@@ -799,7 +799,7 @@ def test_parse_one_counter(p_check, mocked_prometheus_scraper_config):
     expected_etcd_metric.name = 'go_memstats_mallocs_total'
 
     # Iter on the generator to get all metrics
-    response = MockResponse(text_data, headers={'Content-Type': text_content_type})
+    response = MockHTTPResponse(text_data, headers={'Content-Type': text_content_type})
     check = p_check
     metrics = list(check.parse_metric_family(response, mocked_prometheus_scraper_config))
 
@@ -857,7 +857,7 @@ def test_parse_one_histograms_with_label(p_check, mocked_prometheus_scraper_conf
     )
 
     # Iter on the generator to get all metrics
-    response = MockResponse(text_data, headers={'Content-Type': text_content_type})
+    response = MockHTTPResponse(text_data, headers={'Content-Type': text_content_type})
     check = p_check
     metrics = list(check.parse_metric_family(response, mocked_prometheus_scraper_config))
 
@@ -991,7 +991,7 @@ def test_parse_one_histogram(p_check, mocked_prometheus_scraper_config):
     )
 
     # Iter on the generator to get all metrics
-    response = MockResponse(text_data, headers={'Content-Type': text_content_type})
+    response = MockHTTPResponse(text_data, headers={'Content-Type': text_content_type})
     check = p_check
     metrics = list(check.parse_metric_family(response, mocked_prometheus_scraper_config))
     assert 1 == len(metrics)
@@ -1093,7 +1093,7 @@ def test_parse_two_histograms_with_label(p_check, mocked_prometheus_scraper_conf
     )
 
     # Iter on the generator to get all metrics
-    response = MockResponse(text_data, headers={'Content-Type': text_content_type})
+    response = MockHTTPResponse(text_data, headers={'Content-Type': text_content_type})
     check = p_check
     metrics = list(check.parse_metric_family(response, mocked_prometheus_scraper_config))
 
@@ -1131,7 +1131,7 @@ def test_decumulate_histogram_buckets(p_check, mocked_prometheus_scraper_config)
         'rest_client_request_latency_seconds_count{url="http://127.0.0.1:8080/api",verb="GET"} 755\n'
     )
 
-    response = MockResponse(text_data, headers={'Content-Type': text_content_type})
+    response = MockHTTPResponse(text_data, headers={'Content-Type': text_content_type})
     check = p_check
     metrics = list(check.parse_metric_family(response, mocked_prometheus_scraper_config))
 
@@ -1220,7 +1220,7 @@ def test_decumulate_histogram_buckets_single_bucket(p_check, mocked_prometheus_s
         'rest_client_request_latency_seconds_count{url="http://127.0.0.1:8080/api",verb="GET"} 755\n'
     )
 
-    response = MockResponse(text_data, headers={'Content-Type': text_content_type})
+    response = MockHTTPResponse(text_data, headers={'Content-Type': text_content_type})
     check = p_check
     metrics = list(check.parse_metric_family(response, mocked_prometheus_scraper_config))
 
@@ -1283,7 +1283,7 @@ def test_decumulate_histogram_buckets_multiple_contexts(p_check, mocked_promethe
         'rest_client_request_latency_seconds_count{url="http://127.0.0.1:8080/api",verb="POST"} 150\n'
     )
 
-    response = MockResponse(text_data, headers={'Content-Type': text_content_type})
+    response = MockHTTPResponse(text_data, headers={'Content-Type': text_content_type})
     check = p_check
     metrics = list(check.parse_metric_family(response, mocked_prometheus_scraper_config))
 
@@ -1351,7 +1351,7 @@ def test_decumulate_histogram_buckets_negative_buckets(p_check, mocked_prometheu
         'random_histogram_count{url="http://127.0.0.1:8080/api",verb="GET"} 70\n'
     )
 
-    response = MockResponse(text_data, headers={'Content-Type': text_content_type})
+    response = MockHTTPResponse(text_data, headers={'Content-Type': text_content_type})
     check = p_check
     metrics = list(check.parse_metric_family(response, mocked_prometheus_scraper_config))
 
@@ -1403,7 +1403,7 @@ def test_decumulate_histogram_buckets_no_buckets(p_check, mocked_prometheus_scra
         'rest_client_request_latency_seconds_count{url="http://127.0.0.1:8080/api",verb="GET"} 755\n'
     )
 
-    response = MockResponse(text_data, headers={'Content-Type': text_content_type})
+    response = MockHTTPResponse(text_data, headers={'Content-Type': text_content_type})
     check = p_check
     metrics = list(check.parse_metric_family(response, mocked_prometheus_scraper_config))
 
@@ -1474,7 +1474,7 @@ def test_parse_one_summary(p_check, mocked_prometheus_scraper_config):
     expected_etcd_metric.add_sample("http_response_size_bytes", {"handler": "prometheus", "quantile": "0.99"}, 25763.0)
 
     # Iter on the generator to get all metrics
-    response = MockResponse(text_data, headers={'Content-Type': text_content_type})
+    response = MockHTTPResponse(text_data, headers={'Content-Type': text_content_type})
     check = p_check
     metrics = list(check.parse_metric_family(response, mocked_prometheus_scraper_config))
 
@@ -1517,7 +1517,7 @@ def test_parse_one_summary_with_no_quantile(p_check, mocked_prometheus_scraper_c
     expected_etcd_metric.add_metric(["prometheus"], 5.0, 120512.0)
 
     # Iter on the generator to get all metrics
-    response = MockResponse(text_data, headers={'Content-Type': text_content_type})
+    response = MockHTTPResponse(text_data, headers={'Content-Type': text_content_type})
     check = p_check
     metrics = list(check.parse_metric_family(response, mocked_prometheus_scraper_config))
 
@@ -1572,7 +1572,7 @@ def test_parse_two_summaries_with_labels(p_check, mocked_prometheus_scraper_conf
     )
 
     # Iter on the generator to get all metrics
-    response = MockResponse(text_data, headers={'Content-Type': text_content_type})
+    response = MockHTTPResponse(text_data, headers={'Content-Type': text_content_type})
     check = p_check
     metrics = list(check.parse_metric_family(response, mocked_prometheus_scraper_config))
 
@@ -1613,7 +1613,7 @@ def test_parse_one_summary_with_none_values(p_check, mocked_prometheus_scraper_c
     )
 
     # Iter on the generator to get all metrics
-    response = MockResponse(text_data, headers={'Content-Type': text_content_type})
+    response = MockHTTPResponse(text_data, headers={'Content-Type': text_content_type})
     check = p_check
     metrics = list(check.parse_metric_family(response, mocked_prometheus_scraper_config))
     assert 1 == len(metrics)
@@ -2634,7 +2634,7 @@ def test_filter_metrics(
 def test_metadata_default(mocked_openmetrics_check_factory, text_data, datadog_agent):
     instance = dict(OPENMETRICS_CHECK_INSTANCE)
     check = mocked_openmetrics_check_factory(instance)
-    check.poll = mock.MagicMock(return_value=MockResponse(text_data, headers={'Content-Type': text_content_type}))
+    check.poll = mock.MagicMock(return_value=MockHTTPResponse(text_data, headers={'Content-Type': text_content_type}))
 
     check.check(instance)
     datadog_agent.assert_metadata_count(0)
@@ -2645,7 +2645,7 @@ def test_metadata_transformer(mocked_openmetrics_check_factory, text_data, datad
     instance['metadata_metric_name'] = 'kubernetes_build_info'
     instance['metadata_label_map'] = {'version': 'gitVersion'}
     check = mocked_openmetrics_check_factory(instance)
-    check.poll = mock.MagicMock(return_value=MockResponse(text_data, headers={'Content-Type': text_content_type}))
+    check.poll = mock.MagicMock(return_value=MockHTTPResponse(text_data, headers={'Content-Type': text_content_type}))
 
     version_metadata = {
         'version.major': '1',
@@ -2672,7 +2672,10 @@ def test_ssl_verify_not_raise_warning(caplog, mocked_openmetrics_check_factory,
     check = mocked_openmetrics_check_factory(instance)
     scraper_config = check.get_scraper_config(instance)
 
-    with caplog.at_level(logging.DEBUG), mock.patch('requests.Session.get', return_value=MockResponse('httpbin.org')):
+    with (
+        caplog.at_level(logging.DEBUG),
+        mock.patch('requests.Session.get', return_value=MockHTTPResponse('httpbin.org')),
+    ):
         resp = check.send_request('https://httpbin.org/get', scraper_config)
 
     assert "httpbin.org" in resp.content.decode('utf-8')
@@ -2696,7 +2699,10 @@ def test_send_request_with_dynamic_prometheus_url(caplog, mocked_openmetrics_che
     # `prometheus_url` changed just before calling `send_request`
     scraper_config['prometheus_url'] = 'https://www.example.com/foo/bar'
 
-    with caplog.at_level(logging.DEBUG), mock.patch('requests.Session.get', return_value=MockResponse('httpbin.org')):
+    with (
+        caplog.at_level(logging.DEBUG),
+        mock.patch('requests.Session.get', return_value=MockHTTPResponse('httpbin.org')),
+    ):
         resp = check.send_request('https://httpbin.org/get', scraper_config)
 
     assert "httpbin.org" in resp.content.decode('utf-8')
@@ -2736,7 +2742,7 @@ def test_simple_type_overrides(aggregator, mocked_prometheus_check, text_data):
     config = check.get_scraper_config(instance)
     config['_dry_run'] = False
 
-    check.poll = mock.MagicMock(return_value=MockResponse(text_data, headers={'Content-Type': text_content_type}))
+    check.poll = mock.MagicMock(return_value=MockHTTPResponse(text_data, headers={'Content-Type': text_content_type}))
     check.process(config)
 
     aggregator.assert_metric('prometheus.process.vm.bytes', count=1, metric_type=aggregator.MONOTONIC_COUNT)
@@ -2759,7 +2765,7 @@ def test_wildcard_type_overrides(aggregator, mocked_prometheus_check, text_data)
     config = check.get_scraper_config(instance)
     config['_dry_run'] = False
 
-    check.poll = mock.MagicMock(return_value=MockResponse(text_data, headers={'Content-Type': text_content_type}))
+    check.poll = mock.MagicMock(return_value=MockHTTPResponse(text_data, headers={'Content-Type': text_content_type}))
     check.process(config)
 
     aggregator.assert_metric('prometheus.process.vm.bytes', count=1, metric_type=aggregator.MONOTONIC_COUNT)
@@ -2942,7 +2948,7 @@ def test_use_process_start_time(
 
     check = mocked_openmetrics_check_factory(instance)
     test_data = _make_test_use_process_start_time_data(process_start_time)
-    check.poll = mock.MagicMock(return_value=MockResponse(test_data, headers={'Content-Type': text_content_type}))
+    check.poll = mock.MagicMock(return_value=MockHTTPResponse(test_data, headers={'Content-Type': text_content_type}))
 
     for _ in range(0, 5):
         aggregator.reset()
@@ -2995,7 +3001,9 @@ def test_refresh_bearer_token(text_data, mocked_openmetrics_check_factory):
 
     with patch.object(OpenMetricsBaseCheck, 'KUBERNETES_TOKEN_PATH', os.path.join(TOKENS_PATH, 'default_token')):
         check = mocked_openmetrics_check_factory(instance)
-        check.poll = mock.MagicMock(return_value=MockResponse(text_data, headers={'Content-Type': text_content_type}))
+        check.poll = mock.MagicMock(
+            return_value=MockHTTPResponse(text_data, headers={'Content-Type': text_content_type})
+        )
         instance = check.get_scraper_config(instance)
         assert instance['_bearer_token'] == 'my default token'
         time.sleep(1.5)