test(e2e): report safe OAuth failure locations

.github/e2e-stack/assert_tests_ran.py

@@ -1,4 +1,5 @@
 import os
+import re
 import sys
 import xml.etree.ElementTree as ET
 from pathlib import Path
@@ -45,6 +46,13 @@ def main() -> int:
             if case.get("file") != path or all(case.find(tag) is None for tag in ("failure", "error")):
                 continue
             _ = sys.stdout.write(f"  failed: {case.get('classname', '')}::{case.get('name', '')}\n")
+            for prop in case.findall("./properties/property"):
+                name = prop.get("name", "")
+                value = prop.get("value", "")
+                if name in ("oauth_failure_phase", "oauth_exception_type", "oauth_frame") and re.fullmatch(
+                    r"[A-Za-z0-9_.:<>-]{1,240}", value
+                ):
+                    _ = sys.stdout.write(f"    {name}: {value}\n")
     if (
         selected
         and not missing

tests/code_coverage_tests/test_e2e_changed_gate.py

@@ -226,3 +226,31 @@ def test_an_unusable_secret_is_named_without_printing_its_value(
     assert unprintable not in result.stderr
     assert result.stdout == ""
     assert not env_path.exists()
+
+
+@pytest.mark.parametrize("phase", ("setup", "call", "teardown"))
+def test_oauth_failure_diagnostics_do_not_publish_private_payloads(tmp_path: Path, phase: str) -> None:
+    suite: Final = ET.Element("testsuite")
+    case: Final = ET.SubElement(suite, "testcase", file=SELECTED[0])
+    private: Final = "private-token-in-exception-message"
+    failure: Final = ET.SubElement(case, "failure", message=private)
+    failure.text = private
+    properties: Final = ET.SubElement(case, "properties")
+    for name, value in (
+        ("oauth_failure_phase", phase),
+        ("oauth_exception_type", "AssertionError"),
+        ("oauth_frame", "oauth_gateway.py:120:start"),
+        ("oauth_frame", f"injected\\n{private}"),
+        ("unrelated_property", private),
+    ):
+        _ = ET.SubElement(properties, "property", name=name, value=value)
+    report: Final = tmp_path / "report.xml"
+    ET.ElementTree(suite).write(report)
+    result: Final = subprocess.run(
+        [sys.executable, str(GATE), str(report), SELECTED[0]], capture_output=True, text=True
+    )
+    assert result.returncode == 1
+    assert f"oauth_failure_phase: {phase}" in result.stdout
+    assert "oauth_exception_type: AssertionError" in result.stdout
+    assert "oauth_frame: oauth_gateway.py:120:start" in result.stdout
+    assert private not in result.stdout + result.stderr

tests/e2e/conftest.py

@@ -17,6 +17,7 @@ import functools
 import os
 from collections.abc import Generator, Iterator
 from datetime import datetime, timezone
+from pathlib import Path
 from types import MappingProxyType
 from typing import Final
 
@@ -245,6 +246,13 @@ def pytest_runtest_makereport(
     """Stash the call-phase outcome so teardown can tell a passed test from a
     failed one without re-deriving it."""
     report = yield
+    if item.get_closest_marker("mcp_oauth_live") is not None and call.excinfo is not None:
+        # Publish code locations only, never exception messages, source text or locals.
+        item.user_properties.append(("oauth_failure_phase", report.when))
+        item.user_properties.append(("oauth_exception_type", call.excinfo.type.__name__))
+        for entry in call.excinfo.traceback:
+            item.user_properties.append(("oauth_frame", f"{Path(entry.path).name}:{entry.lineno + 1}:{entry.name}"))
+        report.user_properties = list(item.user_properties)
     if report.when == "call":
         item.stash[_CALL_PASSED] = report.passed
     return report