feat: capture OpenTelemetry logs

This makes sure that if error while uploading are triggered they are
reported at the end of the test session. This makes it easier to debug
issues.

Change-Id: I1dbd3e032e49ed916e2a02102dc68e706ea1cab5

pytest_mergify/__init__.py

@@ -33,6 +33,19 @@ def pytest_terminal_summary(
     ) -> None:
         terminalreporter.section("Mergify CI")
 
+        # Make sure we shutdown and flush traces before existing: this makes
+        # sure that we capture the possible error logs, otherwise they are
+        # emitted on exit (atexit()).
+        if self.mergify_tracer.tracer_provider is not None:
+            self.mergify_tracer.tracer_provider.shutdown()  # type: ignore[no-untyped-call]
+
+        if self.mergify_tracer.log_handler.log_list:
+            terminalreporter.write_line(
+                "There are been some errors reported by the tracer:", red=True
+            )
+            for line in self.mergify_tracer.log_handler.log_list:
+                terminalreporter.write_line(line)
+
         if self.mergify_tracer.token is None:
             terminalreporter.write_line(
                 "No token configured for Mergify; test results will not be uploaded",

pytest_mergify/tracer.py

@@ -1,4 +1,5 @@
 import dataclasses
+import logging
 import os
 
 import opentelemetry.sdk.resources
@@ -32,6 +33,17 @@ def on_start(
             self.trace_id = span.context.trace_id
 
 
+class ListLogHandler(logging.Handler):
+    """Custom logging handler to capture log messages into a list."""
+
+    def __init__(self) -> None:
+        super().__init__()
+        self.log_list: list[str] = []
+
+    def emit(self, record: logging.LogRecord) -> None:
+        self.log_list.append(self.format(record))
+
+
 @dataclasses.dataclass
 class MergifyTracer:
     token: str | None = dataclasses.field(
@@ -51,10 +63,25 @@ class MergifyTracer:
     tracer_provider: opentelemetry.sdk.trace.TracerProvider | None = dataclasses.field(
         init=False, default=None
     )
+    log_handler: ListLogHandler = dataclasses.field(
+        init=False, default_factory=ListLogHandler
+    )
 
     def __post_init__(self) -> None:
         span_processor: SpanProcessor
 
+        # Set up the logger
+        self.log_handler.setLevel(logging.ERROR)  # Capture ERROR logs by default
+        self.log_handler.setFormatter(
+            logging.Formatter("%(asctime)s [%(levelname)s] %(message)s")
+        )
+
+        logger = logging.getLogger("opentelemetry")
+        # FIXME: we should remove the handler when this tracer is not used
+        # (e.g., reconfigure() is called) Since reconfigure() is unlikely to be
+        # called outside our testing things, it's not a big deal to leak it.
+        logger.addHandler(self.log_handler)
+
         if os.environ.get("PYTEST_MERGIFY_DEBUG"):
             self.exporter = export.ConsoleSpanExporter()
             span_processor = export.SimpleSpanProcessor(self.exporter)

tests/test_plugin.py

@@ -84,3 +84,36 @@ def test_foo():
     result = pytester.runpytest_subprocess()
     result.assert_outcomes(passed=1)
     assert "Nothing to do" in result.stdout.lines
+
+
+def test_errors_logs(
+    pytester: _pytest.pytester.Pytester,
+    reconfigure_mergify_tracer: conftest.ReconfigureT,
+) -> None:
+    # This will try to upload traces, but we don't have a real exporter so it will log errors.
+    reconfigure_mergify_tracer(
+        {
+            "MERGIFY_TOKEN": "true",
+            "CI": "1",
+            "GITHUB_ACTIONS": "true",
+            "GITHUB_REPOSITORY": "foo/bar",
+        }
+    )
+    pytester.makepyfile(
+        """
+        import pytest
+
+        from pytest_mergify import utils
+
+        def test_span(pytestconfig):
+            plugin = pytestconfig.pluginmanager.get_plugin("PytestMergify")
+            assert plugin is not None
+            assert plugin.mergify_tracer.exporter is not None
+        """
+    )
+    result = pytester.runpytest_subprocess()
+    result.assert_outcomes(passed=1)
+    assert any(
+        "There are been some errors reported by the tracer:" == line
+        for line in result.stdout.lines
+    )