feat(telemetry): first iteration of in memory Otel tests

tests/integration/telemetry/conftest.py

@@ -0,0 +1,64 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+"""Telemetry test configuration using OpenTelemetry SDK exporters.
+
+This conftest provides in-memory telemetry collection for library_client mode only.
+Tests using these fixtures should skip in server mode since the in-memory collector
+cannot access spans from a separate server process.
+"""
+
+from typing import Any
+
+import opentelemetry.trace as otel_trace
+import pytest
+from opentelemetry import metrics, trace
+from opentelemetry.sdk.metrics import MeterProvider
+from opentelemetry.sdk.metrics.export import InMemoryMetricReader
+from opentelemetry.sdk.trace import ReadableSpan, TracerProvider
+from opentelemetry.sdk.trace.export import SimpleSpanProcessor
+from opentelemetry.sdk.trace.export.in_memory_span_exporter import InMemorySpanExporter
+
+import llama_stack.providers.inline.telemetry.meta_reference.telemetry as telemetry_module
+
+
+class OtelTestCollector:
+    """In-memory collector for OpenTelemetry traces and metrics."""
+
+    def __init__(self):
+        self.span_exporter = InMemorySpanExporter()
+        self.tracer_provider = TracerProvider()
+        self.tracer_provider.add_span_processor(SimpleSpanProcessor(self.span_exporter))
+        trace.set_tracer_provider(self.tracer_provider)
+
+        self.metric_reader = InMemoryMetricReader()
+        self.meter_provider = MeterProvider(metric_readers=[self.metric_reader])
+        metrics.set_meter_provider(self.meter_provider)
+
+    def get_spans(self) -> tuple[ReadableSpan, ...]:
+        return self.span_exporter.get_finished_spans()
+
+    def get_metrics(self) -> Any | None:
+        return self.metric_reader.get_metrics_data()
+
+    def shutdown(self) -> None:
+        self.tracer_provider.shutdown()
+        self.meter_provider.shutdown()
+
+
+@pytest.fixture
+def mock_otlp_collector():
+    """Function-scoped: Fresh telemetry data view for each test."""
+    if hasattr(otel_trace, "_TRACER_PROVIDER_SET_ONCE"):
+        otel_trace._TRACER_PROVIDER_SET_ONCE._done = False  # type: ignore
+
+    collector = OtelTestCollector()
+    telemetry_module._TRACER_PROVIDER = collector.tracer_provider
+
+    yield collector
+
+    telemetry_module._TRACER_PROVIDER = None
+    collector.shutdown()