tests: add unit test for propagating TracerProvider

tests/unit/test_client.py

@@ -17,6 +17,20 @@
 import mock
 from google.cloud.spanner_v1 import DirectedReadOptions
 
+hasOtelInstalled = False
+
+try:
+    from opentelemetry.sdk.trace.export import SimpleSpanProcessor
+    from opentelemetry.sdk.trace.export.in_memory_span_exporter import (
+        InMemorySpanExporter,
+    )
+    from opentelemetry.sdk.trace import TracerProvider
+    from opentelemetry.sdk.trace.sampling import ALWAYS_ON
+    from opentelemetry import trace
+    hasOtelInstalled = True
+except ImportError:
+    pass
+
 
 def _make_credentials():
     import google.auth.credentials
@@ -686,3 +700,37 @@ def test_list_instances_w_options(self):
             retry=mock.ANY,
             timeout=mock.ANY,
         )
+
+    def test_observability_options(self):
+        if not hasOtelInstalled:
+            return
+
+        global_tracer_provider = TracerProvider(sampler=ALWAYS_ON)
+        trace.set_tracer_provider(global_tracer_provider)
+        global_trace_exporter = InMemorySpanExporter()
+        global_tracer_provider.add_span_processor(SimpleSpanProcessor(global_trace_exporter))
+
+        inject_tracer_provider = TracerProvider(sampler=ALWAYS_ON)
+        inject_trace_exporter = InMemorySpanExporter()
+        inject_tracer_provider.add_span_processor(SimpleSpanProcessor(inject_trace_exporter))
+        observability_options = dict(tracer_provder=inject_tracer_provider, enable_extended_tracing=True)
+        credentials = _make_credentials()
+        client = self._make_one(project=self.PROJECT, credentials=credentials, observability_options=observability_options)
+
+        instance = client.instance(
+            self.INSTANCE_ID,
+            self.CONFIGURATION_NAME,
+            display_name=self.DISPLAY_NAME,
+            node_count=self.NODE_COUNT,
+            labels=self.LABELS,
+        )
+
+        db = instance.database(self.DATABASE_ID, enable_interceptors_in_tests=True)
+        response = dict()
+        db.execute_sql.return_value = response
+        db.execute_sql('SELECT 1')
+
+        from_global_spans = global_trace_exporter.get_finished_spans()
+        from_inject_spans = inject_trace_exporter.get_finished_spans()
+        self.assertEqual(len(from_global_spans), 0, 'Expecting no spans from the global trace exporter')
+        self.assertEqual(len(from_global_spans) > 0, 'Expecting at least 1 span from the injected trace exporter')