test(o11y): revert OpenTelemetryMetricsFactoryTest to use mocks

Author: blakeli0

sdk-platform-java/gax-java/gax/src/test/java/com/google/api/gax/tracing/OpenTelemetryMetricsFactoryTest.java

@@ -69,16 +69,17 @@ void newTracerWithSpanName_shouldCreateBaseTracer_ifMetricsRecorderIsNull() {
 
   @Test
   void newTracerWithApiTracerContext_shouldMergeApiTracerContext() {
-    LibraryMetadata metadata =
-        LibraryMetadata.newBuilder().setArtifactName("gax-java").setVersion("1.0").build();
-    ApiTracerContext clientLevelTracerContext =
-        ApiTracerContext.newBuilder().setLibraryMetadata(metadata).build();
-    ApiTracerContext methodLevelTracerContext =
-        ApiTracerContext.newBuilder().setLibraryMetadata(LibraryMetadata.empty()).build();
-    
-    ApiTracerFactory factoryWithContext = tracerFactory.withContext(clientLevelTracerContext);
-    ApiTracer actual = factoryWithContext.newTracer(mock(ApiTracer.class), methodLevelTracerContext);
+    ApiTracerContext clientLevelTracerContext = mock(ApiTracerContext.class, RETURNS_DEEP_STUBS);
+    ApiTracerContext methodLevelTracerContext = mock(ApiTracerContext.class);
+    when(clientLevelTracerContext.libraryMetadata().artifactName()).thenReturn("gax-java");
+    when(clientLevelTracerContext.libraryMetadata().isEmpty()).thenReturn(false);
+    when(clientLevelTracerContext.merge(methodLevelTracerContext))
+        .thenReturn(clientLevelTracerContext);
+
+    tracerFactory.withContext(clientLevelTracerContext);
+    ApiTracer actual = tracerFactory.newTracer(mock(ApiTracer.class), methodLevelTracerContext);
 
+    verify(clientLevelTracerContext).merge(methodLevelTracerContext);
     assertThat(actual).isInstanceOf(OpenTelemetryMetricsTracer.class);
   }