test(showcase): add GAPIC Showcase integration tests for OpenTelemetry T3 tracing

java-showcase/gapic-showcase/src/test/java/com/google/showcase/v1beta1/it/ITOtelT3MetricsExemplar.java

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+/*
+ * Copyright 2026 Google LLC
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google LLC nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package com.google.showcase.v1beta1.it;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.api.client.http.javanet.NetHttpTransport;
+import com.google.api.gax.core.NoCredentialsProvider;
+import com.google.api.gax.tracing.ApiTracerFactory;
+import com.google.api.gax.tracing.CompositeTracerFactory;
+import com.google.api.gax.tracing.OpenTelemetryMetricsFactory;
+import com.google.api.gax.tracing.OpenTelemetryTracingFactory;
+import com.google.showcase.v1beta1.EchoClient;
+import com.google.showcase.v1beta1.EchoRequest;
+import com.google.showcase.v1beta1.EchoSettings;
+import com.google.showcase.v1beta1.stub.EchoStub;
+import com.google.showcase.v1beta1.stub.EchoStubSettings;
+import io.grpc.ManagedChannelBuilder;
+import io.opentelemetry.api.trace.SpanKind;
+import io.opentelemetry.sdk.OpenTelemetrySdk;
+import io.opentelemetry.sdk.metrics.ExemplarFilter;
+import io.opentelemetry.sdk.metrics.SdkMeterProvider;
+import io.opentelemetry.sdk.metrics.data.ExemplarData;
+import io.opentelemetry.sdk.metrics.data.HistogramPointData;
+import io.opentelemetry.sdk.metrics.data.MetricData;
+import io.opentelemetry.sdk.testing.exporter.InMemoryMetricReader;
+import io.opentelemetry.sdk.testing.exporter.InMemorySpanExporter;
+import io.opentelemetry.sdk.trace.SdkTracerProvider;
+import io.opentelemetry.sdk.trace.data.SpanData;
+import io.opentelemetry.sdk.trace.export.SimpleSpanProcessor;
+import java.io.IOException;
+import java.time.Duration;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.List;
+import org.awaitility.Awaitility;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+/** Integration tests for Feature 3 (F3.1–F3.2): T3 Tracing and M3 Metrics Exemplar Correlation. */
+class ITOtelT3MetricsExemplar {
+  private static final String SHOWCASE_SERVER_ADDRESS = "localhost";
+  private static final long SHOWCASE_SERVER_PORT = 7469;
+  private static final String SHOWCASE_GRPC_ENDPOINT =
+      String.format("%s:%s", SHOWCASE_SERVER_ADDRESS, SHOWCASE_SERVER_PORT);
+  private static final String SHOWCASE_HTTPJSON_ENDPOINT =
+      String.format("http://%s:%s", SHOWCASE_SERVER_ADDRESS, SHOWCASE_SERVER_PORT);
+  private static final String SHOWCASE_SERVICE_NAME = "showcase";
+
+  private InMemorySpanExporter spanExporter;
+  private InMemoryMetricReader metricReader;
+  private OpenTelemetrySdk openTelemetrySdk;
+
+  @BeforeEach
+  void setUp() {
+    spanExporter = InMemorySpanExporter.create();
+    metricReader = InMemoryMetricReader.create();
+
+    SdkTracerProvider tracerProvider =
+        SdkTracerProvider.builder()
+            .addSpanProcessor(SimpleSpanProcessor.create(spanExporter))
+            .build();
+
+    SdkMeterProvider meterProvider =
+        SdkMeterProvider.builder()
+            .registerMetricReader(metricReader)
+            .setExemplarFilter(ExemplarFilter.traceBased())
+            .build();
+
+    openTelemetrySdk =
+        OpenTelemetrySdk.builder()
+            .setTracerProvider(tracerProvider)
+            .setMeterProvider(meterProvider)
+            .build();
+  }
+
+  @AfterEach
+  void tearDown() {
+    if (openTelemetrySdk != null) {
+      openTelemetrySdk.close();
+    }
+  }
+
+  // F3.1: HTTP M3 metric records T3 span as exemplar
+  @Test
+  void testHttpJson_m3ExemplarMatchesT3Span() throws Exception {
+    // Verifies that for HTTP/JSON, client request duration metrics attach exemplars
+    // pointing directly to the overall T3 operation span (traceId and spanId match).
+    ApiTracerFactory compositeTracerFactory = createCompositeTracerFactory();
+    EchoSettings settings = createEchoSettings(true);
+    EchoStub stub = createStubWithServiceName(settings, compositeTracerFactory);
+
+    try (EchoClient client = EchoClient.create(stub)) {
+      client.echo(EchoRequest.newBuilder().setContent("exemplar-test-http").build());
+
+      List<SpanData> spans = waitAndCollectSpans(2);
+      SpanData t3Span =
+          spans.stream()
+              .filter(s -> s.getKind() == SpanKind.INTERNAL)
+              .findFirst()
+              .orElseThrow(() -> new AssertionError("T3 INTERNAL span not found in: " + spans));
+
+      Awaitility.await()
+          .atMost(Duration.ofSeconds(5))
+          .untilAsserted(
+              () -> {
+                Collection<MetricData> metrics = metricReader.collectAllMetrics();
+                MetricData durationMetric =
+                    metrics.stream()
+                        .filter(m -> m.getName().equals("gcp.client.request.duration"))
+                        .findFirst()
+                        .orElseThrow(
+                            () -> new AssertionError("Duration metric not found in: " + metrics));
+
+                Collection<HistogramPointData> points =
+                    durationMetric.getHistogramData().getPoints();
+                assertThat(points).hasSize(1);
+                HistogramPointData point = points.iterator().next();
+                List<? extends ExemplarData> exemplars = point.getExemplars();
+                assertThat(exemplars).isNotEmpty();
+
+                ExemplarData exemplar = exemplars.get(0);
+                assertThat(exemplar.getSpanContext().getTraceId()).isEqualTo(t3Span.getTraceId());
+                assertThat(exemplar.getSpanContext().getSpanId()).isEqualTo(t3Span.getSpanId());
+              });
+    }
+  }
+
+  // F3.2: gRPC M3 metric records T3 span as exemplar
+  @Test
+  void testGrpc_m3ExemplarMatchesT3Span() throws Exception {
+    // Verifies that for gRPC, client request duration metrics attach exemplars
+    // pointing directly to the overall T3 operation span (traceId and spanId match).
+    ApiTracerFactory compositeTracerFactory = createCompositeTracerFactory();
+    EchoSettings settings = createEchoSettings(false);
+    EchoStub stub = createStubWithServiceName(settings, compositeTracerFactory);
+
+    try (EchoClient client = EchoClient.create(stub)) {
+      client.echo(EchoRequest.newBuilder().setContent("exemplar-test-grpc").build());
+
+      List<SpanData> spans = waitAndCollectSpans(2);
+      SpanData t3Span =
+          spans.stream()
+              .filter(s -> s.getKind() == SpanKind.INTERNAL)
+              .findFirst()
+              .orElseThrow(() -> new AssertionError("T3 INTERNAL span not found in: " + spans));
+
+      Awaitility.await()
+          .atMost(Duration.ofSeconds(5))
+          .untilAsserted(
+              () -> {
+                Collection<MetricData> metrics = metricReader.collectAllMetrics();
+                MetricData durationMetric =
+                    metrics.stream()
+                        .filter(m -> m.getName().equals("gcp.client.request.duration"))
+                        .findFirst()
+                        .orElseThrow(
+                            () -> new AssertionError("Duration metric not found in: " + metrics));
+
+                Collection<HistogramPointData> points =
+                    durationMetric.getHistogramData().getPoints();
+                assertThat(points).hasSize(1);
+                HistogramPointData point = points.iterator().next();
+                List<? extends ExemplarData> exemplars = point.getExemplars();
+                assertThat(exemplars).isNotEmpty();
+
+                ExemplarData exemplar = exemplars.get(0);
+                assertThat(exemplar.getSpanContext().getTraceId()).isEqualTo(t3Span.getTraceId());
+                assertThat(exemplar.getSpanContext().getSpanId()).isEqualTo(t3Span.getSpanId());
+              });
+    }
+  }
+
+  /**
+   * Creates a composite tracer factory combining both OpenTelemetry tracing and metrics factories.
+   *
+   * @return the configured {@link CompositeTracerFactory}
+   */
+  private CompositeTracerFactory createCompositeTracerFactory() {
+    OpenTelemetryTracingFactory tracingFactory = new OpenTelemetryTracingFactory(openTelemetrySdk);
+    OpenTelemetryMetricsFactory metricsFactory = new OpenTelemetryMetricsFactory(openTelemetrySdk);
+    return new CompositeTracerFactory(Arrays.asList(tracingFactory, metricsFactory));
+  }
+
+  /**
+   * Waits until the in-memory span exporter records at least {@code minSpans} completed spans.
+   *
+   * @param minSpans the minimum number of spans expected
+   * @return the list of completed {@link SpanData} items
+   */
+  private List<SpanData> waitAndCollectSpans(int minSpans) {
+    Awaitility.await()
+        .atMost(Duration.ofSeconds(5))
+        .until(() -> spanExporter.getFinishedSpanItems().size() >= minSpans);
+    return spanExporter.getFinishedSpanItems();
+  }
+
+  /**
+   * Constructs {@link EchoSettings} configured for the local Showcase test server.
+   *
+   * @param isHttpJson {@code true} for HTTP/JSON transport; {@code false} for gRPC transport
+   * @return the configured {@link EchoSettings}
+   * @throws Exception if transport provider initialization fails
+   */
+  private EchoSettings createEchoSettings(boolean isHttpJson) throws Exception {
+    if (isHttpJson) {
+      return EchoSettings.newHttpJsonBuilder()
+          .setCredentialsProvider(NoCredentialsProvider.create())
+          .setTransportChannelProvider(
+              EchoSettings.defaultHttpJsonTransportProviderBuilder()
+                  .setHttpTransport(new NetHttpTransport.Builder().build())
+                  .build())
+          .setEndpoint(SHOWCASE_HTTPJSON_ENDPOINT)
+          .build();
+    } else {
+      return EchoSettings.newBuilder()
+          .setCredentialsProvider(NoCredentialsProvider.create())
+          .setTransportChannelProvider(
+              EchoSettings.defaultGrpcTransportProviderBuilder()
+                  .setChannelConfigurator(ManagedChannelBuilder::usePlaintext)
+                  .build())
+          .setEndpoint(SHOWCASE_GRPC_ENDPOINT)
+          .build();
+    }
+  }
+
+  /**
+   * Instantiates an {@link EchoStub} with custom service name and tracer factory.
+   *
+   * @param settings the client settings to base the stub on
+   * @param tracerFactory the tracer factory to register with the stub
+   * @return the initialized {@link EchoStub}
+   * @throws IOException if stub creation fails
+   */
+  private EchoStub createStubWithServiceName(EchoSettings settings, ApiTracerFactory tracerFactory)
+      throws IOException {
+    EchoStubSettings.Builder builder =
+        (EchoStubSettings.Builder) settings.getStubSettings().toBuilder();
+    builder.setTracerFactory(tracerFactory);
+    return new ExtendedEchoStubSettings(builder).createStub();
+  }
+
+  /** Extended {@link EchoStubSettings} that overrides {@link #getServiceName()} for testing. */
+  private static class ExtendedEchoStubSettings extends EchoStubSettings {
+    /**
+     * Constructs settings wrapping the specified builder.
+     *
+     * @param builder the settings builder
+     * @throws IOException if base settings construction fails
+     */
+    protected ExtendedEchoStubSettings(EchoStubSettings.Builder builder) throws IOException {
+      super(builder);
+    }
+
+    @Override
+    public String getServiceName() {
+      return SHOWCASE_SERVICE_NAME;
+    }
+  }
+}