adding tests for experimental off

Author: mhlidd

dd-java-agent/instrumentation/opentelemetry/opentelemetry-1.47/src/test/java/opentelemetry147/metrics/JvmOtlpRuntimeMetricsForkedTest.java

@@ -0,0 +1,107 @@
+package opentelemetry147.metrics;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import datadog.trace.agent.jmxfetch.JvmOtlpRuntimeMetrics;
+import datadog.trace.bootstrap.otel.metrics.data.OtelMetricRegistry;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Set;
+import java.util.TreeSet;
+import java.util.concurrent.TimeUnit;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+// Forked test: runs in an isolated JVM and starts JvmOtlpRuntimeMetrics with the experimental
+// flag OFF, verifying that Development-status instruments are not registered and that the
+// jvm.gc.cause attribute is omitted from jvm.gc.duration data points. The JvmOtlpRuntimeMetrics
+// class uses a one-shot AtomicBoolean to guard registration, so this scenario must run in its
+// own JVM separate from the always-on JvmOtlpRuntimeMetricsTest.
+class JvmOtlpRuntimeMetricsForkedTest {
+
+  @BeforeAll
+  static void setUp() {
+    System.setProperty("dd.metrics.otel.enabled", "true");
+    JvmOtlpRuntimeMetrics.start(false);
+  }
+
+  @Test
+  void registersOnlyStableMetricsWhenExperimentalDisabled() {
+    JvmOtlpRuntimeMetricsTest.MetricCollector collector =
+        new JvmOtlpRuntimeMetricsTest.MetricCollector();
+    OtelMetricRegistry.INSTANCE.collectMetrics(collector);
+
+    Set<String> names = collector.metricNames;
+
+    List<String> expectedStableMetrics =
+        Arrays.asList(
+            "jvm.memory.used",
+            "jvm.memory.committed",
+            "jvm.memory.limit",
+            "jvm.memory.used_after_last_gc",
+            "jvm.thread.count",
+            "jvm.class.loaded",
+            "jvm.class.count",
+            "jvm.class.unloaded",
+            "jvm.cpu.time",
+            "jvm.cpu.count",
+            "jvm.cpu.recent_utilization",
+            "jvm.gc.duration");
+    for (String metric : expectedStableMetrics) {
+      assertTrue(
+          names.contains(metric),
+          "Expected stable metric '" + metric + "' not found. Got: " + new TreeSet<>(names));
+    }
+
+    List<String> developmentMetrics =
+        Arrays.asList(
+            "jvm.memory.init",
+            "jvm.buffer.memory.used",
+            "jvm.buffer.memory.limit",
+            "jvm.buffer.count",
+            "jvm.system.cpu.utilization",
+            "jvm.system.cpu.load_1m",
+            "jvm.file_descriptor.count",
+            "jvm.file_descriptor.limit");
+    for (String metric : developmentMetrics) {
+      assertFalse(
+          names.contains(metric),
+          "Development metric '"
+              + metric
+              + "' should not be registered when experimental disabled. Got: "
+              + new TreeSet<>(names));
+    }
+  }
+
+  @Test
+  void jvmGcDurationDataPointsOmitGcCauseWhenExperimentalDisabled() throws InterruptedException {
+    System.gc();
+
+    List<JvmOtlpRuntimeMetricsTest.DataPointEntry> points = null;
+    long deadlineNanos = System.nanoTime() + TimeUnit.SECONDS.toNanos(2);
+    while (System.nanoTime() < deadlineNanos) {
+      JvmOtlpRuntimeMetricsTest.MetricCollector collector =
+          new JvmOtlpRuntimeMetricsTest.MetricCollector();
+      OtelMetricRegistry.INSTANCE.collectMetrics(collector);
+      points = collector.points.get("jvm.gc.duration");
+      if (points != null && !points.isEmpty()) {
+        break;
+      }
+      Thread.sleep(50);
+    }
+
+    assertNotNull(points, "jvm.gc.duration should have data points after System.gc()");
+    assertFalse(points.isEmpty(), "jvm.gc.duration should have at least one data point");
+    assertTrue(
+        points.stream()
+            .allMatch(
+                p ->
+                    p.attrs.containsKey("jvm.gc.name")
+                        && p.attrs.containsKey("jvm.gc.action")
+                        && !p.attrs.containsKey("jvm.gc.cause")),
+        "jvm.gc.duration data points must carry jvm.gc.name and jvm.gc.action, but not jvm.gc.cause"
+            + " when experimental disabled");
+  }
+}