test added

Author: jackshirazi

dynamic-control/src/test/java/io/opentelemetry/contrib/dynamic/sampler/DelegatingSamplerTest.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.contrib.dynamic.sampler;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.api.trace.SpanKind;
+import io.opentelemetry.context.Context;
+import io.opentelemetry.sdk.trace.samplers.Sampler;
+import io.opentelemetry.sdk.trace.samplers.SamplingDecision;
+import io.opentelemetry.sdk.trace.samplers.SamplingResult;
+import java.util.Collections;
+import org.junit.jupiter.api.Test;
+
+class DelegatingSamplerTest {
+
+  @Test
+  void defaultDelegateIsAlwaysOn() {
+    DelegatingSampler sampler = new DelegatingSampler();
+
+    SamplingDecision decision = doSample(sampler);
+
+    assertThat(decision).isEqualTo(SamplingDecision.RECORD_AND_SAMPLE);
+  }
+
+  @Test
+  void setDelegateNullFallsBackToAlwaysOn() {
+    DelegatingSampler sampler = new DelegatingSampler(Sampler.alwaysOff());
+
+    sampler.setDelegate(null);
+
+    SamplingDecision decision = doSample(sampler);
+    assertThat(decision).isEqualTo(SamplingDecision.RECORD_AND_SAMPLE);
+  }
+
+  @Test
+  void shouldSampleDelegatesToCurrentSamplerAfterUpdate() {
+    DelegatingSampler sampler = new DelegatingSampler(Sampler.alwaysOff());
+
+    assertThat(doSample(sampler)).isEqualTo(SamplingDecision.DROP);
+
+    sampler.setDelegate(Sampler.alwaysOn());
+
+    assertThat(doSample(sampler)).isEqualTo(SamplingDecision.RECORD_AND_SAMPLE);
+  }
+
+  private static SamplingDecision doSample(DelegatingSampler sampler) {
+    SamplingResult result =
+        sampler.shouldSample(
+            Context.root(),
+            "00000000000000000000000000000001",
+            "test-span",
+            SpanKind.INTERNAL,
+            Attributes.empty(),
+            Collections.emptyList());
+    return result.getDecision();
+  }
+}