Introduce OtlpWriterTest.java

Author: mtoffl01

dd-trace-core/src/test/java/datadog/trace/common/writer/OtlpWriterTest.java

@@ -0,0 +1,63 @@
+package datadog.trace.common.writer;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.mockito.Mockito.verify;
+
+import datadog.trace.api.config.OtlpConfig;
+import datadog.trace.core.otlp.common.OtlpSender;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+@ExtendWith(MockitoExtension.class)
+class OtlpWriterTest {
+
+  @Mock OtlpSender sender;
+
+  @Test
+  void closeShutsDownSender() {
+    OtlpWriter writer = OtlpWriter.builder().sender(sender).build();
+    writer.start();
+
+    writer.close();
+
+    verify(sender).shutdown();
+  }
+
+  @Test
+  void getApisIsEmpty() {
+    OtlpWriter writer = OtlpWriter.builder().sender(sender).build();
+    writer.start();
+    try {
+      assertTrue(writer.getApis().isEmpty());
+    } finally {
+      writer.close();
+    }
+  }
+
+  @Test
+  void builderRespectsInjectedSenderAcrossProtocols() {
+    for (OtlpConfig.Protocol protocol : OtlpConfig.Protocol.values()) {
+      OtlpWriter writer = OtlpWriter.builder().protocol(protocol).sender(sender).build();
+      writer.start();
+      writer.close();
+    }
+    // One shutdown per writer we built.
+    verify(sender, org.mockito.Mockito.times(OtlpConfig.Protocol.values().length)).shutdown();
+  }
+
+  @Test
+  void buildWithDefaultsDoesNotThrow() {
+    // Exercises the default-path sender construction (real OtlpHttpSender) without
+    // actually sending anything — start/close only. Guards against a default config
+    // that would otherwise fail at construction time.
+    assertDoesNotThrow(
+        () -> {
+          OtlpWriter writer = OtlpWriter.builder().build();
+          writer.start();
+          writer.close();
+        });
+  }
+}