Extend W3CTraceParentTest coverage and migrate it to Java

internal-api/src/test/java/datadog/trace/api/propagation/W3CTraceParentTest.java

@@ -0,0 +1,91 @@
+package datadog.trace.api.propagation;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.params.provider.Arguments.arguments;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import datadog.trace.api.DDTraceId;
+import datadog.trace.bootstrap.instrumentation.api.AgentSpan;
+import datadog.trace.bootstrap.instrumentation.api.AgentSpanContext;
+import java.util.stream.Stream;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+public class W3CTraceParentTest {
+
+  @ParameterizedTest(name = "{0}")
+  @MethodSource("buildProducesCorrectFormatArguments")
+  void buildProducesCorrectFormat(
+      String scenario, DDTraceId traceId, long spanId, boolean isSampled, String expected) {
+    assertEquals(expected, W3CTraceParent.from(traceId, spanId, isSampled));
+  }
+
+  static Stream<Arguments> buildProducesCorrectFormatArguments() {
+    return Stream.of(
+        arguments(
+            "sampled",
+            DDTraceId.from(1),
+            2L,
+            true,
+            "00-00000000000000000000000000000001-0000000000000002-01"),
+        arguments(
+            "not sampled",
+            DDTraceId.from(1),
+            2L,
+            false,
+            "00-00000000000000000000000000000001-0000000000000002-00"),
+        arguments(
+            "W3C example",
+            DDTraceId.fromHex("0af7651916cd43dd8448eb211c80319c"),
+            0x00f067aa0ba902b7L,
+            true,
+            "00-0af7651916cd43dd8448eb211c80319c-00f067aa0ba902b7-01"),
+        arguments(
+            "Long.MAX_VALUE ids",
+            DDTraceId.from(Long.MAX_VALUE),
+            Long.MAX_VALUE,
+            true,
+            "00-00000000000000007fffffffffffffff-7fffffffffffffff-01"));
+  }
+
+  @Test
+  void buildMatchesW3CTraceparentFormat() {
+    // W3C format: version-traceId(32 hex)-spanId(16 hex)-flags(2 hex)
+    String result = W3CTraceParent.from(DDTraceId.from(123456789L), 987654321L, true);
+    assertTrue(result.matches("00-[0-9a-f]{32}-[0-9a-f]{16}-(00|01)"));
+  }
+
+  @Test
+  void buildFromSpanSampled() {
+    AgentSpan span = mock(AgentSpan.class);
+    AgentSpanContext context = mock(AgentSpanContext.class);
+    DDTraceId traceId = DDTraceId.fromHex("0af7651916cd43dd8448eb211c80319c");
+    long spanId = 0x00f067aa0ba902b7L;
+
+    when(span.getTraceId()).thenReturn(traceId);
+    when(span.getSpanId()).thenReturn(spanId);
+    when(span.spanContext()).thenReturn(context);
+    when(context.getSamplingPriority()).thenReturn(1);
+
+    assertEquals(
+        "00-0af7651916cd43dd8448eb211c80319c-00f067aa0ba902b7-01", W3CTraceParent.from(span));
+  }
+
+  @Test
+  void buildFromSpanNotSampled() {
+    AgentSpan span = mock(AgentSpan.class);
+    AgentSpanContext context = mock(AgentSpanContext.class);
+
+    when(span.getTraceId()).thenReturn(DDTraceId.from(1));
+    when(span.getSpanId()).thenReturn(2L);
+    when(span.spanContext()).thenReturn(context);
+    when(context.getSamplingPriority()).thenReturn(0);
+
+    assertEquals(
+        "00-00000000000000000000000000000001-0000000000000002-00", W3CTraceParent.from(span));
+  }
+}