Fix span decoration probe EMITTING status (#7569)

Don't emit the status when no tag are set for the span

Author: jpbempel

dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/probe/SpanDecorationProbe.java

@@ -232,7 +232,10 @@ private void decorateTags(SpanDecorationStatus status) {
     for (Pair<String, String> tag : tagsToDecorate) {
       agentSpan.setTag(tag.getLeft(), tag.getRight());
     }
-    DebuggerAgent.getSink().getProbeStatusSink().addEmitting(probeId);
+    if (!tagsToDecorate.isEmpty()) {
+      // only send EMITTING status if we set at least one tag
+      DebuggerAgent.getSink().getProbeStatusSink().addEmitting(probeId);
+    }
   }
 
   private void handleEvaluationErrors(SpanDecorationStatus status) {

dd-java-agent/agent-debugger/src/test/java/com/datadog/debugger/agent/SpanDecorationProbeInstrumentationTest.java

@@ -15,6 +15,7 @@
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 import static utils.InstrumentationTestHelper.compileAndLoadClass;
@@ -155,6 +156,24 @@ public void methodActiveSpanCondition() throws IOException, URISyntaxException {
     assertEquals("5", span.getTags().get("tag1"));
   }
 
+  @Test
+  public void methodActiveSpanConditionFalse() throws IOException, URISyntaxException {
+    final String CLASS_NAME = "com.datadog.debugger.CapturedSnapshot20";
+    SpanDecorationProbe.Decoration decoration =
+        createDecoration(eq(ref("arg"), value("5")), "arg == '5'", "tag1", "{arg}");
+    installSingleSpanDecoration(
+        CLASS_NAME, ACTIVE, decoration, "process", "int (java.lang.String)");
+    Class<?> testClass = compileAndLoadClass(CLASS_NAME);
+    int result = Reflect.on(testClass).call("main", "0").get();
+    assertEquals(84, result);
+    assertEquals(1, traceInterceptor.getAllTraces().size());
+    MutableSpan span = traceInterceptor.getAllTraces().get(0).get(0);
+    // probe executed, but no tag set
+    assertFalse(span.getTags().containsKey("tag1"));
+    // EMITTING status is not sent
+    verify(probeStatusSink, times(0)).addEmitting(ArgumentMatchers.eq(PROBE_ID));
+  }
+
   @Test
   public void methodTagEvalError() throws IOException, URISyntaxException {
     final String CLASS_NAME = "com.datadog.debugger.CapturedSnapshot20";