Migrate dd-trace-core groovy files to java part 6

we migrate 6 tests
 - PendingTracerBufferTest
 - PendingTraceStrictWriteTest
 - PendingTraceTest
 - PendingTraceTestBase
 - TraceInterceptorTest
 - TracingConfigPollerTest

Author: jpbempel

dd-trace-core/src/main/java/datadog/trace/common/writer/ListWriter.java

@@ -33,6 +33,10 @@ public List<DDSpan> firstTrace() {
     return get(0);
   }
 
+  public int getTraceCount() {
+    return traceCount.get();
+  }
+
   @SuppressFBWarnings("NN_NAKED_NOTIFY")
   @Override
   public void write(List<DDSpan> trace) {

dd-trace-core/src/main/java/datadog/trace/core/CoreTracer.java

@@ -1391,6 +1391,11 @@ public String getSpanId(AgentSpan span) {
     return "0";
   }
 
+  // @VisibleForTesting
+  TraceInterceptors getInterceptors() {
+    return interceptors;
+  }
+
   @Override
   public boolean addTraceInterceptor(final TraceInterceptor interceptor) {
     TraceInterceptor conflictingInterceptor = interceptors.add(interceptor);

dd-trace-core/src/main/java/datadog/trace/core/DDSpan.java

@@ -125,7 +125,8 @@ static DDSpan create(
    * @param timestampMicro if greater than zero, use this time instead of the current time
    * @param context the context used for the span
    */
-  private DDSpan(
+  // @VisibleForTesting
+  DDSpan(
       @Nonnull String instrumentationName,
       final long timestampMicro,
       @Nonnull DDSpanContext context,
@@ -680,6 +681,11 @@ public long getDurationNano() {
     return durationNano;
   }
 
+  // @VisibleForTesting
+  void setDurationNano(long duration) {
+    DURATION_NANO_UPDATER.set(this, duration);
+  }
+
   @Override
   public String getServiceName() {
     return context.getServiceName();

dd-trace-core/src/main/java/datadog/trace/core/PendingTrace.java

@@ -139,7 +139,8 @@ public PendingTrace create(@Nonnull DDTraceId traceId, ConfigSnapshot traceConfi
   private static final AtomicLongFieldUpdater<PendingTrace> LAST_REFERENCED =
       AtomicLongFieldUpdater.newUpdater(PendingTrace.class, "lastReferenced");
 
-  private PendingTrace(
+  // @VisibleForTesting
+  PendingTrace(
       @Nonnull CoreTracer tracer,
       @Nonnull DDTraceId traceId,
       @Nonnull PendingTraceBuffer pendingTraceBuffer,
@@ -238,6 +239,26 @@ int getPendingReferenceCount() {
     return pendingReferenceCount;
   }
 
+  // @VisibleForTesting
+  PendingTraceBuffer getPendingTraceBuffer() {
+    return pendingTraceBuffer;
+  }
+
+  // @VisibleForTesting
+  DDTraceId getTraceId() {
+    return traceId;
+  }
+
+  // @VisibleForTesting
+  boolean isRootSpanWritten() {
+    return rootSpanWritten;
+  }
+
+  // @VisibleForTesting
+  int getIsEnqueued() {
+    return isEnqueued;
+  }
+
   boolean empty() {
     return 0 >= COMPLETED_SPAN_COUNT.get(this) + PENDING_REFERENCE_COUNT.get(this);
   }

dd-trace-core/src/main/java/datadog/trace/core/PendingTraceBuffer.java

@@ -308,6 +308,16 @@ public DelayingPendingTraceBuffer(
     LongRunningTracesTracker getRunningTracesTracker() {
       return runningTracesTracker;
     }
+
+    // @VisibleForTesting
+    Thread getWorker() {
+      return worker;
+    }
+
+    // @VisibleForTesting
+    MessagePassingBlockingQueue<Element> getQueue() {
+      return queue;
+    }
   }
 
   static class DiscardingPendingTraceBuffer extends PendingTraceBuffer {