resolved aditya's questions

api/test/trace/BUILD

@@ -11,6 +11,17 @@ cc_test(
     ],
 )
 
+cc_test(
+    name = "noop_test",
+    srcs = [
+        "noop_test.cc",
+    ],
+    deps = [
+        "//api",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
 cc_test(
     name = "key_value_iterable_view_test",
     srcs = [

api/test/trace/CMakeLists.txt

@@ -1,4 +1,4 @@
-foreach(testname key_value_iterable_view_test provider_test span_id_test
+foreach(testname key_value_iterable_view_test provider_test span_id_test noop_test
                  trace_id_test trace_flags_test span_context_test)
   add_executable(${testname} "${testname}.cc")
   target_link_libraries(${testname} ${GTEST_BOTH_LIBRARIES}

api/test/trace/noop_test.cc

@@ -0,0 +1,29 @@
+#include "opentelemetry/trace/noop.h"
+
+#include <map>
+#include <memory>
+#include <string>
+
+#include <gtest/gtest.h>
+
+using opentelemetry::trace::NoopTracer;
+using opentelemetry::trace::Tracer;
+
+TEST(NoopTest, UseNoopTracers)
+{
+  std::shared_ptr<Tracer> tracer{new NoopTracer{}};
+  auto s1 = tracer->StartSpan("abc");
+
+  std::map<std::string, std::string> attributes1;
+  s1->AddEvent("abc", attributes1);
+
+  std::vector<std::pair<std::string, int>> attributes2;
+  s1->AddEvent("abc", attributes2);
+
+  s1->AddEvent("abc", {{"a", 1}, {"b", "2"}, {"c", 3.0}});
+
+  std::vector<std::pair<std::string, std::vector<int>>> attributes3;
+  s1->AddEvent("abc", attributes3);
+
+  s1->SetAttribute("abc", 4);
+}