#2229: Add unit test for dumping attributes field in json data file

tests/unit/collection/test_lb.extended.cc

@@ -777,6 +777,68 @@ INSTANTIATE_TEST_SUITE_P(
   DumpUserdefinedDataExplode, TestDumpUserdefinedData, booleans
 );
 
+struct TestDumpAttributesFieldData : TestParallelHarnessParam<bool> { };
+
+TEST_P(TestDumpAttributesFieldData, test_dump_attributes_json) {
+  bool is_attribute = GetParam();
+
+  auto this_node = vt::theContext()->getNode();
+  auto num_nodes = vt::theContext()->getNumNodes();
+
+  vt::vrt::collection::CollectionProxy<MyCol> proxy;
+  auto const range = vt::Index1D(num_nodes * 1);
+
+  // Construct a collection
+  runInEpochCollective([&] {
+    proxy = vt::theCollection()->constructCollective<MyCol>(
+      range, "test_dump_attributes_json"
+    );
+  });
+
+  vt::vrt::collection::balance::LBDataHolder lbdh;
+  PhaseType phase = 0;
+
+  {
+    lbdh.node_data_[phase];
+    lbdh.node_comm_[phase];
+
+    vt::Index1D idx(this_node * 1);
+    auto elm_ptr = proxy(idx).tryGetLocalPtr();
+    EXPECT_NE(elm_ptr, nullptr);
+    if (elm_ptr != nullptr) {
+      auto elm_id = elm_ptr->getElmID();
+      elm_ptr->valInsert("intSample", 123, false, false, is_attribute);
+      elm_ptr->valInsert("doubleSample", 123.456, false, false, is_attribute);
+      elm_ptr->valInsert("stringSample", std::string("abc"), false, false, is_attribute);
+
+      elm_ptr->collectAttributes(
+        [&](std::string const& key, auto val) {
+          lbdh.node_user_attributes_[phase][elm_id][key] = val->toVariant();
+        }
+      );
+      lbdh.node_data_[phase][elm_id].whole_phase_load = 1.0;
+    }
+  }
+
+  auto json_str = getJsonStringForPhase(phase, lbdh);
+  fmt::print("{}\n", json_str);
+  if (is_attribute) {
+    EXPECT_NE(json_str.find("attributes"), std::string::npos);
+    EXPECT_NE(json_str.find("intSample"), std::string::npos);
+    EXPECT_NE(json_str.find("doubleSample"), std::string::npos);
+    EXPECT_NE(json_str.find("stringSample"), std::string::npos);
+  } else {
+    EXPECT_EQ(json_str.find("attributes"), std::string::npos);
+    EXPECT_EQ(json_str.find("intSample"), std::string::npos);
+    EXPECT_EQ(json_str.find("doubleSample"), std::string::npos);
+    EXPECT_EQ(json_str.find("stringSample"), std::string::npos);
+  }
+}
+
+INSTANTIATE_TEST_SUITE_P(
+  DumpAttributesFieldDataExplode, TestDumpAttributesFieldData, booleans
+);
+
 struct SerializationTestCol : vt::Collection<SerializationTestCol, vt::Index1D> {
   template <typename SerializerT> void serialize(SerializerT &s) {
     vt::Collection<SerializationTestCol, vt::Index1D>::serialize(s);