diff --git a/test/test_data_type.cpp b/test/test_data_type.cpp
index 9ab4ac01d7761c77460697a7b264fa7d7b9a8401..44347b3a221542c8c0e0603753446b0786b4ecfa 100644
--- a/test/test_data_type.cpp
+++ b/test/test_data_type.cpp
@@ -48,6 +48,7 @@ TEST(test_data_type, test_atomic) {
   for (int i = 1; i < 6; i++) {
     Entity entity;
     entity.SetRole(Role::PROPERTY);
+    // the different AtomicDataType are associated with integers
     entity.SetDataType(static_cast<AtomicDataType>(i));
     EXPECT_TRUE(entity.GetDataType().IsAtomic());
     EXPECT_EQ(entity.GetDataType().AsAtomic(), static_cast<AtomicDataType>(i));
@@ -57,6 +58,7 @@ TEST(test_data_type, test_atomic) {
     entity.SetDataType(data_type);
 
     EXPECT_FALSE(data_type.IsReference());
+    EXPECT_EQ(data_type.AsReference().GetName(), std::basic_string<char>(""));
     EXPECT_FALSE(data_type.IsList());
     EXPECT_TRUE(data_type.IsAtomic());
     EXPECT_EQ(data_type.AsAtomic(), static_cast<AtomicDataType>(i));
@@ -95,6 +97,7 @@ TEST(test_data_type, test_list_of_atomic) {
     EXPECT_FALSE(data_type.IsAtomic());
     EXPECT_TRUE(data_type.IsList());
     const auto &list_data_type = data_type.AsList();
+    EXPECT_EQ(list_data_type.GetReferenceDataType().GetName(), std::basic_string<char>(""));
     EXPECT_TRUE(list_data_type.IsListOfAtomic());
     EXPECT_FALSE(list_data_type.IsListOfReference());
     EXPECT_EQ(list_data_type.GetAtomicDataType(),
diff --git a/test/test_entity.cpp b/test/test_entity.cpp
index f38f14457bf0b9a3fc5ddf21820615b55fd6f484..9d09e45b45580808768a8ca38528a4cbfc1988e7 100644
--- a/test/test_entity.cpp
+++ b/test/test_entity.cpp
@@ -30,12 +30,14 @@
 #include "caosdb/status_code.h"                  // for StatusCode, FILE_DO...
 #include "caosdb/transaction.h"                  // for Transaction
 #include "caosdb/value.h"                        // for Value
+#include <exception>
 #include <google/protobuf/arena.h>               // for Arena
 #include <gtest/gtest-message.h>                 // for Message
 #include <gtest/gtest-test-part.h>               // for TestPartResult, Sui...
 #include <gtest/gtest_pred_impl.h>               // for Test, EXPECT_EQ
 #include <iostream>
 #include <memory> // for allocator, shared_ptr
+#include <stdexcept>
 #include <string> // for operator+, string
 
 namespace caosdb::entity {
@@ -100,7 +102,10 @@ TEST(test_entity, test_append_property) {
   entity.AppendProperty(prop);
   EXPECT_EQ(entity.GetProperties().size(), 1);
 
+  // also test RepeatedPtrFieldWrapper.at()
   const auto &same_prop = entity.GetProperties().at(0);
+  EXPECT_THROW((void) entity.GetProperties().at(2), std::out_of_range);
+  EXPECT_THROW((void) entity.GetProperties().at(-1), std::out_of_range);
 
   EXPECT_EQ(prop.GetName(), same_prop.GetName());
   EXPECT_EQ(prop.GetId(), same_prop.GetId());