diff --git a/rcl/test/CMakeLists.txt b/rcl/test/CMakeLists.txt
index 411bcbf..3aac54c 100644
--- a/rcl/test/CMakeLists.txt
+++ b/rcl/test/CMakeLists.txt
@@ -353,7 +353,7 @@ call_for_each_rmw_implementation(test_target)
 rcl_add_custom_gtest(test_validate_enclave_name
   SRCS rcl/test_validate_enclave_name.cpp
   APPEND_LIBRARY_DIRS ${extra_lib_dirs}
-  LIBRARIES ${PROJECT_NAME}
+  LIBRARIES ${PROJECT_NAME} mimick
 )
 
 rcl_add_custom_gtest(test_domain_id
diff --git a/rcl/test/rcl/test_validate_enclave_name.cpp b/rcl/test/rcl/test_validate_enclave_name.cpp
index 408bdcc..0cc4b1c 100644
--- a/rcl/test/rcl/test_validate_enclave_name.cpp
+++ b/rcl/test/rcl/test_validate_enclave_name.cpp
@@ -17,11 +17,17 @@
 #include <string>
 #include <vector>
 
+#include "rcutils/snprintf.h"
+
 #include "rcl/rcl.h"
 #include "rcl/validate_enclave_name.h"
 
 #include "rcl/error_handling.h"
 
+#include "rmw/validate_namespace.h"
+
+#include "../mocking_utils/patch.hpp"
+
 TEST(TestValidateEnclaveName, test_validate) {
   int validation_result;
   size_t invalid_index;
@@ -47,6 +53,59 @@ TEST(TestValidateEnclaveName, test_validate) {
     RCL_RET_OK,
     rcl_validate_enclave_name("/foo/bar", &validation_result, &invalid_index));
   EXPECT_EQ(RCL_ENCLAVE_NAME_VALID, validation_result);
+
+  {
+    auto mock = mocking_utils::patch(
+      "lib:rcl", rmw_validate_namespace_with_size,
+      [&](auto, auto, int * result, size_t * index) {
+        if (index) {
+          *index = 0u;
+        }
+        *result = RMW_NAMESPACE_INVALID_TOO_LONG;
+        return RMW_RET_OK;
+      });
+
+    // When applying RMW namespace validation rules, an enclave name may be too
+    // long for an RMW namespace but not necessarily for an enclave name.
+    EXPECT_EQ(
+      RCL_RET_OK,
+      rcl_validate_enclave_name("/foo/baz", &validation_result, &invalid_index));
+    EXPECT_EQ(RCL_ENCLAVE_NAME_VALID, validation_result);
+  }
+}
+
+TEST(TestValidateEnclaveName, test_validate_on_internal_error) {
+  int validation_result;
+  size_t invalid_index;
+
+  {
+    auto mock = mocking_utils::patch_to_fail(
+      "lib:rcl", rmw_validate_namespace_with_size, "internal error", RMW_RET_ERROR);
+
+    EXPECT_EQ(
+      RCL_RET_ERROR,
+      rcl_validate_enclave_name("/foo", &validation_result, &invalid_index));
+    EXPECT_TRUE(rcl_error_is_set());
+    rcl_reset_error();
+  }
+
+  {
+    auto mock = mocking_utils::patch(
+      "lib:rcl", rmw_validate_namespace_with_size,
+      [&](auto, auto, int * result, size_t * index) {
+        if (index) {
+          *index = 0u;
+        }
+        *result = -1;
+        return RMW_RET_OK;
+      });
+
+    EXPECT_EQ(
+      RCL_RET_ERROR,
+      rcl_validate_enclave_name("/foo", &validation_result, &invalid_index));
+    EXPECT_TRUE(rcl_error_is_set());
+    rcl_reset_error();
+  }
 }
 
 TEST(TestValidateEnclaveName, test_validation_string) {