diff --git a/polymorphism/test/CMakeLists.txt b/polymorphism/test/CMakeLists.txt
index d351f0c..8ae12fd 100644
--- a/polymorphism/test/CMakeLists.txt
+++ b/polymorphism/test/CMakeLists.txt
@@ -15,17 +15,22 @@ add_library(polymorphism_lib
 )
 
 target_compile_features(polymorphism_lib PUBLIC cxx_std_23)
-target_include_directories(polymorphism_lib PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/../include)
-target_include_directories(polymorphism_lib PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/../src)
+target_include_directories(polymorphism_lib
+    PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/../include
+    PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/../src)
 
 add_executable(test_consume
-    test_consume.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/src/test_consume.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/src/mocking.cpp
 )
 
 target_compile_features(test_consume PUBLIC cxx_std_23)
-
-target_include_directories(test_consume PUBLIC ../include)
-target_include_directories(test_consume PUBLIC "${ut_SOURCE_DIR}")
+target_include_directories(test_consume
+    PRIVATE
+    ${CMAKE_CURRENT_SOURCE_DIR}/../include
+    "${ut_SOURCE_DIR}"
+    ${CMAKE_CURRENT_SOURCE_DIR}/include
+    ${CMAKE_CURRENT_SOURCE_DIR}/../src)
 
 target_link_libraries(test_consume PRIVATE polymorphism_lib)
 
diff --git a/polymorphism/test/include/test_polymorphism/mocking.hpp b/polymorphism/test/include/test_polymorphism/mocking.hpp
new file mode 100644
index 0000000..182aef5
--- /dev/null
+++ b/polymorphism/test/include/test_polymorphism/mocking.hpp
@@ -0,0 +1,33 @@
+#ifndef POYMORPHISM_MOCKING_HPP
+#define POYMORPHISM_MOCKING_HPP
+
+#include <cstddef>
+#include <list>
+#include <string>
+
+namespace mocking {
+
+struct Mock {
+    std::list<std::string> collectedSetArguments;
+    mutable std::size_t numberOfCallsToCoolFeature { 0 };
+
+    std::string coolFeature() const
+    {
+        ++numberOfCallsToCoolFeature;
+
+        if (0 != collectedSetArguments.size()) {
+            return collectedSetArguments.back();
+        } else {
+            return "<default value>";
+        }
+    }
+
+    void set(std::string s)
+    {
+        collectedSetArguments.emplace_back(std::move(s));
+    }
+};
+
+} // namespace mocking
+
+#endif // POYMORPHISM_MOCKING_HPP
\ No newline at end of file
diff --git a/polymorphism/test/src/mocking.cpp b/polymorphism/test/src/mocking.cpp
new file mode 100644
index 0000000..9089aeb
--- /dev/null
+++ b/polymorphism/test/src/mocking.cpp
@@ -0,0 +1,7 @@
+#include <consume_class_that_adheres_to_concept.ipp>
+#include <test_polymorphism/mocking.hpp>
+
+#include <string>
+
+// explicit instantiation of consume() for Mock
+template std::string modern::consume<mocking::Mock>(mocking::Mock&);
diff --git a/polymorphism/test/test_consume.cpp b/polymorphism/test/src/test_consume.cpp
similarity index 61%
rename from polymorphism/test/test_consume.cpp
rename to polymorphism/test/src/test_consume.cpp
index 1d7f51b..133eab6 100644
--- a/polymorphism/test/test_consume.cpp
+++ b/polymorphism/test/src/test_consume.cpp
@@ -5,6 +5,8 @@
 #include <polymorphism/impl_with_interface.hpp>
 #include <polymorphism/impl_without_interface.hpp>
 
+#include <test_polymorphism/mocking.hpp>
+
 int main()
 {
     using namespace boost::ut;
@@ -37,6 +39,30 @@ int main()
                           expect("The answer to all questions is 42"s == result);
                       };
 
+                      then("the state of the argument should be modified as a side effect") = [=] {
+                          expect("42"s == impl.coolFeature());
+                      };
+                  };
+              };
+          };
+
+    "[modern mock]"_test
+        = [] {
+              given("I have a an mock that adheres to a concept") = [] {
+                  mocking::Mock impl;
+                  expect("<default value>"s == impl.coolFeature());
+
+                  when("I pass it to a function that expects an argument that fulfils the constraints") = [&] {
+                      auto result = modern::consume(impl);
+
+                      then("set() should be called twice") = [=] {
+                          expect(2 == impl.numberOfCallsToCoolFeature);
+                      };
+
+                      then("the answer to all questions should be given") = [=] {
+                          expect("The answer to all questions is 42"s == result);
+                      };
+
                       then("the state of the argument should be modified as a side effect") = [=] {
                           expect("42"s == impl.coolFeature());
                       };