#includeIn this example, we define a test suite and test function using CppUnit macros. Within the test function, we define preconditions and postconditions using CPPUNIT_ASSERT macros to ensure that the input and output of the function are within expected ranges. We also include invariants to ensure that the function works as expected at all times. Finally, we register our test suite with the CPPUNIT_TEST_SUITE_REGISTRATION macro to run the tests. Overall, CppUnit is a powerful and widely used package for implementing DBC in C++ projects. Its rich feature set and easy-to-use macros make it an excellent choice for developers seeking to improve the quality and reliability of their code.class MyTest : public CppUnit::TestFixture { CPPUNIT_TEST_SUITE(MyTest); CPPUNIT_TEST(testFunction); CPPUNIT_TEST_SUITE_END(); public: void testFunction() { // preconditions CPPUNIT_ASSERT_THROW(functionToTest(-1), std::invalid_argument); // test body int result = functionToTest(4); // postconditions CPPUNIT_ASSERT(result > 0); CPPUNIT_ASSERT(result < 100); } int functionToTest(int input) { // invariants assert(input >= 0 && input <= 10); // code to be tested int result = input * 10; // invariants assert(result >= 0 && result <= 100); return result; } }; CPPUNIT_TEST_SUITE_REGISTRATION(MyTest);