**Course Title:** Modern C++ Programming: Mastering C++ with Best Practices and Advanced Techniques **Section Title:** Testing, Debugging, and Profiling **Topic:** Write unit tests for your C++ code and use a debugging tool to track down and fix a memory issue.(Lab topic) **Objective:** In this lab, you will learn how to write unit tests for your C++ code using the Google Test framework and how to use the Valgrind debugging tool to track down and fix a memory issue. **Introduction to Unit Testing with Google Test:** Google Test is a popular testing framework for C++ that allows you to write unit tests for your code. To use Google Test, you need to include the `gtest/gtest.h` header file in your test files. **Example: Writing a Unit Test with Google Test** ```cpp // my_math.h #ifndef MY_MATH_H #define MY_MATH_H int add(int a, int b); #endif // MY_MATH_H ``` ```cpp // my_math.cpp #include "my_math.h" int add(int a, int b) { return a + b; } ``` ```cpp // my_math_test.cpp #include "gtest/gtest.h" #include "my_math.h" TEST(MathTest, Add) { EXPECT_EQ(add(1, 2), 3); EXPECT_EQ(add(-1, 1), 0); EXPECT_EQ(add(-1, -1), -2); } int main(int argc, char **argv) { ::testing::InitGoogleTest(&argc, argv); return RUN_ALL_TESTS(); } ``` **Compiling and Running the Test** To compile and run the test, you need to compile the `my_math.cpp` file and the `my_math_test.cpp` file using the following commands: ```bash g++ -c my_math.cpp -o my_math.o g++ -c my_math_test.cpp -o my_math_test.o -I/path/to/gtest/include g++ my_math.o my_math_test.o -o my_math_test -L/path/to/gtest/lib -l/gtest ./my_math_test ``` **Introduction to Valgrind:** Valgrind is a debugging tool that allows you to detect memory errors in your C++ code. To use Valgrind, you need to compile your code with debugging information enabled using the `-g` flag. **Example: Using Valgrind to Detect a Memory Error** ```cpp // my_program.cpp #include <iostream> int main() { int* x = new int; *x = 5; std::cout << *x << std::endl; // Delete the memory, but using delete[] will cause a memory error delete x; return 0; } ``` **Compiling and Running Valgrind** To compile and run Valgrind, you need to compile the `my_program.cpp` file with debugging information enabled using the following commands: ```bash g++ -g my_program.cpp -o my_program valgrind --leak-check=full ./my_program ``` **Fixing the Memory Error** To fix the memory error, you need to use the `delete[]` operator instead of the `delete` operator to delete the memory. ```cpp // my_program.cpp (fixed) #include <iostream> int main() { int* x = new int; *x = 5; std::cout << *x << std::endl; delete[] x; return 0; } ``` **Conclusion** In this lab, you learned how to write unit tests for your C++ code using the Google Test framework and how to use the Valgrind debugging tool to track down and fix a memory issue. You also learned how to compile and run your code with debugging information enabled using the `-g` flag. **Additional Resources** * Google Test Documentation: [https://github.com/google/googletest](https://github.com/google/googletest) * Valgrind Documentation: [https://valgrind.org/docs/manual/index.html](https://valgrind.org/docs/manual/index.html) **Questions and Help** If you have any questions or need help with this lab, feel free to ask. There will not be a discussion board for this topic. Please leave a comment below if you need assistance. Next topic: Introduction to C++20 features: Modules, coroutines, and concepts.