What are the best practices for unit testing C++ functions?

C Unit testing best practices include using an assertion library such as GTest to verify expected results. Create independent test cases for each use case. Use exception handling to check for abnormal conditions. Follow the DRY principle and reduce duplication by reusing code. Cover all code paths and ensure all branches and paths are tested. Avoid testing implementation details and focus on public interfaces. Write effective error messages that provide debugging information.

Best Practices for C Function Unit Testing

Unit testing is an integral part of software development, it helps To ensure the accuracy and reliability of the code. When unit testing in C, it's crucial to follow best practices.

1. Use the assertion library

Code example:

#include <gtest/gtest.h>

TEST(MyClass, AddNumbers) {
  ASSERT_EQ(3, MyClass().add(1, 2)); // 断言相加结果等于 3
}

2. Create tests for each use case Use case

Code example:

TEST(MyClass, AddNegativeNumbers) {
  ASSERT_EQ(-1, MyClass().add(-1, -2)); // 断言相加负数结果等于 -1
}

3. Using exception handling

Code example:

TEST(MyClass, GetValue) {
  ASSERT_THROW(MyClass().getValue(-1), std::out_of_range); // 断言尝试获取超出范围的值引发异常
}

4. Follow the DRY principle

The DRY principle (Don't Repeat Yourself) means avoiding repeated code. Code can be reused between test cases by using firmware capabilities and parameterized tests.

Code Example:

template <typename T>
void testAdd(T a, T b, T expectedResult) {
  ASSERT_EQ(expectedResult, MyClass().add(a, b));
}

TEST(MyClass, AddNumbers) {
  testAdd(1, 2, 3);
  testAdd(1.23, 4.56, 5.79);
}

5. Cover all code paths

Ensure test cases cover all possible branches and paths Crucial. Use coverage tools or manually review code paths to ensure test coverage.

Code example:

TEST(MyClass, AddNumbers) {
  ASSERT_EQ(3, MyClass().add(1, 2)); // 测试正常情况
  ASSERT_EQ(0, MyClass().add(0, 0)); // 测试特殊情况
}

6. Avoid testing implementation details

Unit tests should target the exposure of the function being tested interface to avoid testing implementation details. This helps improve the robustness and maintainability of your tests.

7. Write effective error messages

Clear and helpful error messages are critical for debugging when a test fails. Make sure the error message indicates the reason for the failure and provides contextual information.

Code example:

ASSERT_TRUE(MyClass().isValid(input)) << "输入无效：\"" << input << "\"";

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