A guide to unit testing C++ functions

C Unit testing is the process of verifying the behavior of a single function. Available frameworks include: Google Test (Googletest) Catch2Boost.Test unit testing provides advanced features such as mock objects, data-driven testing, and parameterized testing. Use cases can be used to isolate and test functions, such as those that calculate a user's account balance. Functional unit testing is a key practice for improving C code quality and simplifying maintenance.

C Functional Unit Testing Guide

Introduction

Functional unit testing is isolation and the process of validating the behavior of a single function or module without relying on other components. In C, unit testing can help you improve code quality, increase confidence in errors, and simplify code maintenance.

Framework Selection

There are many C unit testing frameworks to choose from, such as:

• Google Test (Googletest) : A popular and widely used framework that provides rich functionality.
• Catch2: A modern and lightweight framework with a clear and easy-to-use API.
• Boost.Test: Part of the Boost C library, providing a variety of unit testing tools.

HelloWorld Example

Suppose we have a function called add that adds two numbers. Let’s write a unit test using Googletest:

#include <gtest/gtest.h>

TEST(AddFunctionTest, SimpleAddition) {
    EXPECT_EQ(add(1, 2), 3);
}

1. TEST The macro creates a test case named AddFunctionTest.
2. SimpleAddition is a test method.
3. EXPECT_EQ Assert function result is 3.

Advanced features

The unit testing framework also provides various advanced features, such as:

• Mock Object: Used to simulate dependent objects.
• Data-driven testing: Run tests using different data sets.
• Parameterized testing: Run the same origin with different parameter values.

Practical Case

In the online banking system, there is a key function used to calculate the user account balance. This function reads the balance in the database and adds it to the transaction history.

Using unit testing, we can isolate and test the function. We can create the following test cases:

TEST(AccountBalanceTest, GetBalance) {
    Account account(123);
    EXPECT_EQ(account.getBalance(), 1000);
}

TEST(AccountBalanceTest, AddTransaction) {
    Account account(123);
    account.addTransaction(500);
    EXPECT_EQ(account.getBalance(), 1500);
}

These tests verify that the function calculates the balance correctly and handles transactions correctly.

Conclusion

Functional unit testing is a key practice to improve the quality of your C code. It enables you to isolate and verify the behavior of individual functions, increasing confidence in errors and simplifying code maintenance. By using a unit testing framework and advanced features, you can create powerful and maintainable code.

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