Writing tests

How to:

Using Google Test Framework

One of the most popular third-party libraries for writing tests in C++ is Google Test. First, you’ll need to install Google Test and link it with your project. Once set up, you can start writing test cases.

#include <gtest/gtest.h>

int add(int a, int b) {
    return a + b;

TEST(TestSuiteName, TestName) {
    EXPECT_EQ(3, add(1, 2));

int main(int argc, char **argv) {
    ::testing::InitGoogleTest(&argc, argv);
    return RUN_ALL_TESTS();

Save the code in a file, and compile it with the g++ compiler, linking the Google Test library. If everything is set up correctly, running the resulting executable will run the test, and if the add function works as expected, you’ll see something like:

[==========] Running 1 test from 1 test suite.
[----------] Global test environment set-up.
[----------] 1 test from TestSuiteName
[ RUN      ] TestSuiteName.TestName
[       OK ] TestSuiteName.TestName (0 ms)
[----------] 1 test from TestSuiteName (0 ms total)

[==========] 1 test from 1 test suite ran. (1 ms total)
[  PASSED  ] 1 test.

Using Catch2

Another popular testing framework for C++ is Catch2. It has a simpler syntax and doesn’t usually require linking against a library (header-only). Here’s an example of how to write a simple test with Catch2:

#define CATCH_CONFIG_MAIN  // This tells Catch to provide a main() - only do this in one cpp file
#include <catch.hpp>

int multiply(int a, int b) {
    return a * b;

TEST_CASE( "Integers are multiplied", "[multiply]" ) {
    REQUIRE( multiply(2, 3) == 6 );

Upon compiling and running this test, Catch2 provides clear output indicating whether the test passed or failed, along with any information needed to debug failures:

All tests passed (1 assertion in 1 test case)

These examples show how integrating testing frameworks into your C++ development workflow can significantly enhance the reliability and maintainability of your code.