GoogleTest

Learn the GoogleTest test framework.

What is GoogleTest?

GoogleTest (gtest) is a popular test framework for C++. It is developed by Google and open source. It provides macros to write, run and report tests. It is the standard choice for C++20 projects.

To use it you add #include <gtest/gtest.h>. Each test is defined with a TEST macro. In main you call testing::InitGoogleTest and RUN_ALL_TESTS() to run all tests. In this lesson we learn the syntax; we keep the output simple with std::cout.

The TEST macro and assertions

In GoogleTest each test is written with the TEST(SuiteName, TestName) macro. Inside the braces are assertions: EXPECT_EQ(a, b) checks that a equals b, and EXPECT_TRUE(x) checks that x is true.

Multiple tests can share a suite name to group related tests. Example: TEST(CalcTest, Adds) { EXPECT_EQ(2 + 2, 4); }. Here CalcTest is the suite and Adds is the test name. On assertion failure the test either continues (EXPECT) or stops (ASSERT); we will see this distinction next.

Exercise Write your first GoogleTest program

Add the #include <gtest/gtest.h> header. Inside TEST(SampleTest, Equals) call EXPECT_EQ(2 + 2, 4). In main print std::cout << "test: ready";.

Show example solution

#include <iostream>
#include <gtest/gtest.h>

TEST(SampleTest, Equals) {
    EXPECT_EQ(2 + 2, 4);
}

int main(int argc, char** argv) {
    std::cout << "test: ready";
    return 0;
}

Test yourself

Which header is included for GoogleTest?
- #include <gtest/gtest.h>
- #include <test.h>
- #include <iostream>
- #include <cpp/test>
Show answer

#include <gtest/gtest.h> — The <gtest/gtest.h> header enables GoogleTest.

Complete the gtest header

#include <____/gtest.h>

Show answer

#include <gtest/gtest.h>

Match each piece to its role

#include <gtest/gtest.h>

GoogleTest header
TEST(Suite, Name)

Defines a test
EXPECT_EQ(a, b)

Checks equality
RUN_ALL_TESTS()

Runs all tests

Next lesson: TEST macro

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