Summary - Testing basics

Combine TEST, ASSERT and Mock to write a calculator test.

Summary: combining test tools

In this summary you will combine the TEST macro, the ASSERT/EXPECT split and fixtures in a calculator test. You will first write a Calc class, then set up shared setup with a fixture and test it with TEST_F.

The Calc class has an add(int, int) method. The CalcTest fixture prepares a Calc object in SetUp. Inside TEST_F(CalcTest, Adds) call EXPECT_EQ(calc.add(2, 3), 5). This way fixture, test and assertion work together; it is a small example of real project test structure.

Exercise Write the calculator test

Define a Calc class with public int add(int a, int b) { return a + b; }. Derive a CalcTest fixture from ::testing::Test; in SetUp prepare a Calc calc; member. Inside TEST_F(CalcTest, Adds) call EXPECT_EQ(calc.add(2, 3), 5). In main print std::cout << "test: ready";.

Show example solution

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

class Calc {
public:
    int add(int a, int b) { return a + b; }
};

class CalcTest : public ::testing::Test {
protected:
    void SetUp() override {
        calc = Calc();
    }
    Calc calc;
};

TEST_F(CalcTest, Adds) {
    EXPECT_EQ(calc.add(2, 3), 5);
}

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

Test yourself

What do fixtures and mocks provide together?
- Faster compilation
- Shared setup and isolated dependencies
- Colored output
- Fewer lines of code
Show answer

Shared setup and isolated dependencies — Fixtures give shared setup; mocks isolate dependencies.

Complete the TEST_F call

____(CalcTest, Adds) {
    EXPECT_EQ(calc.add(2, 3), 5);
}

Show answer

TEST_F(CalcTest, Adds) {
    EXPECT_EQ(calc.add(2, 3), 5);
}

Match the tool to its role

TEST

Defines a simple test
TEST_F

Defines a fixture test
EXPECT_EQ

Checks equality
MOCK_METHOD

Creates a fake method

Next lesson: CMake basics

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