Summary - Testing basics
- C++ course
- Advanced
- Lesson 42/83
- 5 min
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.
Practice 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";.
Starter code
#include <iostream>
#include <gtest/gtest.h>
// Define the Calc class
// Add the CalcTest fixture and TEST_F macro
int main(int argc, char** argv) {
std::cout << "test: ready";
return 0;
}Sample 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;
}Expected output
test: ready
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What do fixtures and mocks provide together?
- Faster compilation
- Shared setup and isolated dependencies Correct answer
- Colored output
- Fewer lines of code
Explanation: Fixtures give shared setup; mocks isolate dependencies.
2 Complete the TEST_F call
____(CalcTest, Adds) {
EXPECT_EQ(calc.add(2, 3), 5);
}TEST_F(CalcTest, Adds) {
EXPECT_EQ(calc.add(2, 3), 5);
}Explanation: TEST_F defines a test with a fixture.
3 Match the tool to its role
| Term | Meaning |
|---|---|
TEST |
Defines a simple test |
TEST_F |
Defines a fixture test |
EXPECT_EQ |
Checks equality |
MOCK_METHOD |
Creates a fake method |