Mac下GTest的基本使用

gtest全称Google C++ Testing Framework，它是从谷歌内部诞生并受到业界追捧的一个非常优秀的测试框架，支持如自动发现测试、自定义断言、死亡测试、自动报告等诸多功能。

本文记录Mac下安装配置gtest以及它的基本应用

一、安装

博主尝试用brew install 遇到了问题，于是直接源码安装

编译安装

 git clone https://github.com/google/googletest
 cd googletest
 mkdir build && cd build
 cmake ..
 make
 make install

测试代码

CMakeLists.txt

cmake_minimum_required(VERSION 3.0)
set(CMAKE_CXX_STANDARD 11)

project(demo)

find_package(GTEST REQUIRED)

add_executable(${PROJECT_NAME} main.cpp)

target_link_libraries(${PROJECT_NAME} ${GTEST_LIBRARIES})

main.cpp

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

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

int sub(int a, int b) {
    return a - b;
}

// case1
TEST(test, c1) {
    EXPECT_EQ(3, add(1, 2));
    EXPECT_EQ(12, add(2, 6));
}

// case2
TEST(test, c2) {
    EXPECT_EQ(-1, sub(1, 2));
}

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

编译运行

cmake .
make
./demo
# 输出
?  build ./demo
[==========] Running 2 tests from 1 test case.
[----------] Global test environment set-up.
[----------] 2 tests from test
[ RUN      ] test.c1
/Users/fanghao/Desktop/test/main.cpp:15: Failure
Expected equality of these values:
  12
  add(2, 6)
    Which is: 8
[  FAILED  ] test.c1 (0 ms)
[ RUN      ] test.c2
[       OK ] test.c2 (0 ms)
[----------] 2 tests from test (0 ms total)

[----------] Global test environment tear-down
[==========] 2 tests from 1 test case ran. (0 ms total)
[  PASSED  ] 1 test.
[  FAILED  ] 1 test, listed below:
[  FAILED  ] test.c1

 1 FAILED TEST

二、基本概念

• 断言：即assertion，检查条件是否为真，一个断言的结果有

  • sucess
  • nonfatal failure（非致命失败）
  • fatal failure（致命失败）

  这里值得注意的是后两个，nonfatal failure会指出错误，然后继续运行，由EXPECT_XX产生，fatal failure会指出错误但是终止当前测试函数，由ASSERT_XX产生，一般推荐用前者，这样一次可以查出多个问题

• 测试样例：test case表示要测试的对象，一般TEST会有两个参数，分别是测试样例，以及测试的子case，如下面这个测试阶乘的样例，HandlesZeroInput和HandlesPositiveInput都属于FactorialTest这个测试样例

  // Tests factorial of 0
  TEST(FactorialTest, HandlesZeroInput) {
  EXPECT_EQ(1, Factorial(0));
  }
  
  // Tests factorial of positive numbers.
  TEST(FactorialTest, HandlesPositiveInput) {
  EXPECT_EQ(1, Factorial(1));
  EXPECT_EQ(2, Factorial(2));
  EXPECT_EQ(6, Factorial(3));
  EXPECT_EQ(40320, Factorial(8));
  }

• 常用断言

  Fatal assertion	Nonfatal assertion	Verifies
  ASSERT_TRUE(condition);	EXPECT_TRUE(condition);	condition is true
  ASSERT_FALSE(condition);	EXPECT_FALSE(condition);	condition is false
  ASSERT_EQ(expected, actual);	EXPECT_EQ(expected, actual);	expected == actual
  ASSERT_NE(val1, val2);	EXPECT_NE(val1, val2);	val1 != val2
  ASSERT_LT(val1, val2);	EXPECT_LT(val1, val2);	val1 < val2
  ASSERT_LE(val1, val2);	EXPECT_LE(val1, val2);	val1 <= val2
  ASSERT_GT(val1, val2);	EXPECT_GT(val1, val2);	val1 > val2
  ASSERT_GE(val1, val2);	EXPECT_GE(val1, val2);	val1 >= val2
  ASSERT_STREQ(expected_str, actual_str);	EXPECT_STREQ(expected_str, actual_str);	the two C strings have the same content
  ASSERT_STRNE(str1, str2);	EXPECT_STRNE(str1,str2);	the two C strings have different content
  ASSERT_STRCASEEQ(expected_str, actual_str);	EXPECT_STRCASEEQ(expected_str, actual_str);	the two C strings have the same content,ignore case
  ASSERT_STRCASENE(str1, str2);	EXPECT_STRCASENE(str1,str2);	the two C strings have different content,ignore case

三、 Test Fixture

Test Fixture是对基本test case的封装，如果多个test需要操作类似数据，可以把他们封装在一个类里面，然后共享一些配置。

编写Fixure步骤

1. 建立一个类，并继承::testing::Test，并且使用protected或public限制符，以便其子类可以访问到共享的数据
2. 在这个类中，声明你想复用的对象。
3. 写一个SetUp函数来准备所需对象
4. 写一个TearDown函数来释放资源
5. 其他用法和基本的test case一样，只是用TEST_F()宏代替TEST()宏，每次调用一个TEST_F都会重新运行一次SetUp和TearDown，但但成员对象可以共享

看一个示例应该更能说明问题

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

class Foo
{
  public:
    int add(int a, int b)
    {
        return a + b;
    }
    int sub(int a, int b)
    {
        return a - b;
    }
};

class FooTest : public ::testing::Test
{
  protected:
    Foo foo; // shared object
    // SetUp && TearDown will be called for every Test Case
    virtual void SetUp()
    {
        std::cout << "Code here will be called immediately after the constructor" << std::endl;
    }
    virtual void TearDown()
    {
        std::cout << "Code here will be called immediately after each test" << std::endl;
    }
};

// Test Case 1
TEST_F(FooTest, TestMethodAdd)
{
    EXPECT_EQ(3, foo.add(1, 2));
}

// Test Case 2
TEST_F(FooTest, TestMethodSub)
{
    EXPECT_EQ(-1, foo.sub(1, 2));
}

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

# 输出
?  build ./demo
[==========] Running 2 tests from 1 test case.
[----------] Global test environment set-up.
[----------] 2 tests from FooTest
[ RUN      ] FooTest.TestMethodAdd
Code here will be called immediately after the constructor
Code here will be called immediately after each test
[       OK ] FooTest.TestMethodAdd (0 ms)
[ RUN      ] FooTest.TestMethodSub
Code here will be called immediately after the constructor
Code here will be called immediately after each test
[       OK ] FooTest.TestMethodSub (0 ms)
[----------] 2 tests from FooTest (0 ms total)

[----------] Global test environment tear-down
[==========] 2 tests from 1 test case ran. (1 ms total)
[  PASSED  ] 2 tests.

四、小结

感觉gtest还是挺优雅的，适合TDD模式，把测试和开发完全解耦。