[googletest] --- 简易使用教程

1 googletest下载/官方sample分析

1.1 googletest源码下载编译

源码下载编译

// 下载
git clone https://github.com/google/googletest
// 现在官方已经把 gtest 和 gmock 一起维护，所以这个 git 仓库还包含了 gmock。

// 编译、安装
cd googletest-main
mkdir build install
cd build
cmake -DCMAKE_INSTALL_PREFIX=../install
make -j
make install

编译设置
如果需要生成.so库，生成官方sample的二进制文件，需要对源码最外层的CMakeLists.txt进行修改
生成动态库或者静态库，需要修改BUILD_SHARED_LIBS

生成samples测试bin文件，需要修改gtest_build_samples

将L20修改为ON之后，可以在build目录下看到googletest自带的sample都编译为了可执行文件。

1.2 googletest语法

TEST宏
TEST(test_case_name, test_name) 宏用于定义一个测试用例，其中test_case_name是测试用例的名称，test_name是测试的名称。例如：

TEST(MyTestSuite, MyTest) {
    
    
  // 测试代码
}

ASSERT宏
ASSERT_() 宏用于断言结果是否符合预期，其中可以是以下几种：
ASSERT_TRUE(condition)：条件为真
ASSERT_FALSE(condition)：条件为假
ASSERT_EQ(val1, val2)：两个值相等
ASSERT_NE(val1, val2)：两个值不相等
ASSERT_LT(val1, val2)：第一个值小于第二个值
ASSERT_LE(val1, val2)：第一个值小于等于第二个值
ASSERT_GT(val1, val2)：第一个值大于第二个值
ASSERT_GE(val1, val2)：第一个值大于等于第二个值
例如：

TEST(MyTestSuite, MyTest) {
    
    
  int a = 1;
  int b = 2;
  ASSERT_TRUE(a < b);
  ASSERT_EQ(a + b, 3);
}

如果断言失败，测试用例将会失败。

EXPECT宏
EXPECT_() 宏与ASSERT_()宏的作用相同，但是如果检查失败，不会终止测试用例的执行。例如：

TEST(MyTestSuite, MyTest) {
    
    
  int a = 1;
  int b = 2;
  EXPECT_TRUE(a < b);
  EXPECT_EQ(a + b, 3);
}

ASSERT宏和EXCEPT宏的区别：
ASSERT 不通过的时候会认为是一个 fatal 的错误，退出当前函数（只是函数）。而 EXPECT 失败的话会继续运行当前函数，所以对于函数内几个失败可以同时报告出来。通常我们用 EXPECT 级别的断言就好，除非你认为当前检查点失败后函数的后续检查没有意义。

SetUp和TearDown
SetUp() 和 TearDown() 函数可以在每个测试用例执行前和执行后分别调用，用于初始化和清理测试环境。例如：

class MyTestSuite : public ::testing::Test {
    
    
 protected:
  void SetUp() override {
    
    
    // 初始化代码
  }

  void TearDown() override {
    
    
    // 清理代码
  }
};

TEST_F(MyTestSuite, MyTest) {
    
    
  // 测试代码
}

参数化测试
参数化测试可以用于测试一组输入的不同情况下，程序的输出是否符合预期。例如：

class MyTestSuite : public ::testing::TestWithParam<int> {
    
    
};

TEST_P(MyTestSuite, MyTest) {
    
    
  int input = GetParam();
  // 测试代码
}

INSTANTIATE_TEST_SUITE_P(MyTestSuiteInstantiationName, MyTestSuite, ::testing::Values(1, 2, 3));

在这个例子中，MyTestSuite 继承自 TestWithParam，表示这是一个参数化测试。GetParam() 函数可以获取当前测试用例的参数值。INSTANTIATE_TEST_SUITE_P 宏用于实例化测试用例，其中第一个参数是实例化的名称，第二个参数是测试用例的名称，第三个参数是参数值列表。

预期异常
有时候需要测试程序在出现异常时的行为，可以使用 EXPECT_THROW() 和 ASSERT_THROW() 宏。例如：

TEST(MyTestSuite, MyTest) {
    
    
  std::vector<int> v;
  EXPECT_THROW(v.at(0), std::out_of_range);
}

在这个例子中，EXPECT_THROW() 宏表示期望在执行 v.at(0) 时抛出 std::out_of_range 异常。如果没有抛出异常，测试用例将失败。

1.3 官方sample分析

我们安装时下载的代码就包含了 10 个例子，可以直接在根目录下执行 make 并运行。进入 samples 文件夹，阅读每份功能代码和对应的测试文件，可以帮助我们较快入门。我们下面看一下简单的例子。

sample1

#include <limits.h>
#include "sample1.h"
#include "gtest/gtest.h"

// Tests factorial of negative numbers.
TEST(FactorialTest, Negative) {
    
    
  // This test is named "Negative", and belongs to the "FactorialTest"
  // test case.
  EXPECT_EQ(1, Factorial(-5));
  EXPECT_EQ(1, Factorial(-1));
  EXPECT_GT(Factorial(-10), 0);
}

...

TEST(IsPrimeTest, Positive) {
    
    
  EXPECT_FALSE(IsPrime(4));
  EXPECT_TRUE(IsPrime(5));
  EXPECT_FALSE(IsPrime(6));
  EXPECT_TRUE(IsPrime(23));
}

sample1 演示了简单测试用例的编写，主要使用了 TEST() 宏。
一个 test_case_name 对应一个函数的测试用例，test_name 可以对应这个测试用例下的某个场景的测试集。这两个名字可以任意取，但应该是有意义的.

sample1运行结果如下：

2 在自己的代码中使用gtest

上面已经说了如何将gtest编译成库，在自己项目中使用gtest时需要将install的头文件和库文件包含在记录的项目目录中。

项目目录如下：

// CMakeLists.txt
cmake_minimum_required(VERSION 3.10)
project(GTEST_USAGE)
set(CMAKE_CXX_COMPILE_FLAGS "std=c++11")

include_directories(${
    
    CMAKE_CURRENT_SOURCE_DIR}/install/include)
file(GLOB CPP_FILES ${
    
    CMAKE_CURRENT_SOURCE_DIR}/*.c*)
link_directories(${CMAKE_CURRENT_SOURCE_DIR}/install/lib)
add_executable(GTEST_USAGE ${CPP_FILES})

target_link_libraries(GTEST_USAGE 
gtest
)

// main.cpp
#include <gtest/gtest.h>
#include<numeric>

int main(int argc, char **argv)
{
	testing::InitGoogleTest(&argc, argv)
	return 0;
}

这里我不写自己的代码，直接用官方的sample4充当测试代码
sample4.cc

// Copyright 2005, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// A sample program demonstrating using Google C++ testing framework.

#include "sample4.h"

#include <stdio.h>

// Returns the current counter value, and increments it.
int Counter::Increment() {
    
     return counter_++; }

// Returns the current counter value, and decrements it.
// counter can not be less than 0, return 0 in this case
int Counter::Decrement() {
    
    
  if (counter_ == 0) {
    
    
    return counter_;
  } else {
    
    
    return counter_--;
  }
}

// Prints the current counter value to STDOUT.
void Counter::Print() const {
    
     printf("%d", counter_); }

sample4.h

// Copyright 2005, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// A sample program demonstrating using Google C++ testing framework.
#ifndef GOOGLETEST_SAMPLES_SAMPLE4_H_
#define GOOGLETEST_SAMPLES_SAMPLE4_H_

// A simple monotonic counter.
class Counter {
    
    
 private:
  int counter_;

 public:
  // Creates a counter that starts at 0.
  Counter() : counter_(0) {
    
    }

  // Returns the current counter value, and increments it.
  int Increment();

  // Returns the current counter value, and decrements it.
  int Decrement();

  // Prints the current counter value to STDOUT.
  void Print() const;
};

#endif  // GOOGLETEST_SAMPLES_SAMPLE4_H_

sample4_unittest.cc

// Copyright 2005, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include "sample4.h"

#include "gtest/gtest.h"

namespace {
    
    
// Tests the Increment() method.

TEST(Counter, Increment) {
    
    
  Counter c;

  // Test that counter 0 returns 0
  EXPECT_EQ(0, c.Decrement());

  // EXPECT_EQ() evaluates its arguments exactly once, so they
  // can have side effects.

  EXPECT_EQ(0, c.Increment());
  EXPECT_EQ(1, c.Increment());
  EXPECT_EQ(2, c.Increment());

  EXPECT_EQ(3, c.Decrement());
}

}  // namespace

运行结果如下：