本文以结合gtest github内容进行学习gtest。

gtest github地址

g++ xx.cpp xx.h -lgtest -lpthread -o main

1.使用TEST()宏来定义和命名测试函数，这些是不返回值的普通C ++函数。
2.在此函数中，与要包含的任何有效C ++语句一起使用各种googletest断言来检查值.(ASSERT_()、EXPECT_())
3.测试的结果由断言决定; 如果测试中的任何断言失败（无论是致命的还是非致命的），或者测试崩溃，整个测试都会失败。否则，它会成功。

TEST()第一个参数是测试用例的名称，第二个参数是测试用例中的测试名称（有效的C++标识符，不应包含下划线）。
googletest按照测试用例对测试结果进行分组。

文件	描述
sample1.cc	待测试代码包含两个函数： 1：Factorial(int n) 阶乘函数。 2：IsPrime(int n) 是否是质数
sample1.h	待测试代码头文件
simple1_unittest.cc	测试用例代码文件
main.cpp	程序入口文件

代码如下:

sample1.h

#ifndef GTEST_SAMPLES_SAMPLE1_H_
#define GTEST_SAMPLES_SAMPLE1_H_

// Returns n! (the factorial of n).  For negative n, n! is defined to be 1.
int Factorial(int n);

// Returns true iff n is a prime number.
bool IsPrime(int n);

#endif  // GTEST_SAMPLES_SAMPLE1_H_

sample.cc

#include "sample1.h"

// Returns n! (the factorial of n).  For negative n, n! is defined to be 1.
int Factorial(int n) {
  int result = 1;
  for (int i = 1; i <= n; i++) {
    result *= i;
  }

  return result;
}

// Returns true iff n is a prime number.
bool IsPrime(int n) {
  // Trivial case 1: small numbers
  if (n <= 1) return false;

  // Trivial case 2: even numbers
  if (n % 2 == 0) return n == 2;

  // Now, we have that n is odd and n >= 3.

  // Try to divide n by every odd number i, starting from 3
  for (int i = 3; ; i += 2) {
    // We only have to try i up to the square root of n
    if (i > n/i) break;

    // Now, we have i <= n/i < n.
    // If n is divisible by i, n is not prime.
    if (n % i == 0) return false;
  }

  // n has no integer factor in the range (1, n), and thus is prime.
  return true;
}

sample1_unittest.cc

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

// Tests Factorial().

// 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)) << "this sunrise test"; //后面的信息在失败的情况下输出到终端
  EXPECT_EQ(1, Factorial(-1));
  EXPECT_GT(Factorial(-10), 0);

// Tests factorial of 0.
TEST(FactorialTest, Zero) {
  EXPECT_EQ(1, Factorial(0));
}

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


// Tests IsPrime()

// Tests negative input.
TEST(IsPrimeTest, Negative) {
  // This test belongs to the IsPrimeTest test case.

  EXPECT_FALSE(IsPrime(-1));
  EXPECT_FALSE(IsPrime(-2));
  EXPECT_FALSE(IsPrime(INT_MIN));
}

// Tests some trivial cases.
TEST(IsPrimeTest, Trivial) {
  EXPECT_FALSE(IsPrime(0));
  EXPECT_FALSE(IsPrime(1));
  EXPECT_TRUE(IsPrime(2));
  EXPECT_TRUE(IsPrime(3));
}

// Tests positive input.
TEST(IsPrimeTest, Positive) {
  EXPECT_FALSE(IsPrime(4));
  EXPECT_TRUE(IsPrime(5));
  EXPECT_FALSE(IsPrime(6));
  EXPECT_TRUE(IsPrime(23));
}
} // namespace

main.cpp

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

using namespace std;

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

编译命令：

g++ sample1.cc sample1.h sample1_unittest.cc main.cpp -lgtest -lpthread -o main

运行效果如下：

Running main[==========] Running 6 tests from 2 test cases.
[----------] Global test environment set-up.
[----------] 3 tests from FactorialTest
[ RUN      ] FactorialTest.Negative
[       OK ] FactorialTest.Negative (0 ms)
[ RUN      ] FactorialTest.Zero
[       OK ] FactorialTest.Zero (0 ms)
[ RUN      ] FactorialTest.Positive
[       OK ] FactorialTest.Positive (0 ms)
[----------] 3 tests from FactorialTest (0 ms total)

[----------] 3 tests from IsPrimeTest
[ RUN      ] IsPrimeTest.Negative
[       OK ] IsPrimeTest.Negative (0 ms)
[ RUN      ] IsPrimeTest.Trivial
[       OK ] IsPrimeTest.Trivial (0 ms)
[ RUN      ] IsPrimeTest.Positive
[       OK ] IsPrimeTest.Positive (0 ms)
[----------] 3 tests from IsPrimeTest (0 ms total)

[----------] Global test environment tear-down
[==========] 6 tests from 2 test cases ran. (0 ms total)
[  PASSED  ] 6 tests.

更改FactorialTest.Negative中的用例代码

// EXPECT_EQ(1, Factorial(-5)) << "this sunrise test"; //后面的信息在失败的情况下输出到终端
EXPECT_EQ(-1, Factorial(-5)) << "this sunrise test";

运行效果：

Running main[==========] Running 6 tests from 2 test cases.
[----------] Global test environment set-up.
[----------] 3 tests from FactorialTest
[ RUN      ] FactorialTest.Negative
sample1_unittest.cc:79: Failure
Value of: Factorial(-5)
  Actual: 1
Expected: -1
this sunrise test
[  FAILED  ] FactorialTest.Negative (0 ms)
[ RUN      ] FactorialTest.Zero
[       OK ] FactorialTest.Zero (0 ms)
[ RUN      ] FactorialTest.Positive
[       OK ] FactorialTest.Positive (0 ms)
[----------] 3 tests from FactorialTest (0 ms total)

[----------] 3 tests from IsPrimeTest
[ RUN      ] IsPrimeTest.Negative
[       OK ] IsPrimeTest.Negative (0 ms)
[ RUN      ] IsPrimeTest.Trivial
[       OK ] IsPrimeTest.Trivial (0 ms)
[ RUN      ] IsPrimeTest.Positive
[       OK ] IsPrimeTest.Positive (0 ms)
[----------] 3 tests from IsPrimeTest (0 ms total)

[----------] Global test environment tear-down
[==========] 6 tests from 2 test cases ran. (0 ms total)
[  PASSED  ] 5 tests.
[  FAILED  ] 1 test, listed below:
[  FAILED  ] FactorialTest.Negative

 1 FAILED TEST

分为ASSERT_*和EXPECT_*两种类型：

ASSERT_*	EXPECT_*
致命的断言，终止当前功能(以测试用例为组)	非致命故障，不会终止当前功能

终止：是终止自身处于的那一组测试用例,如上例中的FactorialTest.Negative是一组测试。

• 基本函数，基本的真/假条件测试。

Fatal assertion	Nonfatal assertion	Verifies
ASSERT_TRUE(condition);	EXPECT_TRUE(condition);	condition is true
ASSERT_FALSE(condition);	EXPECT_FALSE(condition);	condition is false

• 二元比较

Fatal assertion	Nonfatal assertion	Verifies
ASSERT_EQ(val1, val2);	EXPECT_EQ(val1, val2);	val1 == val2
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

• 字符串比较

Fatal assertion	Nonfatal assertion	Verifies
ASSERT_STREQ(str1, str2);	EXPECT_STREQ(str1, str2);	the two C strings have the same content
ASSERT_STRNE(str1, str2);	EXPECT_STRNE(str1, str2);	the two C strings have different contents
ASSERT_STRCASEEQ(str1, str2);	EXPECT_STRCASEEQ(str1, str2);	the two C strings have the same content, ignoring case
ASSERT_STRCASENE(str1, str2);	EXPECT_STRCASENE(str1, str2);	the two C strings have different contents, ignoring case

Fixtures 是测试中非常重要的一部分。他们的主要目的是建立一个固定/已知的环境状态以确保 测试可重复并且按照预期方式运行。

1. 创建Fixture类继承至::testing::Test.
2. 在类中，声明需要使用的对象
3. 编写SetUp函数
4. 编写TearDown函数
5. 如果需要，请为要共享的测试定义子例程。

例子:
Fixtures类

class QueueTest : public ::testing::Test {
 protected:
  void SetUp() override {
     q1_.Enqueue(1);
     q2_.Enqueue(2);
     q2_.Enqueue(3);
  }

  // void TearDown() override {}

  Queue<int> q0_;
  Queue<int> q1_;
  Queue<int> q2_;
};

测试用例

TEST_F(QueueTest, IsEmptyInitially) {
  EXPECT_EQ(q0_.size(), 0);
}

TEST_F(QueueTest, DequeueWorks) {
  // construct an instance QueueTest q;q.SetUp()
  int* n = q0_.Dequeue();
  EXPECT_EQ(n, nullptr);

  n = q1_.Dequeue();
  ASSERT_NE(n, nullptr);
  EXPECT_EQ(*n, 1);
  EXPECT_EQ(q1_.size(), 0);
  delete n;

  n = q2_.Dequeue();
  ASSERT_NE(n, nullptr);
  EXPECT_EQ(*n, 2);
  EXPECT_EQ(q2_.size(), 1);
  delete n;
  // q.TearDown()
}

用例DequeueWorks和用例DequeueWorks共用的QueueTest中的q0_,q1_,q2_,SetUp()和TearDown().