Quick start

GoogleTest yes Google A set of for writing C++ The framework for testing , It can run on multiple platforms ( Include Linux、MacOS X、Windows、Cygwin etc. ). be based on xUnit framework , Support many easy-to-use features , Including automatic identification test 、 Rich assertions 、 Assert custom 、 Death test 、 Non terminating failure 、 Generate XML Reports, etc .

hereinafter referred to as GTest.

GTest The advantages of

A good test should include the following features .

• The test should be independent 、 Repeatable . The result of one test should not be a prerequisite for another test .
• GTest Each test in runs in a separate object . If a test fails , You can debug it separately .
• The test should have a clear structure .
• GTest The test has a good organizational structure , Easy to maintain .
• Tests should be portable and reusable . A lot of code is platform independent , Therefore, their testing also needs to be platform independent .
• GTest Can operate on a variety of operating systems 、 Working under a variety of compilers , It has good portability .
• When the test fails , The information should be as detailed as possible .
• GTest In case of failure, do not stop the next test , You can also choose to use non terminating failures to continue the current test . In this way, you can test as many problems as possible at one time .
• The test framework should avoid allowing developers to maintain things related to the test framework .
• GTest All defined tests can be automatically identified , You don't need to list them all .
• The test should be fast enough .
• GTest On the premise of meeting the test independence , Allows you to reuse shared data , They only need to be created once .
• GTest It's using xUnit framework , You'll find out and JUnit、PyUnit Is very similar , So get started very quickly .

Build a test framework

• GTest Project address of ：https://github.com/google/googletest

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The installation process is as follows ：

1. git clone https://github.com/google/googletest.git
2. cd googletest
3. mkdir build
4. cd build
5. cmake …
6. make
7. sudo make install

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Be careful :

• If make Report an error in the process , May be gcc Version is too low , From the official project issus We can get the value of ,gcc 4.8 Version no longer supports , As shown in the figure below .linux make[1]: *** [googletest/CMakeFiles/gtest.dir/all] Error 2#3639
• 
• install gcc-5( Or later ),Ubuntu20.04 install gcc-5.
• Successfully compiled build .
• among ,/build/lib Will be generated in the directory :libgmock.a libgmock_main.a libgtest.a libgtest_main.a file .

Test examples

sample1.h

#ifndef GTEST_SAMPLES_SAMPLE1_H_
#define GTEST_SAMPLES_SAMPLE1_H_

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

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

#endif 

sample1.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 {

    //TEST( Test Suite , Test case name )
    TEST(FactorialTest, Negative) {
        // Call the corresponding function , Whether the result is 1, Determine whether the test case passes 
        EXPECT_EQ(1, Factorial(-5));
        EXPECT_EQ(1, Factorial(-1));
        EXPECT_GT(Factorial(-10), 0);
    }

    TEST(FactorialTest, Zero) {
        EXPECT_EQ(1, Factorial(0));
    }

    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()
    TEST(IsPrimeTest, Negative) {
      EXPECT_FALSE(IsPrime(-1));
      EXPECT_FALSE(IsPrime(-2));
      EXPECT_FALSE(IsPrime(INT_MIN));
    }

    TEST(IsPrimeTest, Trivial) {
      EXPECT_FALSE(IsPrime(0));
      EXPECT_FALSE(IsPrime(1));
      EXPECT_TRUE(IsPrime(2));
      EXPECT_TRUE(IsPrime(3));
    }

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

compile

g++ sample1.cc sample1_unittest.cc -lgtest -std=c++14 -lgtest_main -lpthread -o test1

Be careful :

• When this article was published ,GTest No longer supported C++11, The minimum supported version is C++14, therefore -std=c++11 Will report a mistake , Error resolution ( primary issues)——Commit e009c3d fails to build with "error: wrong number of template arguments (0, should be 1), take c++ The version is specified as c++14.（ At first I thought it was me ubuntu The version of is too low , Specially changed the machine .）

• 

• above sample1_unittest.cc In the test procedure , We didn't write main function , Because we linked gtest_main This library .

• When testing , Select representative use cases for testing .

perform

./test1

• All test cases pass
• next , Let's modify a code ( This modification judges a code in the prime number function , Return the original false The position of is changed to ture.), Recompile execution , Find the error .

Handwriting main function

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

compile : This can be removed at compile time gtest_main library .

g++ sample1.cc sample1_unittest.cc -lgtest -std=c++14  -lpthread -o test1