C++ Tutorial - Google Test (gtest)

The Framework of Google C++ Testing is based on xUnit architecture. It is a cross platform system that provides automatic test discovery. In other words, we don't have to enumerate all of the test in our test suite manually. It supports a rich set of assertions such as fatal assertions (ASSERT_), non-fatal assertions (EXPECT_), and death test which checks that a program terminates expectedly.

Here is the Primer.

GTest also provides various options for running tests and offers textual and XML report. It also supports a mock object testing framework (Google Mock).

Initially, we have a project calculating a cubic:

// simplemath.h

#include <cmath>

double cubic(double d)
{
	return pow(d,3);
}


// SimpleMath.cpp : Defines the entry point for the console application.
#include "simplemath.h"

int main()
{
	cubic(10);
	return 0;
}

In the following example, we used Visual Studio 2012 with 4 steps:

1. Download Google test
2. Compile gtest into a static library
3. Create a unit test project
4. Make a test case

Download the gtest-1.7.0-rc1.zip from Google C++ Unit Test or from gtest-1.7.0-rc1.zip, then extracts it.

Let's look at the C:\GTEST\gtest-1.7.0 directory to see what files are there.

The src folder has all the gtest source files and later we need to add the include directory to the include path.

1. Create a new static library project with a name GoogleTest.
   Add->New Project->Win32 Project->Static Library without precompiled header.
   
   
   
   
2. Right click on our new project, GoogleTest.
   On the Properties Pages, add include path:
   C:\GTEST\gtest-1.7.0 and C:\GTEST\gtest-1.7.0\include.
   
   
   
   
3. Add source files by Add->Existing Item...
   C:\GTEST\gtest-1.7.0\src\gtest_all.cc
   and C:\GTEST\gtest-1.7.0\src\gtest_main.cc.
   
   
   
   
4. Build GoogleTest into static library.
   In the build process, we may have some errors related to class template:

   VC++ 2012 does not (and will never) support variadic templates; consequently, its standard library implementation attempts to fake them using preprocessor-generated overloads and specializations. The number of faux variadic template parameters defaults to 5 - the problem is that gtest is trying to instantiate std::tuple<> with as many as 10 template arguments. - Google Test in Visual Studio 2012.

   So, we need to set _VARIADIC_MAX=10 for Preprocessor Definitions under C/C++.
   
   
   
   

   Now, build it again:

   1>------ Rebuild All started: Project: GoogleTest, Configuration: Debug Win32 ------
   1>  gtest_main.cc
   1>  gtest-all.cc
   1>  Generating Code...
   1>  GoogleTest.vcxproj -> c:\users\khyuck\documents\visual studio 2012\Projects\SimpleMath\Debug\GoogleTest.lib
   ========== Rebuild All: 1 succeeded, 0 failed, 0 skipped ==========
     

Now, it's time to create a unit test project.

1. Right click on Solution->Add->New Project with a name unittest_SimpleMath as a Win32 Console. We've just added 3rd prodject to our solution:
   
   
   
   
2. We need to add the two paths as we've done in Step 2:
   Right click on our new project, unittest_SimpleMath.
   On the Properties Pages, add include path:
   C:\GTEST\gtest-1.7.0 and C:\GTEST\gtest-1.7.0\include.
   
   
   
   
3. This project needs additional path to the initial project (SimpleMath) which we want to be tested.
   
   
   
   
4. Let's add new references (GoogleTest and SimpleMath) to unittest_SimpleMath.
   Right click on unittest_SimpleMath->References...
   Under Property Pages->Add New References...
   
   
   
   
   
   
5. Great. Our Unit Test project has been set up.
   Final step will be making a test case.

Now, we need to create a test case.
Type in the following lines of code:

// unittest_SimpleMath.cpp : Defines the entry point for the console application.

#include "gtest/gtest.h"
#include "simplemath.h"

TEST(testMath, myCubeTest)
{
    EXPECT_EQ(1000, cubic(10));	
}