Isolator++

Here's a short example. Let's look at our Product class' method IsExpired:

bool Product::IsExpired()

{

   SYSTEMTIME now;

   ::GetSystemTime(&now);

   if (now.wYear > 2017)

   return true;

   return false;

}

The method has a dependency on the time when the code is run. How can we test the result for a year after 2017?

With Isolator++'s macros (in red), you can simply change the behavior of the GetSystemTime method:

TEST_F(IsolatorPPTests, IsExpired_YearIs2018_ReturnTrue)

{

 Product product;

 // Prepare a future time construct

 SYSTEMTIME fakeTime;

 fakeTime.wYear = 2018;

 // Fake the GetSystemTime method

 FAKE_GLOBAL(GetSystemTime);

 // Replace the returned value when the method is called 

 // with the fake value.

 WHEN_CALLED(GetSystemTime(RET(&fakeTime))).Ignore();

 ASSERT_TRUE(product.IsExpired());

}

When the IsExpired method is called, the call to GetSystemTime is ignored, and then returns the value we supply - our future time construct.

Without changing the code, we actually we able to simulate the GetSystemTime to check a second path in the code.

Isolator++ works with Visual Studio 2005, 2008, 2010, 2012 and 2013 in both 32 and 64 bit.