Question

I’m trying to implement unit testing for my code and I’m having a hard time doing it.

Ideally I would like to test some classes not only for good functionality but also for proper memory allocation/deallocation. I wonder if this check can be done using a unit testing framework. I am using Visual Assert btw. I would love to see some sample code , if possible !

Answer 1

You can use the debug functionality right into dev studio to perform leak checking – as long as your unit tests’ run using the debug c-runtime.

A simple example would look something like this:

#include <crtdbg.h>
struct CrtCheckMemory
{
  _CrtMemState state1;
  _CrtMemState state2;
  _CrtMemState state3;
  CrtCheckMemory()
  {
    _CrtMemCheckpoint(&state1);
  }
  ~CrtCheckMemory()
  {
    _CrtMemCheckpoint(&state2);
    // using google test you can just do this.
    EXPECT_EQ(0,_CrtMemDifference( &state3, &state1, &state2));
    // else just do this to dump the leaked blocks to stdout.
    if( _CrtMemDifference( &state3, &state1, &state2) )
      _CrtMemDumpStatistics( &state3 );
  }
};

And to use it in a unit test:

UNIT_TEST(blah)
{
  CrtCheckMemory check;

  // TODO: add the unit test here

}

Some unit test frameworks make their own allocations – Google’s for example allocates blocks when a unit test fails, so any test block that has a fail for any other reason always also has a false positive “leak”.