Over the last few days, I’ve been adapting an existing native C++ library so that it can be called from managed code. I had written a large number of unit tests with CppUnit and I wanted to be able to call the tests from NUnit.

I suppose that I could have written a new CppUnit TestRunner so that I could call it from NUnit. Instead, I took the cheap-n-dirty route, playing with #define and include paths. It took less time to get working than it did to write this blog post.

Here’s the original native CppUnit test code

//-------------------------------
// native\FooTest.h
//-------------------------------

#include <cppunit/extensions/HelperMacros.h>

class FooTest : public CppUnit::TestFixture
{
    CPPUNIT_TEST_SUITE( FooTest );
    CPPUNIT_TEST( testAlpha );
    CPPUNIT_TEST_SUITE_END();
public:
    void testAlpha();
};


//-------------------------------
// native\FooTest.cpp
//-------------------------------

#include "FooTest.h"

// Registers the fixture into the test 'registry'
CPPUNIT_TEST_SUITE_REGISTRATION( FooTest );

void FooTest::testAlpha()
{
    CPPUNIT_ASSERT( 4 == 2 + 2);
}

And here’s my managed NUnit-based wrapper.

//-------------------------------
// managed\FooTest.h
//-------------------------------

using namespace NUnit::Framework;

// Gross hack. Define a completely different NUnit-compatible FooTest
// test fixture and use #define's to make the CPPUnit-specific
// stuff build.

[TestFixture]
public ref class FooTest
{
public:
    [Test] void testAlpha();
};

#define CPPUNIT_TEST_SUITE_REGISTRATION(x)
#define CPPUNIT_ASSERT(x) Assert::IsTrue(x)

I had to make one change to na­tive\­FooTest.cpp, to #include <FooTest.h> (angle brackets). This picks up the first FooTest.h in the include path, so that the managed version of FooTest.cpp now picks up man­aged\­FooTest.h, instead of the original.