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.