Testing implementation over interface - c++

Question

I'm starting with test coverage for my C++ project and it was oddness for me, that a lot of frameworks cannot create parametrized unit test.
For example I have interface:
class IBuffer {
public:
virtual void pushBytes(void *data, int length) = 0;
virtual int getSize() = 0;
};
And a few implementors :
class BufferImplOne{};
class BufferImplTwo{};
Now I want to check that pushing bytes to buffer will really increment its size:
TEST_CASE("example/test", "Test for any IBuffer implementor") {
IBuffer *buf = // ... {I want external parameter to be here}
REQUIRE( buf->getSize() == 0 );
int dataLength = 10;
int data[dataLength];
buf->pushBytes(data, dataLength * sizeof(int));
REQUIRE( buf->getSize() == dataLength * sizeof(int));
}
Now I'm gonna to test each implementation, and first thing I want to do - is to check if implementor meets interface tests. But I don't want to copypaste the same code twice, I just want to pass implementation as a parameter to interface test. How to deal with such problem?
I am using CATCH, but seems like other framework don't provide same functionality too.
Anyway I am newcomer in unit testing and maybe I misunderstood something basic?

Answer 1

Something like this:
void TestBuffer(IBuffer& buf)
{
REQUIRE( buf.getSize() == 0 );
int dataLength = 10;
int data[dataLength];
buf.pushBytes(data, dataLength * sizeof(int));
REQUIRE( buf.getSize() == dataLength * sizeof(int));
}
TEST_CASE("example/test", "Test for BufferImplOne implementor")
{
BufferImplOne one;
TestBuffer(one);
}
TEST_CASE("example/test", "Test for BufferImplTwo implementor")
{
BufferImplTwo two;
TestBuffer(two);
}

Answer 2

Well, it's bona fide polymorphism.
void test(IBuffer& ib) {
// ... your tests here ...
}
int main() {
BufferImplOne one;
test(one);
BufferImplTwo two;
test(two);
}
I don't quite see what a framework could provide...