Does anyone know a way to build DLLs at runtime?

Testing regsvr32.exe requires one or more DLLs, so I compiled a test DLL for use with the tests.

Apparently, the tests should be self-contained, meaning the DLL is produced at run-time. I'm assuming this is done for anyone using the winetest program.

I thought I could write the DLL manually, using IMAGE_NT_HEADERS and other structures. Unfortunately, I'm unable to write the required functions to the file. For one thing, functions have no size.

Another method would be to build the DLL and use the linker to convert the DLL to an object file, link the binary in, and then output it at run-time.

Alternatively, I can leave the tests out of the source tree.

Opinions?