Unit test that a class is non copyable, and other compile-time properties

Question

Is there a way to test compile-time errors, but without actually generating the error? For example, if I create a class which is non-copyable, I\'d like to test the fact tha

Answer 1

You can do it using make. Each test will be a code snippet. Here's a working example with 2 tests for VC++. (I've used 2 batch files for pass test and fail test). I'm using GNU make here.

Makefile:

FAILTEST = .\failtest.bat
PASSTEST = .\passtest.bat

tests: must_fail_but_passes \
    must_pass_but_fails

must_fail_but_passes:
    @$(FAILTEST) $@.cpp

must_pass_but_fails:
    @$(PASSTEST) $@.cpp

must_pass_but_fails.cpp

struct Foo {
    int value_;
    Foo(void) : value_(0) {}
  private:
    Foo(const Foo&);
    const Foo& operator=(const Foo&);
};


int main()
{
    Foo f(12);
    return 0;
}

must_fail_but_passes.cpp

struct Foo {
    int value_;
    Foo(int value) : value_(value) {}
  private:
    Foo(const Foo&);
    const Foo& operator=(const Foo&);
};


int main()
{
    Foo f(12);
    return 0;
}

passtest.bat

@echo off
cl /nologo %1 >NUL
if %errorlevel% == 0 goto pass
@echo %1 FAILED
:pass

failtest.bat

@echo off
cl /nologo %1 >NUL
if not %errorlevel% == 0 goto pass
@echo %1 FAILED
:pass

Note that cl.exe (i.e. Visual Studio compiler) need to be in your path for this to "just work"

Have fun!

P.S. I doubt that this would make me famous though :-)