How to free up a resource used by a function in a googletest ASSERT_THROW statement?

Question

In googletest you can use ASSERT_THROW to test that a certain function throws an error. For instance

ASSERT_THROW(PhysicalPropertyResource p("other/identifier72652"), InappropriateResourceException);

How would you explicitely call another method for releasing some memory used by PhysicalPropertyResource? Normally used like so:

PhysicalPropertyResource p("other/identifier72652");
p.free();

Or should I just not worry about the memory leak since its only in a test and therefore benign. (Its just my OCD to want to keep valgrind completly happy).

I've tried this:

    ASSERT_THROW(
            PhysicalPropertyResource p("other/identifier72652");
            p.free();
            , InappropriateResourceException);

}

which doesn't free the memory.

Why doesn't `PhysicalPropertyResource` release resources in its destructor? — Yksisarvinen, Jun 03 '20 at 10:04
This is deliberate. I'm using a C library and this necessitates that I sometimes free some resources manually. — CiaranWelsh, Jun 03 '20 at 10:37

score 0 · Accepted Answer · answered Jun 03 '20 at 11:38

The proper syntax for executing multiple instructions would to wrap them in a block:

ASSERT_THROW({PhysicalPropertyResource p("other/identifier72652");
              p.free();}, 
            InappropriateResourceException);

However, this won't help it's not the last line that throws, because then p.free() will not be called. You could create your own "assertion"

void shouldThrow() {
    std::unique_ptr<PhysicalPropertyResource> p;
    try {
        p = std::make_unique<PhysicalPropertyResource>("other/identifier72652");
    } catch (const InappropriateResourceException&) {
        if (p) //note that this is not possible if it is really constructor that throws
            p->free(); 
        return; //test succeeded
    } catch (...) {
        if (p)
            p->free();
        FAIL();
    }

    if (p)
        p->free;
    FAIL();
}

Note: If you are writing C++ code that uses C library, then your best solution is creation of a RAII wrapper that will take care of resources. If you create a wrapper class, it can free resources in destructor and you will never leak them. You can even write such wrapper for unit tests only, just to avoid this ugly assertion-like code.

Thanks for the response... also I am using a RAII wrapper, there were [complications](https://stackoverflow.com/questions/62109576/how-to-resolve-memory-related-errors-that-arise-from-interaction-between-c-objec/62110107?noredirect=1#comment109860320_62110107) — CiaranWelsh, Jun 03 '20 at 21:37

How to free up a resource used by a function in a googletest ASSERT_THROW statement?

1 Answers1