Have a mode that crashes on all panics

[jakubadamw]

So with #6 and #7 merged in rutenspitz no longer crashes in a fuzz cycle on a panic when both the implementation and the model panic in accordance. This change in behaviour is fine, since the main purpose of this crate is to observe the equivalence of two models. But I think it may be useful to use it also to find panics on malformed input (well, a series of operations to a model). This is exactly what the url::Url fuzzer did, although it did in a rather convoluted way by using url::Url as the supposed doppelganger of url::Url itself.

Rather than doing that we should have a mode which turns off all comparisons, essentially always using

rutenspitz/lib/src/lib.rs

Lines 482 to 486 in ff2c1b2

	pub fn execute(self, tested: &mut #tested) {
	match &self {
	#(#method_tests),*
	}
	}

for individual operation tests, without using (and requiring) a reference model at all.

This is perhaps somewhat out of scope given the name of this crate but nonetheless seems like a useful extension.

[Shnatsel]

This sounds like a "don't compare, just fuzz" mode to me. Several people including myself attempted implementing that independently, see https://github.com/Eh2406/auto-fuzz-test

But that's just a PoC, so it didn't use any proc macros, just filling in values in a template.

[Shnatsel]

You know, a mode without comparison to a reference model, but also without considering panics as failures would indeed be very useful. For example, it would have found CVE-2018-1000810 if run on std::String