Re: Unit testing dissector code

[João Valverde via Wireshark-dev <wireshark-dev () wireshark org>]

Hi Martin,

This is promising. I think dissecting a TVB and walking the proto_tree 
to assert the result is probably the way to go about implementing a 
dissector test suite (instead of reading a pcap with tshark and grepping 
the output).

But regarding your PoC having to give extern linkage to the internal 
dissector code is a big drawback IMO, even if it isn't visible in a DLL 
(because we use default hidden visibility when the compiler supports it).

Maybe that could be solved by including the dissector source file in the 
test source file?

/* test_packet-bt-dht.c */

#include <epan/dissectors/packet-bt-dht.c>

void  test_foo(void)
{...}

int main(void)
{...}

/* end test_packet-bt-dht.c */

Just something to consider. Build time will be slowish with a large test 
suite, but running the test suite should be several orders of magnitude 
faster. And there are no binaries committed to the repo tree for 
dissectors (assuming the TVB data is included as a C array).

BR,

João

On 01/03/21 19:40, Martin Nyhus wrote:
> Hi,
> since the happy-shark discussion died out I've been looking at other
> ways of adding test coverage for some bug fixes I've been preparing to
> push, and right now the idea is to add a new unit test suite based on
> wmem_test for dissector code. I think this should solve the concern that
> was mentioned about build/CI runtime, but I'm not sure how people feel
> about the effect on the source tarballs and the repository.
>
> My attempt at implementing this is merge request 2250 [0], and I've got
> some more tests I'd like to add on a branch in my own fork [1].
>
> I'd like to hear what people think about this approach to testing
> dissector code.
>
> - Martin
>
> [0] https://gitlab.com/wireshark/wireshark/-/merge_requests/2250
> [1]
> https://gitlab.com/zidel_/wireshark/-/commit/e6f4a741599ac162d168497e45452c1379bac23e
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