Re: exit status codes semantics in tests

[Guy Harris <gharris () sonic net>]

On Oct 16, 2026, at 2:05 PM, Denis Ovsienko <denis () ovsienko info> wrote:

> On Fri, 16 Oct 2026 10:36:49 -0700
> Guy Harris <gharris () sonic net> wrote:

        ...

> If TESTrun has received EX_USAGE from a test program, it means a bug in
> TESTrun because every command line is an internal product of TESTrun.

I.e, EX_USAGE should not be used for any cases where a command-line argument is *intentionallY* made incorrect in 
TESTrun because the program is being used to test to make sure that a particular argument fails - whether it's an 
invalid filter expression for the particular link-layer type (or for *any* link-layer type), or to make sure that an 
invalid string name for a link-layer type returns -1 from pcap_datalink_name_to_val(), or....

> Time stamps in filter apply tests have been discussed once or twice
> before, this could use a command-line option.  Other packet meta-data
> could use the same or other options.  To make complete sense, this
> would need meaningful savefiles and meaningful test definitions to
> exercise specific code paths.

filtertest is a program for testing filters, not to test capture-file reading code; giving it the responsibility for 
the latter would make it even *more* convoluted. I'm working on a *separate* program for that.

Unless there are filter expressions that check the packet arrival time, there's no need for the filter tests to care 
about it.

> For packet data it is not clear what code path it would test.

The code paths that reads pcap and that read pcapng files and produce a struct pcap_pkthdr and a lump of packet data.

> Yes, filter expressions can and in the TESTrun case do come from a
> temporary file.  What matters is that sometimes the result of a test
> must be conveyed as "could not run the test at all", not "test passed"
> or "test failed".

With EIO, ETIMEDOUT, and possibly other read errors being "could not run the test at all".
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