Re: [PATCH v5 1/3] printf: convert self-test to KUnit

Tamir Duberstein
2025-03-06T14:42:24Z

On Thu, Mar 6, 2025 at 9:25 AM Tamir Duberstein <tamird@gmail.com> wrote:
>
> On Thu, Mar 6, 2025 at 7:25 AM Petr Mladek <pmladek@suse.com> wrote:
> >
> > On Fri 2025-02-21 15:34:30, Tamir Duberstein wrote:
> > > Convert the printf() self-test to a KUnit test.
> > >
> > > [...]
> > >
>
> > 2. What was the motivation to remove the trailing '\n', please?
> >
> > It actually makes a difference from the printk() POV. Messages without
> > the trailing '\n' are _not_ flushed to the console until another
> > message is added. The reason is that they might still be appended
> > by pr_cont(). And printk() emits only complete lines to the
> > console.
> >
> > In general, messages should include the trailing '\n' unless the
> > code wants to append something later or the trailing '\n' is
> > added by another layer of the code. It does not seem to be this case.
> >
> >
> > > bufsize, fmt, ret, elen);
> > > - return 1;
> > > + return;
> > > }
> >
> > [...]
>
> I noticed in my testing that the trailing \n didn't change the test
> output, but I didn't know the details you shared about the trailing
> \n. I'll restore them, unless we jump straight to the KUNIT macros per
> the discussion above.

Ah, I forgot that `tc_fail` already delegates to KUNIT_FAIL. This was
the reason I removed the trailing newlines -- there is a mix of
present and absent trailing newlines in KUNIT_* macros, and it's not
clear to me what the correct thing is. For instance, the examples in
Documentation/dev-tools/kunit/{start,usage}.rst omit the trailing newlines.