Re: [PATCH v3] gdb/testsuite: fix completion tests when using READ1

[Thiago Jung Bauermann <thiago.bauermann@linaro.org>]

Hello Guinevere,

guinevere Larsen via Gdb-patches <gdb-patches@sourceware.org> writes:

> The commit a3da2e7e550c4fe79128b5e532dbb90df4d4f418 has introduced
> regressions when testing using the READ1 mechanism. The reason for that
> is the new failure path in proc test_gdb_complete_tab_unique, which
> looks for GDB suggesting more than what the test inputted, but not the
> correct answer, followed by a white space. Consider the following case:
>
> int foo(int bar, int baz);
>
> Sending the command "break foo<tab>" to GDB will return
>
> break foo(int, int)
>
> which easily fits the buffer in normal testing, so everything works, but
> when reading one character at a time, the test will find the partial
> "break foo(int, " and assume that there was a mistake, so we get a
> spurious FAIL.
>
> That change was added because we wanted to avoid forcing a completion
> failure to fail through timeout, which it had to do because there is no
> way to verify that the output is done, mostly because when I was trying
> to solve a different problem I kept getting reading errors and testing
> completion was frustrating.
>
> This commit implements a better way to avoid that frustration, by first
> testing gdb's complete command and only if that passes we will test tab
> completion. The difference is that when testing with the complete
> command, we can tell when the output is over when we receive the GDB
> prompt again, so we don't need to rely on timeouts. With this, the
> change to test_gdb_complete_tab_unique has been removed as that test
> will only be run and fail in the very unlikely scenario that tab
> completion is different than command completion.
> ---
>  gdb/testsuite/lib/completion-support.exp | 31 +++++++++++++++---------
>  1 file changed, 20 insertions(+), 11 deletions(-)

Great! I was seeing 422 FAILs in gdb.linespec/cpcompletion.exp, and also
1 FAIL in gdb.cp/cpcompletion.exp when using check-read1. With this
patch all tests pass in both testcases, so:

Tested-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>

Also, the code looks good to me:

Reviewed-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>

-- 
Thiago