Re: [PATCH] gdb/testsuite: Improve testing of GDB's completion functions

[Bruno Larsen <blarsen@redhat.com>]

On 15/07/2023 14:13, Tom de Vries wrote:
> On 2/22/23 10:11, Bruno Larsen via Gdb-patches wrote:
>> When looking at some failures of gdb.linespec/cp-completion-aliases.exp,
>> I noticed that when a completion test will fail, it always fails with a
>> timeout.  This is because most completion tests use gdb_test_multiple
>> and only add a check for the correct output.  This commit adds new
>> options for both, tab and command completion.
>>
>> For command completion, the new option will check if the prompt was
>> printed, and fail in this case. This is enough to know that the test has
>> failed because the check comes after the PASS path. For tab completion,
>> we have to check if GDB outputted more than just the input line, because
>> sometimes GDB would have printed a partial line before finishing with
>> the correct completion.
>
> This causes quite a few regressions with check-read1.
>
> For instance:
> ...
> (gdb) break baz(int, FAIL: gdb.cp/cpcompletion.exp: tab complete 
> "break baz(int"
> double) Quit^M
> (gdb)
> ...
Hi! Sorry for taking so long to respond. I'd appreciate some help in 
solving, if you have the time.
>
> Thanks,
> - Tom
>
>> ---
>>   gdb/testsuite/lib/completion-support.exp | 16 ++++++++++++++++
>>   1 file changed, 16 insertions(+)
>>
>> diff --git a/gdb/testsuite/lib/completion-support.exp 
>> b/gdb/testsuite/lib/completion-support.exp
>> index bf9c5ad352c..275f8874f15 100644
>> --- a/gdb/testsuite/lib/completion-support.exp
>> +++ b/gdb/testsuite/lib/completion-support.exp
>> @@ -94,6 +94,9 @@ proc test_gdb_complete_tab_none { line } {
>>       -re "^$line_re$completion::bell_re$" {
>>           pass "$test"
>>       }
>> +    -re "$line_re\[^ \]+ $" {
>> +        fail "$test"
>> +    }
>>       }
>>         clear_input_line $test
>> @@ -108,11 +111,15 @@ proc test_gdb_complete_tab_unique { input_line 
>> complete_line_re append_char_re }
>>         set test "tab complete \"$input_line\""
>>       send_gdb "$input_line\t"
>> +    set partial_complete [string_to_regexp $input_line]
>>       set res 1
>>       gdb_test_multiple "" "$test" {
>>       -re "^$complete_line_re$append_char_re$" {
>>           pass "$test"
>>       }
>> +    -re "$partial_complete\[^ \]+ $" {
>> +        fail "$test"
>> +    }

This is the specific change that causes the failures. The thinking 
behind it was that if we receive more characters, but not the whole 
complete_line, we got a failure. Something like this could detect if we 
have a unique - but wrong - suggestion or multiple options. This way it 
doesn't have to go to timeout every time, because it was making clang 
testing take too long.

Is there any other way to detect if GDB is done with the suggestion? Or 
can we detect that read1 is being used, so this gets special cased?

-- 
Cheers,
Bruno

>>       timeout {
>>           fail "$test (timeout)"
>>           set res -1
>> @@ -164,6 +171,9 @@ proc test_gdb_complete_tab_multiple { input_line 
>> add_completed_line \
>>               }
>>               }
>>           }
>> +        -re "${maybe_bell}\r\n.+\r\n$gdb_prompt $" {
>> +            fail "$test"
>> +        }
>>           }
>>       }
>>       }
>> @@ -191,6 +201,9 @@ proc test_gdb_complete_cmd_unique { input_line 
>> complete_line_re } {
>>       -re "^$cmd_re\r\n$complete_line_re\r\n$gdb_prompt $" {
>>           pass $test
>>       }
>> +    -re "$gdb_prompt $" {
>> +        fail "$test"
>> +    }
>>       }
>>   }
>>   @@ -217,6 +230,9 @@ proc test_gdb_complete_cmd_multiple { 
>> cmd_prefix completion_word completion_list
>>       -re "^$cmd_re\r\n$expected_re$gdb_prompt $" {
>>           pass $test
>>       }
>> +    -re "$gdb_prompt $" {
>> +        fail "$test"
>> +    }
>>       }
>>   }
>