From: Andrei Rybak <rybak.a.v@gmail.com>
Date: Thu, 24 Jun 2021 19:23:14 GMT
Subject: Re: [PATCH v3 1/4] test-lib-functions: introduce test_line_count_cmd
Message-ID: <6ad6ac5a-18ac-102e-29dc-3c0987de08e7@gmail.com>
In-Reply-To: <54bf7756-5578-4fe4-dbe5-f63b368c4d63@gmail.com>

On 21/06/2021 11:08, Andrei Rybak wrote:
> On 19/06/2021 03:30, Đoàn Trần Công Danh wrote:
>> diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
>> index f0448daa74..e055a4f808 100644
>> --- a/t/test-lib-functions.sh
>> +++ b/t/test-lib-functions.sh
>> @@ -845,6 +845,86 @@ test_line_count () {
>>       fi
>>   }
>> +# test_line_count_cmd checks the exit status, and the number of lines in
>> +# the captured stdout of a command.
>> +#
>> +# SYNOPSIS:
>> +#
>> +#    test_line_count_cmd <binop> <value> [!] cmd [args...]
>> +#
>> +# Expect succeed exit status when running
>> +#
>> +#    cmd [args...]
>> +#
>> +# then, run sh's "test <# of lines in stdout> <binop> <value>"
>> +#
>> +# OPTIONS:
>> +# !:
>> +#    Instead of expecting "cmd [args...]" succeed, expect its failure.
>> +#    Note, if the command under testing is "git",
>> +#    test_must_fail should be used instead of "!".
>> +#
>> +# EXAMPLE:
>> +#    test_line_count_cmd -ge 10 git tag --no-contains v1.0.0
>> +#    test_line_count_cmd -le 10 ! grep some-text a-file
>> +#    test_line_count_cmd = 0 test_must_fail git rev-parse --verify 
>> abcd1234
>> +#
>> +# NOTE:
>> +# * a temporary file named test_line_count_cmd_.out will be created 
>> under
>> +# $TRASH_DIRECTORY/.git/trash iff $TRASH_DIRECTORY/.git/ exists.
>> +# Otherwise, created in $TRASH_DIRECTORY. This temporary file will be
>> +# cleaned by test_when_finished
>> +test_line_count_cmd () {
>> +    {
>> +        local outop outval outfile
>> +        local expect_failure actual_failure
>> +        local trashdir="$TRASH_DIRECTORY"
>> +
>> +        if test -d "$TRASH_DIRECTORY/.git"
>> +        then
>> +            trashdir="$TRASH_DIRECTORY/.git/trash" &&
>> +            mkdir -p "$trashdir"
>> +        fi &&
>> +        if test $# -lt 3
>> +        then
>> +            BUG "missing <binary-ops> and <value>"
> 
> Nit: s/binary-ops/binop/ for consistency with documentation comment
> above.  Also, technically the invocation of test_line_count_cmd could be
> missing any of its required three parameters, including "cmd".  How
> about something similar to the call to BUG in test_i18ngrep:
> 
>      BUG "too few parameters to test_line_count_cmd"
> 
> ?
> 
>> +        fi &&
>> +        outop="$1" &&
>> +        outval="$2" &&
>> +        shift 2 &&
>> +        outfile="$trashdir/test_line_count_cmd_.out" &&
>> +        if test "x$1" = "x!"
>> +        then
>> +            shift &&
>> +            expect_failure=yes
>> +        fi &&
>> +        if test $# = 0
>> +        then
>> +            BUG "test_line_count_cmd: no command to be run"
>> +        else
>> +            test_when_finished "rm -f '$outfile'" &&
>> +            exec 8>"$outfile"
>> +            # We need to redirect stderr to &9,
>> +            # and redirect this function's 9>&2
>> +            # in order to not messed with -x
>> +            if ! "$@" >&8 2>&9
>> +            then
>> +                actual_failure=yes
>> +            fi
>> +        fi 8>&1 &&
>> +        case "$expect_failure,$actual_failure" in
>> +        yes,)
>> +            echo >&4 "error: '$@' succeed!" &&
> 
> It seems that function error() could be used here and below instead of
> "echo >&4".

After spending some time reading t/test-lib-functions.sh, now I don't
think that using error() is a good suggestion.  Closest relatives of
test_line_count_cmd -- test_line_count and test_must_be_empty -- both
just use "echo".  Other usages of error() in t/test-lib.sh and
t/test-lib-functions.sh suggest that error() is not meant to be used
for reporting test failure messages, but internal failures. For example:

	error "You haven't built things yet, have you?"

and

	error "Internal error: $stderr disappeared."

> s/succeed/succeeded/ --- it might be worth borrowing wording from
> test_must_fail().  Something like:
> 
>      error "test_line_count_cmd: command succeeded: '$@'"