Subject: Re: [PATCH 8/8] tests: disallow the use of abbreviated options (by default)

From: Denton Liu <[email-masked]>
Date: Mon, 25 Mar 2019 11:35:05 -0700

Hi Johannes,

Thanks for catching this. Perhaps I should've been more diligent and ran
the entire test suite before submitting but I was running low on
batteries only ran the rebase-related tests.

On Mon, Mar 25, 2019 at 11:14:23AM -0700, Johannes Schindelin via GitGitGadget wrote:
> From: Johannes Schindelin <[email-masked]>
> 
> Git's command-line parsers support uniquely abbreviated options, e.g.
> `git init --ba` would automatically expand `--ba` to `--bare`.
> 
> This is a very convenient feature in every day life for Git users, in
> particular when tab completion is not available.
> 
> However, it is not a good idea to rely on that in Git's test suite, as
> something that is a unique abbreviation of a command line option today
> might no longer be a unique abbreviation tomorrow.
> 
> For example, if a future contribution added a new mode
> `git init --babyproofing` and a previously-introduced test case used the
> fact that `git init --ba` expaneded to `git init --bare`, that future

s/expaneded/expanded/

> contribution would now have to touch seemingly unrelated tests just to
> keep the test suite from failing.
> 
> So let's disallow abbreviated options in the test suite by default.
> 
> Note: for ease of implementation, this patch really only touches the
> `parse-options` machinery: more and more hand-rolled option parsers are
> converted to use that internal API, and more and more scripts are
> converted to built-ins (naturally using the parse-options API, too), so
> in practice this catches most issues, and is definitely the biggest bang
> for the buck.
> 
> Signed-off-by: Johannes Schindelin <[email-masked]>
> ---
>  parse-options.c          | 9 +++++++++
>  t/README                 | 4 ++++
>  t/t0040-parse-options.sh | 7 ++++++-
>  t/test-lib.sh            | 6 ++++++
>  4 files changed, 25 insertions(+), 1 deletion(-)
> 
> diff --git a/parse-options.c b/parse-options.c
> index cec74522e5..acc3a93660 100644
> --- a/parse-options.c
> +++ b/parse-options.c
> @@ -6,6 +6,8 @@
>  #include "color.h"
>  #include "utf8.h"
>  
> +static int disallow_abbreviated_options;
> +
>  #define OPT_SHORT 1
>  #define OPT_UNSET 2
>  
> @@ -344,6 +346,10 @@ static enum parse_opt_result parse_long_opt(
>  		return get_value(p, options, all_opts, flags ^ opt_flags);
>  	}
>  
> +	if (disallow_abbreviated_options && (ambiguous_option || abbrev_option))
> +		die("disallowed abbreviated or ambiguous option '%.*s'",
> +		    (int)(arg_end - arg), arg);
> +
>  	if (ambiguous_option) {
>  		error(_("ambiguous option: %s "
>  			"(could be --%s%s or --%s%s)"),
> @@ -708,6 +714,9 @@ int parse_options(int argc, const char **argv, const char *prefix,
>  {
>  	struct parse_opt_ctx_t ctx;
>  
> +	disallow_abbreviated_options =
> +		git_env_bool("GIT_TEST_DISALLOW_ABBREVIATED_OPTIONS", 0);
> +
>  	parse_options_start(&ctx, argc, argv, prefix, options, flags);
>  	switch (parse_options_step(&ctx, options, usagestr)) {
>  	case PARSE_OPT_HELP:
> diff --git a/t/README b/t/README
> index 656288edce..9ed3051a1c 100644
> --- a/t/README
> +++ b/t/README
> @@ -399,6 +399,10 @@ GIT_TEST_SIDEBAND_ALL=<boolean>, when true, overrides the
>  fetch-pack to not request sideband-all (even if the server advertises
>  sideband-all).
>  
> +GIT_TEST_DISALLOW_ABBREVIATED_OPTIONS=<boolean>, when true (which is
> +the default when running tests), errors out when an abbreviated option
> +is used.
> +
>  Naming Tests
>  ------------
>  
> diff --git a/t/t0040-parse-options.sh b/t/t0040-parse-options.sh
> index b8f366c442..5f6a16336d 100755
> --- a/t/t0040-parse-options.sh
> +++ b/t/t0040-parse-options.sh
> @@ -203,20 +203,24 @@ file: (not set)
>  EOF
>  
>  test_expect_success 'unambiguously abbreviated option' '
> +	GIT_TEST_DISALLOW_ABBREVIATED_OPTIONS=false \
>  	test-tool parse-options --int 2 --boolean --no-bo >output 2>output.err &&
>  	test_must_be_empty output.err &&
>  	test_cmp expect output
>  '
>  
>  test_expect_success 'unambiguously abbreviated option with "="' '
> +	GIT_TEST_DISALLOW_ABBREVIATED_OPTIONS=false \
>  	test-tool parse-options --expect="integer: 2" --int=2
>  '
>  
>  test_expect_success 'ambiguously abbreviated option' '
> -	test_expect_code 129 test-tool parse-options --strin 123
> +	test_expect_code 129 env GIT_TEST_DISALLOW_ABBREVIATED_OPTIONS=false \
> +	test-tool parse-options --strin 123
>  '
>  
>  test_expect_success 'non ambiguous option (after two options it abbreviates)' '
> +	GIT_TEST_DISALLOW_ABBREVIATED_OPTIONS=false \
>  	test-tool parse-options --expect="string: 123" --st 123
>  '
>  
> @@ -325,6 +329,7 @@ file: (not set)
>  EOF
>  
>  test_expect_success 'negation of OPT_NONEG flags is not ambiguous' '
> +	GIT_TEST_DISALLOW_ABBREVIATED_OPTIONS=false \
>  	test-tool parse-options --no-ambig >output 2>output.err &&
>  	test_must_be_empty output.err &&
>  	test_cmp expect output

Would it make sense to include a test case to ensure that
GIT_TEST_DISALLOW_ABBREVIATED_OPTIONS is working properly?

Thanks,

Denton

> diff --git a/t/test-lib.sh b/t/test-lib.sh
> index 562c57e685..e550009411 100644
> --- a/t/test-lib.sh
> +++ b/t/test-lib.sh
> @@ -57,6 +57,12 @@ fi
>  . "$GIT_BUILD_DIR"/GIT-BUILD-OPTIONS
>  export PERL_PATH SHELL_PATH
>  
> +# Disallow the use of abbreviated options in the test suite by default
> +test -n "$GIT_TEST_DISALLOW_ABBREVIATED_OPTIONS" || {
> +	GIT_TEST_DISALLOW_ABBREVIATED_OPTIONS=true
> +	export GIT_TEST_DISALLOW_ABBREVIATED_OPTIONS
> +}
> +
>  ################################################################
>  # It appears that people try to run tests without building...
>  "${GIT_TEST_INSTALLED:-$GIT_BUILD_DIR}/git$X" >/dev/null
> -- 
> gitgitgadget