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Re: [PATCH v3 2/8] env--helper: new undocumented builtin wrapping git_env_*()

From
Junio C Hamano <gitster@pobox.com>
Date
Jun 21, 2019, 17:07 UTC
Message-ID
<xmqqr27mkgty.fsf@gitster-ct.c.googlers.com>
In-Reply-To
<20190621101812.27300-3-avarab@gmail.com>
Ævar Arnfjörð Bjarmason  <avarab@gmail.com> writes:
Show 5 quoted lines
> The --type=bool option will be used by subsequent patches, but not
> --type=ulong. I figured it was easy enough to add it & test for it so
> I left it in so we'd have wrappers for both git_env_*() functions, and
> to have a template to make it obvious how we'd add --type=int etc. if
> it's needed in the future.

Yup, it is fine to start small/minimal. In addition, obviously we would eventually want "string" type (in fact, it would probably be the reasonable default when --type=<type> option is missing, once this becomes a real command and not a test helper).

> +static char const * const env__helper_usage[] = {
> +	N_("git env--helper --type=[bool|ulong] <options> <env-var>"),

This makes it look as if --type=<type> is not among options, which I am not sure is the impression we would want to give, as I doubt we would want to keep it mandatory in the long run, but I'd say it is OK for two reasons (1) as we start minimal, it is OK to keep this mandatory, and (2) this gives us a place to enumerate available types.

The output from "git env--helper -h" may redundantly list the "--type" option, though.

> +	argc = parse_options(argc, argv, prefix, opts, env__helper_usage,
> +			     PARSE_OPT_KEEP_UNKNOWN);
Why KEEP_UNKNOWN?
Show 17 quoted lines
> +	if (env_default && !*env_default)
> +		usage_with_options(env__helper_usage, opts);
> +	if (!cmdmode)
> +		usage_with_options(env__helper_usage, opts);
> +	if (argc != 1)
> +		usage_with_options(env__helper_usage, opts);
> +	env_variable = argv[0];
> +
> +	switch (cmdmode) {
> +	case ENV_HELPER_TYPE_BOOL:
> +		if (env_default) {
> +			default_int = git_parse_maybe_bool(env_default);
> +			if (default_int == -1) {
> +				error(_("option `--default' expects a boolean value with `--type=bool`, not `%s`"),
> +				      env_default);
> +				usage_with_options(env__helper_usage, opts);
> +			}

OK, that more-or-less is equivalent to what git_config_bool_or_int() does, except that I would say "if (default_int < 0)" to match the original more closely if I were doing this.

Show 8 quoted lines
> +		} else {
> +			default_int = 0;
> +		}
> +		ret_int = git_env_bool(env_variable, default_int);
> +		if (!exit_code)
> +			puts(ret_int ? "true" : "false");
> +		ret = ret_int;
> +		break;

I do not think we want to assign 0 to 'ret' if we are not doing "exit_code". "We successfully found that the variable's value is false, said that to standard output, and signal success by exiting with 0 status" is what we would want, no?

Show 14 quoted lines
> +	case ENV_HELPER_TYPE_ULONG:
> +		if (env_default) {
> +			if (!git_parse_ulong(env_default, &default_ulong)) {
> +				error(_("option `--default' expects an unsigned long value with `--type=ulong`, not `%s`"),
> +				      env_default);
> +				usage_with_options(env__helper_usage, opts);
> +			}
> +		} else {
> +			default_ulong = 0;
> +		}
> +		ret_ulong = git_env_ulong(env_variable, default_ulong);
> +		if (!exit_code)
> +			printf("%lu\n", ret_ulong);
> +		ret = ret_ulong;
Likewise.
Show 44 quoted lines
> +		break;
> +	default:
> +		BUG("unknown <type> value");
> +		break;
> +	}
> +
> +	return !ret;
> +}
> diff --git a/git.c b/git.c
> index c2eec470c9..a43e1dd98e 100644
> --- a/git.c
> +++ b/git.c
> @@ -500,6 +500,7 @@ static struct cmd_struct commands[] = {
>  	{ "diff-index", cmd_diff_index, RUN_SETUP | NO_PARSEOPT },
>  	{ "diff-tree", cmd_diff_tree, RUN_SETUP | NO_PARSEOPT },
>  	{ "difftool", cmd_difftool, RUN_SETUP_GENTLY },
> +	{ "env--helper", cmd_env__helper },
>  	{ "fast-export", cmd_fast_export, RUN_SETUP },
>  	{ "fetch", cmd_fetch, RUN_SETUP },
>  	{ "fetch-pack", cmd_fetch_pack, RUN_SETUP | NO_PARSEOPT },
> diff --git a/t/t0017-env-helper.sh b/t/t0017-env-helper.sh
> new file mode 100755
> index 0000000000..709bbbd275
> --- /dev/null
> +++ b/t/t0017-env-helper.sh
> @@ -0,0 +1,83 @@
> +#!/bin/sh
> +
> +test_description='test env--helper'
> +
> +. ./test-lib.sh
> +
> +
> +test_expect_success 'env--helper usage' '
> +	test_must_fail git env--helper &&
> +	test_must_fail git env--helper --type=bool &&
> +	test_must_fail git env--helper --type=ulong &&
> +	test_must_fail git env--helper --type=bool &&
> +	test_must_fail git env--helper --type=bool --default &&
> +	test_must_fail git env--helper --type=bool --default= &&
> +	test_must_fail git env--helper --defaultxyz
> +'
> +
> +test_expect_success 'env--helper bad default values' '
I think
	sane_unset MISSING &&

is needed, as I do not think test-lib.sh filters that variable from the tester's environment from being seen by us.

> +	test_must_fail git env--helper --type=bool --default=1xyz MISSING &&
> +	test_must_fail git env--helper --type=ulong --default=1xyz MISSING

Both I and you know that the current implementation of env--helper happens to notice and bail for failing to parse --default without even consulting the variable, but we do not have to rely on such an implementation detail.

Speaking of that particular implementation detail, if the variable is not missing, should we even parse and complain what is in --default? I think the answer is "yes, for catching bugs in the script, that is more useful behaviour".

If that is the design principle, we should also test cases where an existing variable is given with a --default that is unparseable and make sure that the command fails.

> +'
> +
> +test_expect_success 'env--helper --type=bool' '
Ditto for sane_unset MISSING upfront.
Show 11 quoted lines
> +	# Test various --default bool values
> +	echo true >expected &&
> +	git env--helper --type=bool --default=1 MISSING >actual &&
> +	test_cmp expected actual &&
> +	git env--helper --type=bool --default=yes MISSING >actual &&
> +	test_cmp expected actual &&
> +	git env--helper --type=bool --default=true MISSING >actual &&
> +	test_cmp expected actual &&
> +	echo false >expected &&
> +	test_must_fail git env--helper --type=bool --default=0 MISSING >actual &&
> +	test_cmp expected actual &&

As I said already, it is a horrible calling convention to make the mode that produces textual output to fail when the variable is set to false. The above two should read more like

    echo true >expect &&
    git env--helper --type=bool --default=true MISSING >actual &&
    test_cmp expect actual &&
    echo false >expect &&
    git env--helper --type=bool --default=0 MISSING >actual &&
    test_cmp expect actual &&
Previous: Ævar Arnfjörð BjarmasonNext: Ævar Arnfjörð Bjarmason
Message 15 of 61 in “fetch: only run 'gc' once when fetching multiple remotes”
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  2. gc: run more pre-detach operations under lockÆvar Arnfjörð Bjarmason, Jun 19, 2019
  3. Duy NguyenJun 19, 2019
  4. Ævar Arnfjörð BjarmasonJun 19, 2019
  5. Jeff KingJun 19, 2019
  6. Ævar Arnfjörð BjarmasonJun 19, 2019
  7. 0/6 Change <non-empty?> GIT_TEST_* variables to <boolean>Ævar Arnfjörð Bjarmason, Jun 19, 2019
  8. Junio C HamanoJun 20, 2019
  9. Ævar Arnfjörð BjarmasonJun 20, 2019
  10. Junio C HamanoJun 20, 2019
  11. 0/8 Change <non-empty?> GIT_TEST_* variables to <boolean>Ævar Arnfjörð Bjarmason, Jun 20, 2019
  12. 1/8 config tests: simplify include cycle testÆvar Arnfjörð Bjarmason, Jun 21, 2019
  13. 0/8 Change <non-empty?> GIT_TEST_* variables to <boolean>Ævar Arnfjörð Bjarmason, Jun 21, 2019
  14. 2/8 env--helper: new undocumented builtin wrapping git_env_*()Ævar Arnfjörð Bjarmason, Jun 21, 2019
  15. Junio C HamanoJun 21, 2019
  16. 3/8 config.c: refactor die_bad_number() to not call gettext() earlyÆvar Arnfjörð Bjarmason, Jun 21, 2019
  17. 4/8 t6040 test: stop using global "script" variableÆvar Arnfjörð Bjarmason, Jun 21, 2019
  18. 6/8 tests README: re-flow a previously changed paragraphÆvar Arnfjörð Bjarmason, Jun 21, 2019
  19. 5/8 tests: make GIT_TEST_GETTEXT_POISON a booleanÆvar Arnfjörð Bjarmason, Jun 21, 2019
  20. Junio C HamanoJun 24, 2019
  21. 7/8 tests: replace test_tristate with "git env--helper"Ævar Arnfjörð Bjarmason, Jun 21, 2019
  22. 1/2 t/lib-git-svn.sh: check GIT_TEST_SVN_HTTPD when running SVN HTTP testsSZEDER Gábor, Sep 6, 2019
  23. 2/2 ci: restore running httpd testsSZEDER Gábor, Sep 6, 2019
  24. Junio C HamanoSep 6, 2019
  25. Jeff KingSep 6, 2019
  26. SZEDER GáborSep 7, 2019
  27. 0/2 tests: catch non-bool GIT_TEST_* valuesSZEDER Gábor, Nov 22, 2019
  28. 1/2 tests: add 'test_bool_env' to catch non-bool GIT_TEST_* valuesSZEDER Gábor, Nov 22, 2019
  29. Jeff KingNov 25, 2019
  30. 2/2 t5608-clone-2gb.sh: turn GIT_TEST_CLONE_2GB into a boolSZEDER Gábor, Nov 22, 2019
  31. Jeff KingNov 25, 2019
  32. 8/8 tests: make GIT_TEST_FAIL_PREREQS a booleanÆvar Arnfjörð Bjarmason, Jun 21, 2019
  33. 1/8 config tests: simplify include cycle testÆvar Arnfjörð Bjarmason, Jun 20, 2019
  34. 2/8 env--helper: new undocumented builtin wrapping git_env_*()Ævar Arnfjörð Bjarmason, Jun 20, 2019
  35. Junio C HamanoJun 20, 2019
  36. Junio C HamanoJun 20, 2019
  37. Ævar Arnfjörð BjarmasonJun 21, 2019
  38. Junio C HamanoJun 21, 2019
  39. 3/8 config.c: refactor die_bad_number() to not call gettext() earlyÆvar Arnfjörð Bjarmason, Jun 20, 2019
  40. 4/8 t6040 test: stop using global "script" variableÆvar Arnfjörð Bjarmason, Jun 20, 2019
  41. 5/8 tests: make GIT_TEST_GETTEXT_POISON a booleanÆvar Arnfjörð Bjarmason, Jun 20, 2019
  42. 7/8 tests: replace test_tristate with "git env--helper"Ævar Arnfjörð Bjarmason, Jun 20, 2019
  43. 6/8 tests README: re-flow a previously changed paragraphÆvar Arnfjörð Bjarmason, Jun 20, 2019
  44. 8/8 tests: make GIT_TEST_FAIL_PREREQS a booleanÆvar Arnfjörð Bjarmason, Jun 20, 2019
  45. 1/6 env--helper: new undocumented builtin wrapping git_env_*()Ævar Arnfjörð Bjarmason, Jun 19, 2019
  46. Junio C HamanoJun 20, 2019
  47. 2/6 t6040 test: stop using global "script" variableÆvar Arnfjörð Bjarmason, Jun 19, 2019
  48. Junio C HamanoJun 20, 2019
  49. 3/6 tests: make GIT_TEST_GETTEXT_POISON a booleanÆvar Arnfjörð Bjarmason, Jun 19, 2019
  50. Junio C HamanoJun 20, 2019
  51. 5/6 tests: replace test_tristate with "git env--helper"Ævar Arnfjörð Bjarmason, Jun 19, 2019
  52. 4/6 tests README: re-flow a previously changed paragraphÆvar Arnfjörð Bjarmason, Jun 19, 2019
  53. 6/6 tests: make GIT_TEST_FAIL_PREREQS a booleanÆvar Arnfjörð Bjarmason, Jun 19, 2019
  54. Duy NguyenJun 20, 2019
  55. Ævar Arnfjörð BjarmasonJun 20, 2019
  56. Jeff KingJun 20, 2019
  57. Junio C HamanoJun 20, 2019
  58. Jeff KingJun 19, 2019
  59. Jeff KingJun 19, 2019
  60. Duy NguyenJun 20, 2019
  61. Jeff KingJun 20, 2019

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