Re: [PATCH v2 4/5] Add `human` format to test-tool

[Junio C Hamano <gitster@pobox.com>]

"Stephen P. Smith" <ischis2@cox.net> writes:

> Add the human format support to the test tool so that TEST_DATE_NOW
> can be used to specify the current time.
>
> A static variable is used for passing the tool specified value to
> get_date.  The get_date helper function eliminates the need to
> refactor up the show_date and show_date normal functions to pass the
> time value.

Hmph.  An interesting approach, but the implementation is a bit too
messy.

> diff --git a/date.c b/date.c
> index 43c3a84e25..24435b1e1d 100644
> --- a/date.c
> +++ b/date.c
> @@ -115,6 +115,28 @@ static int local_tzoffset(timestamp_t time)
>  	return local_time_tzoffset((time_t)time, &tm);
>  }
>  
> +const struct timeval *test_time = 0;

Shouldn't this be file-scope static?

Let BSS take care of initializing a variable to 0/NULL; drop " = 0"
at the end.

> +void show_date_human(timestamp_t time, int tz,
> +			       const struct timeval *now,
> +			       struct strbuf *timebuf)
> +{
> +	test_time = (const struct timeval *) now;
> +	strbuf_addstr( timebuf, show_date(time, tz, DATE_MODE(HUMAN)));

Style:
	strbuf_addstr(timebuf, show_date(time, tz, DATE_MODE(HUMAN)));

> +	test_time = (const struct timeval *) 0;
> +}

It is a shame that you introduced a nicely reusable get_time()
mechanism to let external callers of show_date() specify what time
to format, instead of the returned timestamp of gettimeofday(),
but limited its usefulness to only testing "human" format output.
If somebody wants to extend "test-tool date" for other formats, they
also have to add a similar "show_date_XXX" hack for their format.

How about doing it slightly differently?  E.g.

 - Get rid of show_date_human().

 - Keep get_time(), but have it pay attention to GIT_TEST_TIMESTAMP
   environment variable, and when it is set, use that as if it is
   the returned value from gettimeofday().

 - If there are gettimeofday() calls in date.c this patch did not
   touch (because they were not part of the "human-format"
   codepath), adjust them to use get_time() instead.

 - Have "test-tool date" excersize show_date() directly. 



> +static void get_time(struct timeval *now)
> +{
> +	if(test_time != 0)
> +		/*
> +		 * If show_date was called via the test
> +		 *  interface use the test_tool time
> +		 */
> +		*now = *test_time;
> +	else
> +		gettimeofday(now, NULL);
> +}
> +
>  void show_date_relative(timestamp_t time, int tz,
>  			       const struct timeval *now,
>  			       struct strbuf *timebuf)
> @@ -228,7 +250,7 @@ static void show_date_normal(struct strbuf *buf, timestamp_t time, struct tm *tm
>  	/* Show "today" times as just relative times */
>  	if (hide.wday) {
>  		struct timeval now;
> -		gettimeofday(&now, NULL);
> +		get_time(&now);
>  		show_date_relative(time, tz, &now, buf);
>  		return;
>  	}
> @@ -284,7 +306,7 @@ const char *show_date(timestamp_t time, int tz, const struct date_mode *mode)
>  	if (mode->type == DATE_HUMAN) {
>  		struct timeval now;
>  
> -		gettimeofday(&now, NULL);
> +		get_time(&now);
>  
>  		/* Fill in the data for "current time" in human_tz and human_tm */
>  		human_tz = local_time_tzoffset(now.tv_sec, &human_tm);
> diff --git a/t/helper/test-date.c b/t/helper/test-date.c
> index a0837371ab..22d42a2174 100644
> --- a/t/helper/test-date.c
> +++ b/t/helper/test-date.c
> @@ -3,6 +3,7 @@
>  
>  static const char *usage_msg = "\n"
>  "  test-tool date relative [time_t]...\n"
> +"  test-tool date human [time_t]...\n"
>  "  test-tool date show:<format> [time_t]...\n"
>  "  test-tool date parse [date]...\n"
>  "  test-tool date approxidate [date]...\n"
> @@ -22,6 +23,18 @@ static void show_relative_dates(const char **argv, struct timeval *now)
>  	strbuf_release(&buf);
>  }
>  
> +static void show_human_dates(const char **argv, struct timeval *now)
> +{
> +	struct strbuf buf = STRBUF_INIT;
> +
> +	for (; *argv; argv++) {
> +		time_t t = atoi(*argv);
> +		show_date_human(t, 0, now, &buf);
> +		printf("%s -> %s\n", *argv, buf.buf);
> +	}
> +	strbuf_release(&buf);
> +}
> +
>  static void show_dates(const char **argv, const char *format)
>  {
>  	struct date_mode mode;
> @@ -100,6 +113,8 @@ int cmd__date(int argc, const char **argv)
>  		usage(usage_msg);
>  	if (!strcmp(*argv, "relative"))
>  		show_relative_dates(argv+1, &now);
> +	else if (!strcmp(*argv, "human"))
> +		show_human_dates(argv+1, &now);
>  	else if (skip_prefix(*argv, "show:", &x))
>  		show_dates(argv+1, x);
>  	else if (!strcmp(*argv, "parse"))