Re: [PATCH v8 3/7] progress.c tests: make start/stop commands on stdin

Change the usage of the "test-tool progress" introduced in
2bb74b53a49 (Test the progress display, 2019-09-16) to take command
like "start" and "stop" on stdin, instead of running them implicitly.

This makes for tests that are easier to read, since the recipe will
mirror the API usage, and allows for easily testing invalid usage that
would yield (or should yield) a BUG(), e.g. providing two "start"
calls in a row. A subsequent commit will add such tests.

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 t/helper/test-progress.c    | 46 ++++++++++++++++++++++-------
 t/t0500-progress-display.sh | 58 +++++++++++++++++++++++--------------
 2 files changed, 72 insertions(+), 32 deletions(-)

diff --git a/t/helper/test-progress.c b/t/helper/test-progress.c
index 50fd3be3dad..becc163375f 100644
--- a/t/helper/test-progress.c
+++ b/t/helper/test-progress.c

@@ -3,6 +3,9 @@
  *
  * Reads instructions from standard input, one instruction per line:
  *
+ *   "start <total>[ <title>]" - Call start_progress(title, total),
+ *                               Uses the default title of "Working hard"
+ *                               if the " <title>" is omitted.
  *   "progress <items>" - Call display_progress() with the given item count
  *                        as parameter.
  *   "throughput <bytes> <millis> - Call display_throughput() with the given

@@ -10,6 +13,7 @@
  *                                  specify the time elapsed since the
  *                                  start_progress() call.
  *   "update" - Set the 'progress_update' flag.
+ *   "stop" - Call stop_progress().
  *
  * See 't0500-progress-display.sh' for examples.
  */

@@ -19,34 +23,52 @@
 #include "parse-options.h"
 #include "progress.h"
 #include "strbuf.h"
+#include "string-list.h"
 
 int cmd__progress(int argc, const char **argv)
 {
-	int total = 0;
-	const char *title;
+	const char *const default_title = "Working hard";
+	struct string_list titles = STRING_LIST_INIT_DUP;
 	struct strbuf line = STRBUF_INIT;
-	struct progress *progress;
+	struct progress *progress = NULL;
 
 	const char *usage[] = {
-		"test-tool progress [--total=<n>] <progress-title>",
+		"test-tool progress <stdin",
 		NULL
 	};
 	struct option options[] = {
-		OPT_INTEGER(0, "total", &total, "total number of items"),
 		OPT_END(),
 	};
 
 	argc = parse_options(argc, argv, NULL, options, usage, 0);
-	if (argc != 1)
-		die("need a title for the progress output");
-	title = argv[0];
+	if (argc)
+		usage_with_options(usage, options);
 
 	progress_testing = 1;
-	progress = start_progress(title, total);
 	while (strbuf_getline(&line, stdin) != EOF) {
 		char *end;
 
-		if (skip_prefix(line.buf, "progress ", (const char **) &end)) {
+		if (skip_prefix(line.buf, "start ", (const char **) &end)) {
+			uint64_t total = strtoull(end, &end, 10);
+			const char *title;
+			const char *str;
+
+			/*
+			 * We can't use "end + 1" as an argument to
+			 * start_progress(), it doesn't xstrdup() its
+			 * "title" argument. We need to hold onto a
+			 * valid "char *" for it until the end.
+			 */
+			if (!*end)
+				title = default_title;
+			else if (*end == ' ')
+				title = string_list_insert(&titles, end + 1)->string;
+			else
+				die("invalid input: '%s'\n", line.buf);
+
+			str = title ? title : default_title;

+			progress = start_progress(str, total);
+		} else if (skip_prefix(line.buf, "progress ", (const char **) &end)) {
 			uint64_t item_count = strtoull(end, &end, 10);
 			if (*end != '\0')
 				die("invalid input: '%s'\n", line.buf);