fsmonitor: add a test tool to dump the index extension

Add a test utility (test-dump-fsmonitor) that will dump the fsmonitor
index extension.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -639,6 +639,7 @@ TEST_PROGRAMS_NEED_X += test-config
 TEST_PROGRAMS_NEED_X += test-date
 TEST_PROGRAMS_NEED_X += test-delta
 TEST_PROGRAMS_NEED_X += test-dump-cache-tree
+TEST_PROGRAMS_NEED_X += test-dump-fsmonitor
 TEST_PROGRAMS_NEED_X += test-dump-split-index
 TEST_PROGRAMS_NEED_X += test-dump-untracked-cache
 TEST_PROGRAMS_NEED_X += test-fake-ssh

t/helper/.gitignore

@@ -4,6 +4,7 @@
 /test-date
 /test-delta
 /test-dump-cache-tree
+/test-dump-fsmonitor
 /test-dump-split-index
 /test-dump-untracked-cache
 /test-fake-ssh

t/helper/test-dump-fsmonitor.c

@@ -0,0 +1,21 @@
+#include "cache.h"
+
+int cmd_main(int ac, const char **av)
+{
+	struct index_state *istate = &the_index;
+	int i;
+
+	setup_git_directory();
+	if (do_read_index(istate, get_index_file(), 0) < 0)
+		die("unable to read index file");
+	if (!istate->fsmonitor_last_update) {
+		printf("no fsmonitor\n");
+		return 0;
+	}
+	printf("fsmonitor last update %"PRIuMAX"\n", (uintmax_t)istate->fsmonitor_last_update);
+
+	for (i = 0; i < istate->cache_nr; i++)
+		printf((istate->cache[i]->ce_flags & CE_FSMONITOR_VALID) ? "+" : "-");
+
+	return 0;
+}