refs/packed-backend.c: add trace2 counters for jump list

The previous commit added low-level tests to ensure that the packed-refs
iterator did not enumerate excluded sections of the refspace.

However, there was no guarantee that these sections weren't being
visited, only that they were being suppressed from the output. To harden
these tests, add a trace2 counter which tracks the number of regions
skipped by the packed-refs iterator, and assert on its value.

Suggested-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/trace2.h b/trace2.h
index 4ced30c0db..9452e291f5 100644
--- a/trace2.h
+++ b/trace2.h
@@ -551,6 +551,8 @@ enum trace2_counter_id {
 	TRACE2_COUNTER_ID_TEST1 = 0, /* emits summary event only */
 	TRACE2_COUNTER_ID_TEST2,     /* emits summary and thread events */
 
+	TRACE2_COUNTER_ID_PACKED_REFS_JUMPS, /* counts number of jumps */
+
 	/* Add additional counter definitions before here. */
 	TRACE2_NUMBER_OF_COUNTERS
 };