From 49369d8290c3a5c95d835df85fdf53eba7562496 Mon Sep 17 00:00:00 2001
From: Taylor Blau <me@ttaylorr.com>
Date: Mon, 11 May 2026 20:46:51 -0400
Subject: [PATCH] t5333: demonstrate various pseudo-merge bugs

Using the test helper introduced via the previous commit, add various
failing tests demonstrating bugs in the pseudo-merge implementation.

These are all marked as failing with one exception. The "sampleRate=0"
test describes a latent bug, which is only reachable through a code path
that is itself masked by a separate bug. A future commit will fix that
bug, and, in turn, cause the aforementioned test to fail. Accordingly,
that commit will mark the test as failing, and it will be re-marked as
passing in a separate commit which fixes the once-latent bug.

For the rest: the following commits will explain and fix the underlying
bugs in detail.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 t/t5333-pseudo-merge-bitmaps.sh | 198 ++++++++++++++++++++++++++++++++
 1 file changed, 198 insertions(+)

diff --git a/t/t5333-pseudo-merge-bitmaps.sh b/t/t5333-pseudo-merge-bitmaps.sh
index 1f7a5d82ee..0e9638c31c 100755
--- a/t/t5333-pseudo-merge-bitmaps.sh
+++ b/t/t5333-pseudo-merge-bitmaps.sh
@@ -462,4 +462,202 @@ test_expect_success 'use pseudo-merge in boundary traversal' '
 	)
 '
 
+test_expect_failure 'apply pseudo-merges during fill-in traversal' '
+	test_when_finished "rm -fr pseudo-merge-fill-in-traversal" &&
+	git init pseudo-merge-fill-in-traversal &&
+	(
+		cd pseudo-merge-fill-in-traversal &&
+
+		git config bitmapPseudoMerge.test.pattern refs/tags/ &&
+		git config bitmapPseudoMerge.test.maxMerges 1 &&
+		git config bitmapPseudoMerge.test.stableThreshold never &&
+
+		test_commit_bulk 64 &&
+		tag_everything &&
+		git repack -ad &&
+
+		pack=$(ls .git/objects/pack/pack-*.pack) &&
+		git rev-parse HEAD~63 >in &&
+		test-tool bitmap write "$(basename $pack)" <in &&
+
+		test_pseudo_merges >merges &&
+		test_line_count = 1 merges &&
+
+		test_commit stale &&
+
+		git rev-list --count --objects HEAD >expect &&
+
+		: >trace2.txt &&
+		GIT_TRACE2_EVENT=$PWD/trace2.txt \
+			git rev-list --count --objects --use-bitmap-index HEAD >actual &&
+		test_pseudo_merges_satisfied 1 <trace2.txt &&
+
+		test_cmp expect actual
+	)
+'
+
+test_expect_failure 'apply pseudo-merges from multiple groups during fill-in' '
+	test_when_finished "rm -fr pseudo-merge-fill-in-multi" &&
+	git init pseudo-merge-fill-in-multi &&
+	(
+		cd pseudo-merge-fill-in-multi &&
+
+		test_commit base &&
+		base=$(git rev-parse HEAD) &&
+
+		for side in left right
+		do
+			git checkout -B $side base &&
+
+			test_commit_bulk --id=$side 64 &&
+			git rev-list --no-object-names HEAD --not $base >in &&
+			while read oid
+			do
+				echo "create refs/group-$side/$oid $oid" || return 1
+			done <in | git update-ref --stdin || return 1
+		done &&
+
+		git checkout left &&
+		git merge right &&
+		git repack -ad &&
+
+		git config bitmapPseudoMerge.left.pattern "refs/group-left/" &&
+		git config bitmapPseudoMerge.left.maxMerges 1 &&
+		git config bitmapPseudoMerge.left.stableThreshold never &&
+
+		git config bitmapPseudoMerge.right.pattern "refs/group-right/" &&
+		git config bitmapPseudoMerge.right.maxMerges 1 &&
+		git config bitmapPseudoMerge.right.stableThreshold never &&
+
+		pack="$(ls .git/objects/pack/pack-*.pack)" &&
+		git rev-parse "$base" >in &&
+		test-tool bitmap write "$(basename $pack)" <in &&
+
+		test_pseudo_merges >merges &&
+		test_line_count = 2 merges &&
+
+		test_commit stale &&
+
+		git rev-list --count --objects HEAD >expect &&
+
+		: >trace2.txt &&
+		GIT_TRACE2_EVENT=$PWD/trace2.txt \
+			git rev-list --count --objects --use-bitmap-index HEAD >actual &&
+		test_pseudo_merges_satisfied 2 <trace2.txt &&
+
+		test_cmp expect actual
+	)
+'
+
+test_expect_failure 'apply pseudo-merges with overlapping groups during fill-in' '
+	test_when_finished "rm -fr pseudo-merge-fill-in-overlap" &&
+	git init pseudo-merge-fill-in-overlap &&
+	(
+		cd pseudo-merge-fill-in-overlap &&
+
+		test_commit_bulk 64 &&
+		tag_everything &&
+		git repack -ad &&
+
+		pack="$(ls .git/objects/pack/pack-*.pack)" &&
+
+		# Use two pseudo-merge group patterns that both match
+		# refs/tags/, so every tagged commit belongs to both
+		# groups. This exercises the extended lookup table
+		# path in apply_pseudo_merges_for_commit().
+		git config bitmapPseudoMerge.all.pattern "refs/tags/" &&
+		git config bitmapPseudoMerge.all.maxMerges 1 &&
+		git config bitmapPseudoMerge.all.stableThreshold never &&
+
+		git config bitmapPseudoMerge.tags.pattern "refs/tags/" &&
+		git config bitmapPseudoMerge.tags.maxMerges 1 &&
+		git config bitmapPseudoMerge.tags.stableThreshold never &&
+
+		git rev-parse HEAD~63 >in &&
+		test-tool bitmap write "$(basename $pack)" <in &&
+
+		test_pseudo_merges >merges &&
+		test_line_count = 2 merges &&
+
+		test_commit stale &&
+
+		git rev-list --count --objects HEAD >expect &&
+
+		: >trace2.txt &&
+		GIT_TRACE2_EVENT=$PWD/trace2.txt \
+			git rev-list --count --objects --use-bitmap-index HEAD >actual &&
+		test_pseudo_merges_satisfied 2 <trace2.txt &&
+
+		test_cmp expect actual
+	)
+'
+
+test_expect_failure 'pseudo-merge commits are correctly classified by date' '
+	test_when_finished "rm -fr pseudo-merge-date-classification" &&
+	git init pseudo-merge-date-classification &&
+	(
+		cd pseudo-merge-date-classification &&
+
+		test_commit_bulk 64 &&
+		tag_everything &&
+		git repack -ad &&
+
+		pack="$(ls .git/objects/pack/pack-*.pack)" &&
+
+		# Configure two pseudo-merge groups: one that only
+		# matches "stable" refs (older than one month), and one
+		# that matches all refs. With 64 freshly-created tags
+		# (all younger than one month) the stable group should
+		# have zero pseudo-merges and the catch-all group should
+		# have one.
+		#
+		# Use GIT_TEST_DATE_NOW to align "now" (and therefore
+		# "1.month.ago") with the test_tick timestamps so that
+		# the commits are within the last month.
+		#
+		# This exercises the date-based classification in
+		# find_pseudo_merge_group_for_ref(), which requires
+		# that commits are parsed before inspecting their date.
+		git config bitmapPseudoMerge.stable.pattern "refs/tags/" &&
+		git config bitmapPseudoMerge.stable.maxMerges 64 &&
+		git config bitmapPseudoMerge.stable.stableThreshold never &&
+		git config bitmapPseudoMerge.stable.threshold 1.month.ago &&
+
+		git config bitmapPseudoMerge.all.pattern "refs/tags/" &&
+		git config bitmapPseudoMerge.all.maxMerges 1 &&
+		git config bitmapPseudoMerge.all.stableThreshold never &&
+		git config bitmapPseudoMerge.all.threshold now &&
+
+		git rev-parse HEAD~63 >in &&
+		GIT_TEST_DATE_NOW=$test_tick \
+			test-tool bitmap write "$(basename $pack)" <in &&
+
+		test_pseudo_merges >merges &&
+		test_line_count = 1 merges
+	)
+'
+
+test_expect_success 'sampleRate=0 does not cause division by zero' '
+	test_when_finished "rm -fr pseudo-merge-sample-rate-zero" &&
+	git init pseudo-merge-sample-rate-zero &&
+	(
+		cd pseudo-merge-sample-rate-zero &&
+
+		test_commit_bulk 64 &&
+		tag_everything &&
+		git repack -ad &&
+
+		pack="$(ls .git/objects/pack/pack-*.pack)" &&
+
+		git config bitmapPseudoMerge.test.pattern "refs/tags/" &&
+		git config bitmapPseudoMerge.test.maxMerges 1 &&
+		git config bitmapPseudoMerge.test.sampleRate 0 &&
+		git config bitmapPseudoMerge.test.threshold now &&
+		git config bitmapPseudoMerge.test.stableThreshold never &&
+
+		git rev-parse HEAD~63 >in &&
+		test-tool bitmap write "$(basename $pack)" <in
+	)
+'
+
 test_done
-- 
2.47.3