t/t5326-multi-pack-bitmaps.sh - jrn/git - Git at Google

 #!/bin/sh

 test_description='exercise basic multi-pack bitmap functionality'
 . ./test-lib.sh
 . "${TEST_DIRECTORY}/lib-bitmap.sh"

 # We'll be writing our own midx and bitmaps, so avoid getting confused by the
 # automatic ones.
 GIT_TEST_MULTI_PACK_INDEX=0
 GIT_TEST_MULTI_PACK_INDEX_WRITE_BITMAP=0

 # This test exercise multi-pack bitmap functionality where the object order is
 # stored and read from a special chunk within the MIDX, so use the default
 # behavior here.
 sane_unset GIT_TEST_MIDX_WRITE_REV
 sane_unset GIT_TEST_MIDX_READ_RIDX

 bitmap_reuse_tests() {
 	from=$1
 	to=$2
 	writeLookupTable=false

 	for i in $3-${$#}
 	do
 		case $i in
 		"pack.writeBitmapLookupTable") writeLookupTable=true;;
 		esac
 	done

 	test_expect_success "setup pack reuse tests ($from -> $to)" '
 		rm -fr repo &&
 		git init repo &&
 		(
 			cd repo &&
 			git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
 			test_commit_bulk 16 &&
 			git tag old-tip &&

 			git config core.multiPackIndex true &&
 			if test "MIDX" = "$from"
 			then
 				git repack -Ad &&
 				git multi-pack-index write --bitmap
 			else
 				git repack -Adb
 			fi
 		)
 	'

 	test_expect_success "build bitmap from existing ($from -> $to)" '
 		(
 			cd repo &&
 			git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
 			test_commit_bulk --id=further 16 &&
 			git tag new-tip &&

 			if test "MIDX" = "$to"
 			then
 				git repack -d &&
 				git multi-pack-index write --bitmap
 			else
 				git repack -Adb
 			fi
 		)
 	'

 	test_expect_success "verify resulting bitmaps ($from -> $to)" '
 		(
 			cd repo &&
 			git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
 			git for-each-ref &&
 			git rev-list --test-bitmap refs/tags/old-tip &&
 			git rev-list --test-bitmap refs/tags/new-tip
 		)
 	'
 }

 test_midx_bitmap_cases () {
 	writeLookupTable=false
 	writeBitmapLookupTable=

 	for i in "$@"
 	do
 		case $i in
 		"pack.writeBitmapLookupTable")
 			writeLookupTable=true
 			writeBitmapLookupTable="$i"
 			;;
 		esac
 	done

 	test_expect_success 'setup test_repository' '
 		rm -rf * .git &&
 		git init &&
 		git config pack.writeBitmapLookupTable '"$writeLookupTable"'
 	'

 	midx_bitmap_core

 	bitmap_reuse_tests 'pack' 'MIDX' "$writeBitmapLookupTable"
 	bitmap_reuse_tests 'MIDX' 'pack' "$writeBitmapLookupTable"
 	bitmap_reuse_tests 'MIDX' 'MIDX' "$writeBitmapLookupTable"

 	test_expect_success 'missing object closure fails gracefully' '
 		rm -fr repo &&
 		git init repo &&
 		test_when_finished "rm -fr repo" &&
 		(
 			cd repo &&
 			git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&

 			test_commit loose &&
 			test_commit packed &&

 			# Do not pass "--revs"; we want a pack without the "loose"
 			# commit.
 			git pack-objects $objdir/pack/pack <<-EOF &&
 			$(git rev-parse packed)
 			EOF

 			test_must_fail git multi-pack-index write --bitmap 2>err &&
 			grep "doesn.t have full closure" err &&
 			test_path_is_missing $midx
 		)
 	'

 	midx_bitmap_partial_tests

 	test_expect_success 'removing a MIDX clears stale bitmaps' '
 		rm -fr repo &&
 		git init repo &&
 		test_when_finished "rm -fr repo" &&
 		(
 			cd repo &&
 			git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
 			test_commit base &&
 			git repack &&
 			git multi-pack-index write --bitmap &&

 			# Write a MIDX and bitmap; remove the MIDX but leave the bitmap.
 			stale_bitmap=$midx-$(midx_checksum $objdir).bitmap &&
 			rm $midx &&

 			# Then write a new MIDX.
 			test_commit new &&
 			git repack &&
 			git multi-pack-index write --bitmap &&

 			test_path_is_file $midx &&
 			test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&
 			test_path_is_missing $stale_bitmap
 		)
 	'

 	test_expect_success 'pack.preferBitmapTips' '
 		git init repo &&
 		test_when_finished "rm -fr repo" &&
 		(
 			cd repo &&
 			git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&

 			test_commit_bulk --message="%s" 103 &&

 			git log --format="%H" >commits.raw &&
 			sort <commits.raw >commits &&

 			git log --format="create refs/tags/%s %H" HEAD >refs &&
 			git update-ref --stdin <refs &&

 			git multi-pack-index write --bitmap &&
 			test_path_is_file $midx &&
 			test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&

 			test-tool bitmap list-commits | sort >bitmaps &&
 			comm -13 bitmaps commits >before &&
 			test_line_count = 1 before &&

 			perl -ne "printf(\"create refs/tags/include/%d \", $.); print" \
 				<before | git update-ref --stdin &&

 			rm -fr $midx-$(midx_checksum $objdir).bitmap &&
 			rm -fr $midx &&

 			git -c pack.preferBitmapTips=refs/tags/include \
 				multi-pack-index write --bitmap &&
 			test-tool bitmap list-commits | sort >bitmaps &&
 			comm -13 bitmaps commits >after &&

 			! test_cmp before after
 		)
 	'

 	test_expect_success 'writing a bitmap with --refs-snapshot' '
 		git init repo &&
 		test_when_finished "rm -fr repo" &&
 		(
 			cd repo &&
 			git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&

 			test_commit one &&
 			test_commit two &&

 			git rev-parse one >snapshot &&

 			git repack -ad &&

 			# First, write a MIDX which see both refs/tags/one and
 			# refs/tags/two (causing both of those commits to receive
 			# bitmaps).
 			git multi-pack-index write --bitmap &&

 			test_path_is_file $midx &&
 			test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&

 			test-tool bitmap list-commits | sort >bitmaps &&
 			grep "$(git rev-parse one)" bitmaps &&
 			grep "$(git rev-parse two)" bitmaps &&

 			rm -fr $midx-$(midx_checksum $objdir).bitmap &&
 			rm -fr $midx &&

 			# Then again, but with a refs snapshot which only sees
 			# refs/tags/one.
 			git multi-pack-index write --bitmap --refs-snapshot=snapshot &&

 			test_path_is_file $midx &&
 			test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&

 			test-tool bitmap list-commits | sort >bitmaps &&
 			grep "$(git rev-parse one)" bitmaps &&
 			! grep "$(git rev-parse two)" bitmaps
 		)
 	'

 	test_expect_success 'write a bitmap with --refs-snapshot (preferred tips)' '
 		git init repo &&
 		test_when_finished "rm -fr repo" &&
 		(
 			cd repo &&
 			git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&

 			test_commit_bulk --message="%s" 103 &&

 			git log --format="%H" >commits.raw &&
 			sort <commits.raw >commits &&

 			git log --format="create refs/tags/%s %H" HEAD >refs &&
 			git update-ref --stdin <refs &&

 			git multi-pack-index write --bitmap &&
 			test_path_is_file $midx &&
 			test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&

 			test-tool bitmap list-commits | sort >bitmaps &&
 			comm -13 bitmaps commits >before &&
 			test_line_count = 1 before &&

 			(
 				grep -vf before commits.raw &&
 				# mark missing commits as preferred
 				sed "s/^/+/" before
 			) >snapshot &&

 			rm -fr $midx-$(midx_checksum $objdir).bitmap &&
 			rm -fr $midx &&

 			git multi-pack-index write --bitmap --refs-snapshot=snapshot &&
 			test-tool bitmap list-commits | sort >bitmaps &&
 			comm -13 bitmaps commits >after &&

 			! test_cmp before after
 		)
 	'

 	test_expect_success 'hash-cache values are propagated from pack bitmaps' '
 		rm -fr repo &&
 		git init repo &&
 		test_when_finished "rm -fr repo" &&
 		(
 			cd repo &&
 			git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&

 			test_commit base &&
 			test_commit base2 &&
 			git repack -adb &&

 			test-tool bitmap dump-hashes >pack.raw &&
 			test_file_not_empty pack.raw &&
 			sort pack.raw >pack.hashes &&

 			test_commit new &&
 			git repack &&
 			git multi-pack-index write --bitmap &&

 			test-tool bitmap dump-hashes >midx.raw &&
 			sort midx.raw >midx.hashes &&

 			# ensure that every namehash in the pack bitmap can be found in
 			# the midx bitmap (i.e., that there are no oid-namehash pairs
 			# unique to the pack bitmap).
 			comm -23 pack.hashes midx.hashes >dropped.hashes &&
 			test_must_be_empty dropped.hashes
 		)
 	'

 	test_expect_success 'no .bitmap is written without any objects' '
 		rm -fr repo &&
 		git init repo &&
 		test_when_finished "rm -fr repo" &&
 		(
 			cd repo &&
 			git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&

 			empty="$(git pack-objects $objdir/pack/pack </dev/null)" &&
 			cat >packs <<-EOF &&
 			pack-$empty.idx
 			EOF

 			git multi-pack-index write --bitmap --stdin-packs \
 				<packs 2>err &&

 			grep "bitmap without any objects" err &&

 			test_path_is_file $midx &&
 			test_path_is_missing $midx-$(midx_checksum $objdir).bitmap
 		)
 	'

 	test_expect_success 'graceful fallback when missing reverse index' '
 		rm -fr repo &&
 		git init repo &&
 		test_when_finished "rm -fr repo" &&
 		(
 			cd repo &&
 			git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&

 			test_commit base &&

 			# write a pack and MIDX bitmap containing base
 			git repack -adb &&
 			git multi-pack-index write --bitmap &&

 			GIT_TEST_MIDX_READ_RIDX=0 \
 				git rev-list --use-bitmap-index HEAD 2>err &&
 			! grep "ignoring extra bitmap file" err
 		)
 	'
 }

 test_midx_bitmap_cases

 test_midx_bitmap_cases "pack.writeBitmapLookupTable"

 test_expect_success 'multi-pack-index write writes lookup table if enabled' '
 	rm -fr repo &&
 	git init repo &&
 	test_when_finished "rm -fr repo" &&
 	(
 		cd repo &&
 		test_commit base &&
 		git config pack.writeBitmapLookupTable true &&
 		git repack -ad &&
 		GIT_TRACE2_EVENT="$(pwd)/trace" \
 			git multi-pack-index write --bitmap &&
 		grep "\"label\":\"writing_lookup_table\"" trace
 	)
 '

 test_expect_success 'preferred pack change with existing MIDX bitmap' '
 	git init preferred-pack-with-existing &&
 	(
 		cd preferred-pack-with-existing &&

 		test_commit base &&
 		test_commit other &&

 		git rev-list --objects --no-object-names base >p1.objects &&
 		git rev-list --objects --no-object-names other >p2.objects &&

 		p1="$(git pack-objects "$objdir/pack/pack" \
 			--delta-base-offset <p1.objects)" &&
 		p2="$(git pack-objects "$objdir/pack/pack" \
 			--delta-base-offset <p2.objects)" &&

 		# Generate a MIDX containing the first two packs,
 		# marking p1 as preferred, and ensure that it can be
 		# successfully cloned.
 		git multi-pack-index write --bitmap \
 			--preferred-pack="pack-$p1.pack" &&
 		test_path_is_file $midx &&
 		test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&
 		git clone --no-local . clone1 &&

 		# Then generate a new pack which sorts ahead of any
 		# existing pack (by tweaking the pack prefix).
 		test_commit foo &&
 		git pack-objects --all --unpacked $objdir/pack/pack0 &&

 		# Generate a new MIDX which changes the preferred pack
 		# to a pack contained in the existing MIDX.
 		git multi-pack-index write --bitmap \
 			--preferred-pack="pack-$p2.pack" &&
 		test_path_is_file $midx &&
 		test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&

 		# When the above circumstances are met, the preferred
 		# pack should change appropriately and clones should
 		# (still) succeed.
 		git clone --no-local . clone2
 	)
 '

 test_done
	#!/bin/sh

	test_description='exercise basic multi-pack bitmap functionality'
	. ./test-lib.sh
	. "${TEST_DIRECTORY}/lib-bitmap.sh"

	# We'll be writing our own midx and bitmaps, so avoid getting confused by the
	# automatic ones.
	GIT_TEST_MULTI_PACK_INDEX=0
	GIT_TEST_MULTI_PACK_INDEX_WRITE_BITMAP=0

	# This test exercise multi-pack bitmap functionality where the object order is
	# stored and read from a special chunk within the MIDX, so use the default
	# behavior here.
	sane_unset GIT_TEST_MIDX_WRITE_REV
	sane_unset GIT_TEST_MIDX_READ_RIDX

	bitmap_reuse_tests() {
	from=$1
	to=$2
	writeLookupTable=false

	for i in $3-${$#}
	do
	case $i in
	"pack.writeBitmapLookupTable") writeLookupTable=true;;
	esac
	done

	test_expect_success "setup pack reuse tests ($from -> $to)" '
	rm -fr repo &&
	git init repo &&
	(
	cd repo &&
	git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
	test_commit_bulk 16 &&
	git tag old-tip &&

	git config core.multiPackIndex true &&
	if test "MIDX" = "$from"
	then
	git repack -Ad &&
	git multi-pack-index write --bitmap
	else
	git repack -Adb
	fi
	)
	'

	test_expect_success "build bitmap from existing ($from -> $to)" '
	(
	cd repo &&
	git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
	test_commit_bulk --id=further 16 &&
	git tag new-tip &&

	if test "MIDX" = "$to"
	then
	git repack -d &&
	git multi-pack-index write --bitmap
	else
	git repack -Adb
	fi
	)
	'

	test_expect_success "verify resulting bitmaps ($from -> $to)" '
	(
	cd repo &&
	git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
	git for-each-ref &&
	git rev-list --test-bitmap refs/tags/old-tip &&
	git rev-list --test-bitmap refs/tags/new-tip
	)
	'
	}

	test_midx_bitmap_cases () {
	writeLookupTable=false
	writeBitmapLookupTable=

	for i in "$@"
	do
	case $i in
	"pack.writeBitmapLookupTable")
	writeLookupTable=true
	writeBitmapLookupTable="$i"
	;;
	esac
	done

	test_expect_success 'setup test_repository' '
	rm -rf * .git &&
	git init &&
	git config pack.writeBitmapLookupTable '"$writeLookupTable"'
	'

	midx_bitmap_core

	bitmap_reuse_tests 'pack' 'MIDX' "$writeBitmapLookupTable"
	bitmap_reuse_tests 'MIDX' 'pack' "$writeBitmapLookupTable"
	bitmap_reuse_tests 'MIDX' 'MIDX' "$writeBitmapLookupTable"

	test_expect_success 'missing object closure fails gracefully' '
	rm -fr repo &&
	git init repo &&
	test_when_finished "rm -fr repo" &&
	(
	cd repo &&
	git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&

	test_commit loose &&
	test_commit packed &&

	# Do not pass "--revs"; we want a pack without the "loose"
	# commit.
	git pack-objects $objdir/pack/pack <<-EOF &&
	$(git rev-parse packed)
	EOF

	test_must_fail git multi-pack-index write --bitmap 2>err &&
	grep "doesn.t have full closure" err &&
	test_path_is_missing $midx
	)
	'

	midx_bitmap_partial_tests

	test_expect_success 'removing a MIDX clears stale bitmaps' '
	rm -fr repo &&
	git init repo &&
	test_when_finished "rm -fr repo" &&
	(
	cd repo &&
	git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
	test_commit base &&
	git repack &&
	git multi-pack-index write --bitmap &&

	# Write a MIDX and bitmap; remove the MIDX but leave the bitmap.
	stale_bitmap=$midx-$(midx_checksum $objdir).bitmap &&
	rm $midx &&

	# Then write a new MIDX.
	test_commit new &&
	git repack &&
	git multi-pack-index write --bitmap &&

	test_path_is_file $midx &&
	test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&
	test_path_is_missing $stale_bitmap
	)
	'

	test_expect_success 'pack.preferBitmapTips' '
	git init repo &&
	test_when_finished "rm -fr repo" &&
	(
	cd repo &&
	git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&

	test_commit_bulk --message="%s" 103 &&

	git log --format="%H" >commits.raw &&
	sort <commits.raw >commits &&

	git log --format="create refs/tags/%s %H" HEAD >refs &&
	git update-ref --stdin <refs &&

	git multi-pack-index write --bitmap &&
	test_path_is_file $midx &&
	test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&

	test-tool bitmap list-commits \| sort >bitmaps &&
	comm -13 bitmaps commits >before &&
	test_line_count = 1 before &&

	perl -ne "printf(\"create refs/tags/include/%d \", $.); print" \
	<before \| git update-ref --stdin &&

	rm -fr $midx-$(midx_checksum $objdir).bitmap &&
	rm -fr $midx &&

	git -c pack.preferBitmapTips=refs/tags/include \
	multi-pack-index write --bitmap &&
	test-tool bitmap list-commits \| sort >bitmaps &&
	comm -13 bitmaps commits >after &&

	! test_cmp before after
	)
	'

	test_expect_success 'writing a bitmap with --refs-snapshot' '
	git init repo &&
	test_when_finished "rm -fr repo" &&
	(
	cd repo &&
	git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&

	test_commit one &&
	test_commit two &&

	git rev-parse one >snapshot &&

	git repack -ad &&

	# First, write a MIDX which see both refs/tags/one and
	# refs/tags/two (causing both of those commits to receive
	# bitmaps).
	git multi-pack-index write --bitmap &&

	test_path_is_file $midx &&
	test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&

	test-tool bitmap list-commits \| sort >bitmaps &&
	grep "$(git rev-parse one)" bitmaps &&
	grep "$(git rev-parse two)" bitmaps &&

	rm -fr $midx-$(midx_checksum $objdir).bitmap &&
	rm -fr $midx &&

	# Then again, but with a refs snapshot which only sees
	# refs/tags/one.
	git multi-pack-index write --bitmap --refs-snapshot=snapshot &&

	test_path_is_file $midx &&
	test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&

	test-tool bitmap list-commits \| sort >bitmaps &&
	grep "$(git rev-parse one)" bitmaps &&
	! grep "$(git rev-parse two)" bitmaps
	)
	'

	test_expect_success 'write a bitmap with --refs-snapshot (preferred tips)' '
	git init repo &&
	test_when_finished "rm -fr repo" &&
	(
	cd repo &&
	git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&

	test_commit_bulk --message="%s" 103 &&

	git log --format="%H" >commits.raw &&
	sort <commits.raw >commits &&

	git log --format="create refs/tags/%s %H" HEAD >refs &&
	git update-ref --stdin <refs &&

	git multi-pack-index write --bitmap &&
	test_path_is_file $midx &&
	test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&

	test-tool bitmap list-commits \| sort >bitmaps &&
	comm -13 bitmaps commits >before &&
	test_line_count = 1 before &&

	(
	grep -vf before commits.raw &&
	# mark missing commits as preferred
	sed "s/^/+/" before
	) >snapshot &&

	rm -fr $midx-$(midx_checksum $objdir).bitmap &&
	rm -fr $midx &&

	git multi-pack-index write --bitmap --refs-snapshot=snapshot &&
	test-tool bitmap list-commits \| sort >bitmaps &&
	comm -13 bitmaps commits >after &&

	! test_cmp before after
	)
	'

	test_expect_success 'hash-cache values are propagated from pack bitmaps' '
	rm -fr repo &&
	git init repo &&
	test_when_finished "rm -fr repo" &&
	(
	cd repo &&
	git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&

	test_commit base &&
	test_commit base2 &&
	git repack -adb &&

	test-tool bitmap dump-hashes >pack.raw &&
	test_file_not_empty pack.raw &&
	sort pack.raw >pack.hashes &&

	test_commit new &&
	git repack &&
	git multi-pack-index write --bitmap &&

	test-tool bitmap dump-hashes >midx.raw &&
	sort midx.raw >midx.hashes &&

	# ensure that every namehash in the pack bitmap can be found in
	# the midx bitmap (i.e., that there are no oid-namehash pairs
	# unique to the pack bitmap).
	comm -23 pack.hashes midx.hashes >dropped.hashes &&
	test_must_be_empty dropped.hashes
	)
	'

	test_expect_success 'no .bitmap is written without any objects' '
	rm -fr repo &&
	git init repo &&
	test_when_finished "rm -fr repo" &&
	(
	cd repo &&
	git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&

	empty="$(git pack-objects $objdir/pack/pack </dev/null)" &&
	cat >packs <<-EOF &&
	pack-$empty.idx
	EOF

	git multi-pack-index write --bitmap --stdin-packs \
	<packs 2>err &&

	grep "bitmap without any objects" err &&

	test_path_is_file $midx &&
	test_path_is_missing $midx-$(midx_checksum $objdir).bitmap
	)
	'

	test_expect_success 'graceful fallback when missing reverse index' '
	rm -fr repo &&
	git init repo &&
	test_when_finished "rm -fr repo" &&
	(
	cd repo &&
	git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&

	test_commit base &&

	# write a pack and MIDX bitmap containing base
	git repack -adb &&
	git multi-pack-index write --bitmap &&

	GIT_TEST_MIDX_READ_RIDX=0 \
	git rev-list --use-bitmap-index HEAD 2>err &&
	! grep "ignoring extra bitmap file" err
	)
	'
	}

	test_midx_bitmap_cases

	test_midx_bitmap_cases "pack.writeBitmapLookupTable"

	test_expect_success 'multi-pack-index write writes lookup table if enabled' '
	rm -fr repo &&
	git init repo &&
	test_when_finished "rm -fr repo" &&
	(
	cd repo &&
	test_commit base &&
	git config pack.writeBitmapLookupTable true &&
	git repack -ad &&
	GIT_TRACE2_EVENT="$(pwd)/trace" \
	git multi-pack-index write --bitmap &&
	grep "\"label\":\"writing_lookup_table\"" trace
	)
	'

	test_expect_success 'preferred pack change with existing MIDX bitmap' '
	git init preferred-pack-with-existing &&
	(
	cd preferred-pack-with-existing &&

	test_commit base &&
	test_commit other &&

	git rev-list --objects --no-object-names base >p1.objects &&
	git rev-list --objects --no-object-names other >p2.objects &&

	p1="$(git pack-objects "$objdir/pack/pack" \
	--delta-base-offset <p1.objects)" &&
	p2="$(git pack-objects "$objdir/pack/pack" \
	--delta-base-offset <p2.objects)" &&

	# Generate a MIDX containing the first two packs,
	# marking p1 as preferred, and ensure that it can be
	# successfully cloned.
	git multi-pack-index write --bitmap \
	--preferred-pack="pack-$p1.pack" &&
	test_path_is_file $midx &&
	test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&
	git clone --no-local . clone1 &&

	# Then generate a new pack which sorts ahead of any
	# existing pack (by tweaking the pack prefix).
	test_commit foo &&
	git pack-objects --all --unpacked $objdir/pack/pack0 &&

	# Generate a new MIDX which changes the preferred pack
	# to a pack contained in the existing MIDX.
	git multi-pack-index write --bitmap \
	--preferred-pack="pack-$p2.pack" &&
	test_path_is_file $midx &&
	test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&

	# When the above circumstances are met, the preferred
	# pack should change appropriately and clones should
	# (still) succeed.
	git clone --no-local . clone2
	)
	'

	test_done