t/t5324-split-commit-graph.sh

   1 #!/bin/sh
   2
   3 test_description='split commit graph'
   4 . ./test-lib.sh
   5
   6 GIT_TEST_COMMIT_GRAPH=0
   7 GIT_TEST_COMMIT_GRAPH_CHANGED_PATHS=0
   8
   9 test_expect_success 'setup repo' '
  10         git init &&
  11         git config core.commitGraph true &&
  12         git config gc.writeCommitGraph false &&
  13         infodir=".git/objects/info" &&
  14         graphdir="$infodir/commit-graphs" &&
  15         test_oid_cache <<-EOM
  16         shallow sha1:2132
  17         shallow sha256:2436
  18
  19         base sha1:1408
  20         base sha256:1528
  21
  22         oid_version sha1:1
  23         oid_version sha256:2
  24         EOM
  25 '
  26
  27 graph_read_expect() {
  28         NUM_BASE=0
  29         if test ! -z $2
  30         then
  31                 NUM_BASE=$2
  32         fi
  33         OPTIONS=
  34         if test -z "$3"
  35         then
  36                 OPTIONS=" read_generation_data"
  37         fi
  38         cat >expect <<- EOF
  39         header: 43475048 1 $(test_oid oid_version) 4 $NUM_BASE
  40         num_commits: $1
  41         chunks: oid_fanout oid_lookup commit_metadata generation_data
  42         options:$OPTIONS
  43         EOF
  44         test-tool read-graph >output &&
  45         test_cmp expect output
  46 }
  47
  48 test_expect_success POSIXPERM 'tweak umask for modebit tests' '
  49         umask 022
  50 '
  51
  52 test_expect_success 'create commits and write commit-graph' '
  53         for i in $(test_seq 3)
  54         do
  55                 test_commit $i &&
  56                 git branch commits/$i || return 1
  57         done &&
  58         git commit-graph write --reachable &&
  59         test_path_is_file $infodir/commit-graph &&
  60         graph_read_expect 3
  61 '
  62
  63 graph_git_two_modes() {
  64         git ${2:+ -C "$2"} -c core.commitGraph=true $1 >output &&
  65         git ${2:+ -C "$2"} -c core.commitGraph=false $1 >expect &&
  66         test_cmp expect output
  67 }
  68
  69 graph_git_behavior() {
  70         MSG=$1
  71         BRANCH=$2
  72         COMPARE=$3
  73         DIR=$4
  74         test_expect_success "check normal git operations: $MSG" '
  75                 graph_git_two_modes "log --oneline $BRANCH" "$DIR" &&
  76                 graph_git_two_modes "log --topo-order $BRANCH" "$DIR" &&
  77                 graph_git_two_modes "log --graph $COMPARE..$BRANCH" "$DIR" &&
  78                 graph_git_two_modes "branch -vv" "$DIR" &&
  79                 graph_git_two_modes "merge-base -a $BRANCH $COMPARE" "$DIR"
  80         '
  81 }
  82
  83 graph_git_behavior 'graph exists' commits/3 commits/1
  84
  85 verify_chain_files_exist() {
  86         for hash in $(cat $1/commit-graph-chain)
  87         do
  88                 test_path_is_file $1/graph-$hash.graph || return 1
  89         done
  90 }
  91
  92 test_expect_success 'add more commits, and write a new base graph' '
  93         git reset --hard commits/1 &&
  94         for i in $(test_seq 4 5)
  95         do
  96                 test_commit $i &&
  97                 git branch commits/$i || return 1
  98         done &&
  99         git reset --hard commits/2 &&
 100         for i in $(test_seq 6 10)
 101         do
 102                 test_commit $i &&
 103                 git branch commits/$i || return 1
 104         done &&
 105         git reset --hard commits/2 &&
 106         git merge commits/4 &&
 107         git branch merge/1 &&
 108         git reset --hard commits/4 &&
 109         git merge commits/6 &&
 110         git branch merge/2 &&
 111         git commit-graph write --reachable &&
 112         graph_read_expect 12
 113 '
 114
 115 test_expect_success 'fork and fail to base a chain on a commit-graph file' '
 116         test_when_finished rm -rf fork &&
 117         git clone . fork &&
 118         (
 119                 cd fork &&
 120                 rm .git/objects/info/commit-graph &&
 121                 echo "$(pwd)/../.git/objects" >.git/objects/info/alternates &&
 122                 test_commit new-commit &&
 123                 git commit-graph write --reachable --split &&
 124                 test_path_is_file $graphdir/commit-graph-chain &&
 125                 test_line_count = 1 $graphdir/commit-graph-chain &&
 126                 verify_chain_files_exist $graphdir
 127         )
 128 '
 129
 130 test_expect_success 'add three more commits, write a tip graph' '
 131         git reset --hard commits/3 &&
 132         git merge merge/1 &&
 133         git merge commits/5 &&
 134         git merge merge/2 &&
 135         git branch merge/3 &&
 136         git commit-graph write --reachable --split &&
 137         test_path_is_missing $infodir/commit-graph &&
 138         test_path_is_file $graphdir/commit-graph-chain &&
 139         ls $graphdir/graph-*.graph >graph-files &&
 140         test_line_count = 2 graph-files &&
 141         verify_chain_files_exist $graphdir
 142 '
 143
 144 graph_git_behavior 'split commit-graph: merge 3 vs 2' merge/3 merge/2
 145
 146 test_expect_success 'add one commit, write a tip graph' '
 147         test_commit 11 &&
 148         git branch commits/11 &&
 149         git commit-graph write --reachable --split &&
 150         test_path_is_missing $infodir/commit-graph &&
 151         test_path_is_file $graphdir/commit-graph-chain &&
 152         ls $graphdir/graph-*.graph >graph-files &&
 153         test_line_count = 3 graph-files &&
 154         verify_chain_files_exist $graphdir
 155 '
 156
 157 graph_git_behavior 'three-layer commit-graph: commit 11 vs 6' commits/11 commits/6
 158
 159 test_expect_success 'add one commit, write a merged graph' '
 160         test_commit 12 &&
 161         git branch commits/12 &&
 162         git commit-graph write --reachable --split &&
 163         test_path_is_file $graphdir/commit-graph-chain &&
 164         test_line_count = 2 $graphdir/commit-graph-chain &&
 165         ls $graphdir/graph-*.graph >graph-files &&
 166         test_line_count = 2 graph-files &&
 167         verify_chain_files_exist $graphdir
 168 '
 169
 170 graph_git_behavior 'merged commit-graph: commit 12 vs 6' commits/12 commits/6
 171
 172 test_expect_success 'create fork and chain across alternate' '
 173         git clone . fork &&
 174         (
 175                 cd fork &&
 176                 git config core.commitGraph true &&
 177                 rm -rf $graphdir &&
 178                 echo "$(pwd)/../.git/objects" >.git/objects/info/alternates &&
 179                 test_commit 13 &&
 180                 git branch commits/13 &&
 181                 git commit-graph write --reachable --split &&
 182                 test_path_is_file $graphdir/commit-graph-chain &&
 183                 test_line_count = 3 $graphdir/commit-graph-chain &&
 184                 ls $graphdir/graph-*.graph >graph-files &&
 185                 test_line_count = 1 graph-files &&
 186                 git -c core.commitGraph=true  rev-list HEAD >expect &&
 187                 git -c core.commitGraph=false rev-list HEAD >actual &&
 188                 test_cmp expect actual &&
 189                 test_commit 14 &&
 190                 git commit-graph write --reachable --split --object-dir=.git/objects/ &&
 191                 test_line_count = 3 $graphdir/commit-graph-chain &&
 192                 ls $graphdir/graph-*.graph >graph-files &&
 193                 test_line_count = 1 graph-files
 194         )
 195 '
 196
 197 if test -d fork
 198 then
 199         graph_git_behavior 'alternate: commit 13 vs 6' commits/13 origin/commits/6 "fork"
 200 fi
 201
 202 test_expect_success 'test merge stragety constants' '
 203         git clone . merge-2 &&
 204         (
 205                 cd merge-2 &&
 206                 git config core.commitGraph true &&
 207                 test_line_count = 2 $graphdir/commit-graph-chain &&
 208                 test_commit 14 &&
 209                 git commit-graph write --reachable --split --size-multiple=2 &&
 210                 test_line_count = 3 $graphdir/commit-graph-chain
 211
 212         ) &&
 213         git clone . merge-10 &&
 214         (
 215                 cd merge-10 &&
 216                 git config core.commitGraph true &&
 217                 test_line_count = 2 $graphdir/commit-graph-chain &&
 218                 test_commit 14 &&
 219                 git commit-graph write --reachable --split --size-multiple=10 &&
 220                 test_line_count = 1 $graphdir/commit-graph-chain &&
 221                 ls $graphdir/graph-*.graph >graph-files &&
 222                 test_line_count = 1 graph-files
 223         ) &&
 224         git clone . merge-10-expire &&
 225         (
 226                 cd merge-10-expire &&
 227                 git config core.commitGraph true &&
 228                 test_line_count = 2 $graphdir/commit-graph-chain &&
 229                 test_commit 15 &&
 230                 touch $graphdir/to-delete.graph $graphdir/to-keep.graph &&
 231                 test-tool chmtime =1546362000 $graphdir/to-delete.graph &&
 232                 test-tool chmtime =1546362001 $graphdir/to-keep.graph &&
 233                 git commit-graph write --reachable --split --size-multiple=10 \
 234                         --expire-time="2019-01-01 12:00 -05:00" &&
 235                 test_line_count = 1 $graphdir/commit-graph-chain &&
 236                 test_path_is_missing $graphdir/to-delete.graph &&
 237                 test_path_is_file $graphdir/to-keep.graph &&
 238                 ls $graphdir/graph-*.graph >graph-files &&
 239                 test_line_count = 3 graph-files
 240         ) &&
 241         git clone --no-hardlinks . max-commits &&
 242         (
 243                 cd max-commits &&
 244                 git config core.commitGraph true &&
 245                 test_line_count = 2 $graphdir/commit-graph-chain &&
 246                 test_commit 16 &&
 247                 test_commit 17 &&
 248                 git commit-graph write --reachable --split --max-commits=1 &&
 249                 test_line_count = 1 $graphdir/commit-graph-chain &&
 250                 ls $graphdir/graph-*.graph >graph-files &&
 251                 test_line_count = 1 graph-files
 252         )
 253 '
 254
 255 test_expect_success 'remove commit-graph-chain file after flattening' '
 256         git clone . flatten &&
 257         (
 258                 cd flatten &&
 259                 test_line_count = 2 $graphdir/commit-graph-chain &&
 260                 git commit-graph write --reachable &&
 261                 test_path_is_missing $graphdir/commit-graph-chain &&
 262                 ls $graphdir >graph-files &&
 263                 test_line_count = 0 graph-files
 264         )
 265 '
 266
 267 corrupt_file() {
 268         file=$1
 269         pos=$2
 270         data="${3:-\0}"
 271         chmod a+w "$file" &&
 272         printf "$data" | dd of="$file" bs=1 seek="$pos" conv=notrunc
 273 }
 274
 275 test_expect_success 'verify hashes along chain, even in shallow' '
 276         git clone --no-hardlinks . verify &&
 277         (
 278                 cd verify &&
 279                 git commit-graph verify &&
 280                 base_file=$graphdir/graph-$(head -n 1 $graphdir/commit-graph-chain).graph &&
 281                 corrupt_file "$base_file" $(test_oid shallow) "\01" &&
 282                 test_must_fail git commit-graph verify --shallow 2>test_err &&
 283                 grep -v "^+" test_err >err &&
 284                 test_i18ngrep "incorrect checksum" err
 285         )
 286 '
 287
 288 test_expect_success 'verify notices chain slice which is bogus (base)' '
 289         git clone --no-hardlinks . verify-chain-bogus-base &&
 290         (
 291                 cd verify-chain-bogus-base &&
 292                 git commit-graph verify &&
 293                 base_file=$graphdir/graph-$(sed -n 1p $graphdir/commit-graph-chain).graph &&
 294                 echo "garbage" >$base_file &&
 295                 test_must_fail git commit-graph verify 2>test_err &&
 296                 grep -v "^+" test_err >err &&
 297                 grep "commit-graph file is too small" err
 298         )
 299 '
 300
 301 test_expect_success 'verify notices chain slice which is bogus (tip)' '
 302         git clone --no-hardlinks . verify-chain-bogus-tip &&
 303         (
 304                 cd verify-chain-bogus-tip &&
 305                 git commit-graph verify &&
 306                 tip_file=$graphdir/graph-$(sed -n 2p $graphdir/commit-graph-chain).graph &&
 307                 echo "garbage" >$tip_file &&
 308                 test_must_fail git commit-graph verify 2>test_err &&
 309                 grep -v "^+" test_err >err &&
 310                 grep "commit-graph file is too small" err
 311         )
 312 '
 313
 314 test_expect_success 'verify --shallow does not check base contents' '
 315         git clone --no-hardlinks . verify-shallow &&
 316         (
 317                 cd verify-shallow &&
 318                 git commit-graph verify &&
 319                 base_file=$graphdir/graph-$(head -n 1 $graphdir/commit-graph-chain).graph &&
 320                 corrupt_file "$base_file" 1500 "\01" &&
 321                 git commit-graph verify --shallow &&
 322                 test_must_fail git commit-graph verify 2>test_err &&
 323                 grep -v "^+" test_err >err &&
 324                 test_i18ngrep "incorrect checksum" err
 325         )
 326 '
 327
 328 test_expect_success 'warn on base graph chunk incorrect' '
 329         git clone --no-hardlinks . base-chunk &&
 330         (
 331                 cd base-chunk &&
 332                 git commit-graph verify &&
 333                 base_file=$graphdir/graph-$(tail -n 1 $graphdir/commit-graph-chain).graph &&
 334                 corrupt_file "$base_file" $(test_oid base) "\01" &&
 335                 test_must_fail git commit-graph verify --shallow 2>test_err &&
 336                 grep -v "^+" test_err >err &&
 337                 test_i18ngrep "commit-graph chain does not match" err
 338         )
 339 '
 340
 341 test_expect_success 'verify after commit-graph-chain corruption (base)' '
 342         git clone --no-hardlinks . verify-chain-base &&
 343         (
 344                 cd verify-chain-base &&
 345                 corrupt_file "$graphdir/commit-graph-chain" 30 "G" &&
 346                 test_must_fail git commit-graph verify 2>test_err &&
 347                 grep -v "^+" test_err >err &&
 348                 test_i18ngrep "invalid commit-graph chain" err &&
 349                 corrupt_file "$graphdir/commit-graph-chain" 30 "A" &&
 350                 test_must_fail git commit-graph verify 2>test_err &&
 351                 grep -v "^+" test_err >err &&
 352                 test_i18ngrep "unable to find all commit-graph files" err
 353         )
 354 '
 355
 356 test_expect_success 'verify after commit-graph-chain corruption (tip)' '
 357         git clone --no-hardlinks . verify-chain-tip &&
 358         (
 359                 cd verify-chain-tip &&
 360                 corrupt_file "$graphdir/commit-graph-chain" 70 "G" &&
 361                 test_must_fail git commit-graph verify 2>test_err &&
 362                 grep -v "^+" test_err >err &&
 363                 test_i18ngrep "invalid commit-graph chain" err &&
 364                 corrupt_file "$graphdir/commit-graph-chain" 70 "A" &&
 365                 test_must_fail git commit-graph verify 2>test_err &&
 366                 grep -v "^+" test_err >err &&
 367                 test_i18ngrep "unable to find all commit-graph files" err
 368         )
 369 '
 370
 371 test_expect_success 'verify notices too-short chain file' '
 372         git clone --no-hardlinks . verify-chain-short &&
 373         (
 374                 cd verify-chain-short &&
 375                 git commit-graph verify &&
 376                 echo "garbage" >$graphdir/commit-graph-chain &&
 377                 test_must_fail git commit-graph verify 2>test_err &&
 378                 grep -v "^+" test_err >err &&
 379                 grep "commit-graph chain file too small" err
 380         )
 381 '
 382
 383 test_expect_success 'verify across alternates' '
 384         git clone --no-hardlinks . verify-alt &&
 385         (
 386                 cd verify-alt &&
 387                 rm -rf $graphdir &&
 388                 altdir="$(pwd)/../.git/objects" &&
 389                 echo "$altdir" >.git/objects/info/alternates &&
 390                 git commit-graph verify --object-dir="$altdir/" &&
 391                 test_commit extra &&
 392                 git commit-graph write --reachable --split &&
 393                 tip_file=$graphdir/graph-$(tail -n 1 $graphdir/commit-graph-chain).graph &&
 394                 corrupt_file "$tip_file" 1500 "\01" &&
 395                 test_must_fail git commit-graph verify --shallow 2>test_err &&
 396                 grep -v "^+" test_err >err &&
 397                 test_i18ngrep "incorrect checksum" err
 398         )
 399 '
 400
 401 test_expect_success 'add octopus merge' '
 402         git reset --hard commits/10 &&
 403         git merge commits/3 commits/4 &&
 404         git branch merge/octopus &&
 405         git commit-graph write --reachable --split &&
 406         git commit-graph verify --progress 2>err &&
 407         test_line_count = 1 err &&
 408         grep "Verifying commits in commit graph: 100% (18/18)" err &&
 409         test_i18ngrep ! warning err &&
 410         test_line_count = 3 $graphdir/commit-graph-chain
 411 '
 412
 413 graph_git_behavior 'graph exists' merge/octopus commits/12
 414
 415 test_expect_success 'split across alternate where alternate is not split' '
 416         git commit-graph write --reachable &&
 417         test_path_is_file .git/objects/info/commit-graph &&
 418         cp .git/objects/info/commit-graph . &&
 419         git clone --no-hardlinks . alt-split &&
 420         (
 421                 cd alt-split &&
 422                 rm -f .git/objects/info/commit-graph &&
 423                 echo "$(pwd)"/../.git/objects >.git/objects/info/alternates &&
 424                 test_commit 18 &&
 425                 git commit-graph write --reachable --split &&
 426                 test_line_count = 1 $graphdir/commit-graph-chain
 427         ) &&
 428         test_cmp commit-graph .git/objects/info/commit-graph
 429 '
 430
 431 test_expect_success '--split=no-merge always writes an incremental' '
 432         test_when_finished rm -rf a b &&
 433         rm -rf $graphdir $infodir/commit-graph &&
 434         git reset --hard commits/2 &&
 435         git rev-list HEAD~1 >a &&
 436         git rev-list HEAD >b &&
 437         git commit-graph write --split --stdin-commits <a &&
 438         git commit-graph write --split=no-merge --stdin-commits <b &&
 439         test_line_count = 2 $graphdir/commit-graph-chain
 440 '
 441
 442 test_expect_success '--split=replace replaces the chain' '
 443         rm -rf $graphdir $infodir/commit-graph &&
 444         git reset --hard commits/3 &&
 445         git rev-list -1 HEAD~2 >a &&
 446         git rev-list -1 HEAD~1 >b &&
 447         git rev-list -1 HEAD >c &&
 448         git commit-graph write --split=no-merge --stdin-commits <a &&
 449         git commit-graph write --split=no-merge --stdin-commits <b &&
 450         git commit-graph write --split=no-merge --stdin-commits <c &&
 451         test_line_count = 3 $graphdir/commit-graph-chain &&
 452         git commit-graph write --stdin-commits --split=replace <b &&
 453         test_path_is_missing $infodir/commit-graph &&
 454         test_path_is_file $graphdir/commit-graph-chain &&
 455         ls $graphdir/graph-*.graph >graph-files &&
 456         test_line_count = 1 graph-files &&
 457         verify_chain_files_exist $graphdir &&
 458         graph_read_expect 2
 459 '
 460
 461 test_expect_success ULIMIT_FILE_DESCRIPTORS 'handles file descriptor exhaustion' '
 462         git init ulimit &&
 463         (
 464                 cd ulimit &&
 465                 for i in $(test_seq 64)
 466                 do
 467                         test_commit $i &&
 468                         run_with_limited_open_files test_might_fail git commit-graph write \
 469                                 --split=no-merge --reachable || return 1
 470                 done
 471         )
 472 '
 473
 474 while read mode modebits
 475 do
 476         test_expect_success POSIXPERM "split commit-graph respects core.sharedrepository $mode" '
 477                 rm -rf $graphdir $infodir/commit-graph &&
 478                 git reset --hard commits/1 &&
 479                 test_config core.sharedrepository "$mode" &&
 480                 git commit-graph write --split --reachable &&
 481                 ls $graphdir/graph-*.graph >graph-files &&
 482                 test_line_count = 1 graph-files &&
 483                 echo "$modebits" >expect &&
 484                 test_modebits $graphdir/graph-*.graph >actual &&
 485                 test_cmp expect actual &&
 486                 test_modebits $graphdir/commit-graph-chain >actual &&
 487                 test_cmp expect actual
 488         '
 489 done <<\EOF
 490 0666 -r--r--r--
 491 0600 -r--------
 492 EOF
 493
 494 test_expect_success '--split=replace with partial Bloom data' '
 495         rm -rf $graphdir $infodir/commit-graph &&
 496         git reset --hard commits/3 &&
 497         git rev-list -1 HEAD~2 >a &&
 498         git rev-list -1 HEAD~1 >b &&
 499         git commit-graph write --split=no-merge --stdin-commits --changed-paths <a &&
 500         git commit-graph write --split=no-merge --stdin-commits <b &&
 501         git commit-graph write --split=replace --stdin-commits --changed-paths <c &&
 502         ls $graphdir/graph-*.graph >graph-files &&
 503         test_line_count = 1 graph-files &&
 504         verify_chain_files_exist $graphdir
 505 '
 506
 507 test_expect_success 'prevent regression for duplicate commits across layers' '
 508         git init dup &&
 509         git -C dup commit --allow-empty -m one &&
 510         git -C dup -c core.commitGraph=false commit-graph write --split=no-merge --reachable 2>err &&
 511         test_i18ngrep "attempting to write a commit-graph" err &&
 512         git -C dup commit-graph write --split=no-merge --reachable &&
 513         git -C dup commit --allow-empty -m two &&
 514         git -C dup commit-graph write --split=no-merge --reachable &&
 515         git -C dup commit --allow-empty -m three &&
 516         git -C dup commit-graph write --split --reachable &&
 517         git -C dup commit-graph verify
 518 '
 519
 520 NUM_FIRST_LAYER_COMMITS=64
 521 NUM_SECOND_LAYER_COMMITS=16
 522 NUM_THIRD_LAYER_COMMITS=7
 523 NUM_FOURTH_LAYER_COMMITS=8
 524 NUM_FIFTH_LAYER_COMMITS=16
 525 SECOND_LAYER_SEQUENCE_START=$(($NUM_FIRST_LAYER_COMMITS + 1))
 526 SECOND_LAYER_SEQUENCE_END=$(($SECOND_LAYER_SEQUENCE_START + $NUM_SECOND_LAYER_COMMITS - 1))
 527 THIRD_LAYER_SEQUENCE_START=$(($SECOND_LAYER_SEQUENCE_END + 1))
 528 THIRD_LAYER_SEQUENCE_END=$(($THIRD_LAYER_SEQUENCE_START + $NUM_THIRD_LAYER_COMMITS - 1))
 529 FOURTH_LAYER_SEQUENCE_START=$(($THIRD_LAYER_SEQUENCE_END + 1))
 530 FOURTH_LAYER_SEQUENCE_END=$(($FOURTH_LAYER_SEQUENCE_START + $NUM_FOURTH_LAYER_COMMITS - 1))
 531 FIFTH_LAYER_SEQUENCE_START=$(($FOURTH_LAYER_SEQUENCE_END + 1))
 532 FIFTH_LAYER_SEQUENCE_END=$(($FIFTH_LAYER_SEQUENCE_START + $NUM_FIFTH_LAYER_COMMITS - 1))
 533
 534 # Current split graph chain:
 535 #
 536 #     16 commits (No GDAT)
 537 # ------------------------
 538 #     64 commits (GDAT)
 539 #
 540 test_expect_success 'setup repo for mixed generation commit-graph-chain' '
 541         graphdir=".git/objects/info/commit-graphs" &&
 542         test_oid_cache <<-EOF &&
 543         oid_version sha1:1
 544         oid_version sha256:2
 545         EOF
 546         git init mixed &&
 547         (
 548                 cd mixed &&
 549                 git config core.commitGraph true &&
 550                 git config gc.writeCommitGraph false &&
 551                 for i in $(test_seq $NUM_FIRST_LAYER_COMMITS)
 552                 do
 553                         test_commit $i &&
 554                         git branch commits/$i || return 1
 555                 done &&
 556                 git -c commitGraph.generationVersion=2 commit-graph write --reachable --split &&
 557                 graph_read_expect $NUM_FIRST_LAYER_COMMITS &&
 558                 test_line_count = 1 $graphdir/commit-graph-chain &&
 559                 for i in $(test_seq $SECOND_LAYER_SEQUENCE_START $SECOND_LAYER_SEQUENCE_END)
 560                 do
 561                         test_commit $i &&
 562                         git branch commits/$i || return 1
 563                 done &&
 564                 git -c commitGraph.generationVersion=1 commit-graph write --reachable --split=no-merge &&
 565                 test_line_count = 2 $graphdir/commit-graph-chain &&
 566                 test-tool read-graph >output &&
 567                 cat >expect <<-EOF &&
 568                 header: 43475048 1 $(test_oid oid_version) 4 1
 569                 num_commits: $NUM_SECOND_LAYER_COMMITS
 570                 chunks: oid_fanout oid_lookup commit_metadata
 571                 options:
 572                 EOF
 573                 test_cmp expect output &&
 574                 git commit-graph verify &&
 575                 cat $graphdir/commit-graph-chain
 576         )
 577 '
 578
 579 # The new layer will be added without generation data chunk as it was not
 580 # present on the layer underneath it.
 581 #
 582 #      7 commits (No GDAT)
 583 # ------------------------
 584 #     16 commits (No GDAT)
 585 # ------------------------
 586 #     64 commits (GDAT)
 587 #
 588 test_expect_success 'do not write generation data chunk if not present on existing tip' '
 589         git clone mixed mixed-no-gdat &&
 590         (
 591                 cd mixed-no-gdat &&
 592                 for i in $(test_seq $THIRD_LAYER_SEQUENCE_START $THIRD_LAYER_SEQUENCE_END)
 593                 do
 594                         test_commit $i &&
 595                         git branch commits/$i || return 1
 596                 done &&
 597                 git commit-graph write --reachable --split=no-merge &&
 598                 test_line_count = 3 $graphdir/commit-graph-chain &&
 599                 test-tool read-graph >output &&
 600                 cat >expect <<-EOF &&
 601                 header: 43475048 1 $(test_oid oid_version) 4 2
 602                 num_commits: $NUM_THIRD_LAYER_COMMITS
 603                 chunks: oid_fanout oid_lookup commit_metadata
 604                 options:
 605                 EOF
 606                 test_cmp expect output &&
 607                 git commit-graph verify
 608         )
 609 '
 610
 611 # Number of commits in each layer of the split-commit graph before merge:
 612 #
 613 #      8 commits (No GDAT)
 614 # ------------------------
 615 #      7 commits (No GDAT)
 616 # ------------------------
 617 #     16 commits (No GDAT)
 618 # ------------------------
 619 #     64 commits (GDAT)
 620 #
 621 # The top two layers are merged and do not have generation data chunk as layer below them does
 622 # not have generation data chunk.
 623 #
 624 #     15 commits (No GDAT)
 625 # ------------------------
 626 #     16 commits (No GDAT)
 627 # ------------------------
 628 #     64 commits (GDAT)
 629 #
 630 test_expect_success 'do not write generation data chunk if the topmost remaining layer does not have generation data chunk' '
 631         git clone mixed-no-gdat mixed-merge-no-gdat &&
 632         (
 633                 cd mixed-merge-no-gdat &&
 634                 for i in $(test_seq $FOURTH_LAYER_SEQUENCE_START $FOURTH_LAYER_SEQUENCE_END)
 635                 do
 636                         test_commit $i &&
 637                         git branch commits/$i || return 1
 638                 done &&
 639                 git commit-graph write --reachable --split --size-multiple 1 &&
 640                 test_line_count = 3 $graphdir/commit-graph-chain &&
 641                 test-tool read-graph >output &&
 642                 cat >expect <<-EOF &&
 643                 header: 43475048 1 $(test_oid oid_version) 4 2
 644                 num_commits: $(($NUM_THIRD_LAYER_COMMITS + $NUM_FOURTH_LAYER_COMMITS))
 645                 chunks: oid_fanout oid_lookup commit_metadata
 646                 options:
 647                 EOF
 648                 test_cmp expect output &&
 649                 git commit-graph verify
 650         )
 651 '
 652
 653 # Number of commits in each layer of the split-commit graph before merge:
 654 #
 655 #     16 commits (No GDAT)
 656 # ------------------------
 657 #     15 commits (No GDAT)
 658 # ------------------------
 659 #     16 commits (No GDAT)
 660 # ------------------------
 661 #     64 commits (GDAT)
 662 #
 663 # The top three layers are merged and has generation data chunk as the topmost remaining layer
 664 # has generation data chunk.
 665 #
 666 #     47 commits (GDAT)
 667 # ------------------------
 668 #     64 commits (GDAT)
 669 #
 670 test_expect_success 'write generation data chunk if topmost remaining layer has generation data chunk' '
 671         git clone mixed-merge-no-gdat mixed-merge-gdat &&
 672         (
 673                 cd mixed-merge-gdat &&
 674                 for i in $(test_seq $FIFTH_LAYER_SEQUENCE_START $FIFTH_LAYER_SEQUENCE_END)
 675                 do
 676                         test_commit $i &&
 677                         git branch commits/$i || return 1
 678                 done &&
 679                 git commit-graph write --reachable --split --size-multiple 1 &&
 680                 test_line_count = 2 $graphdir/commit-graph-chain &&
 681                 test-tool read-graph >output &&
 682                 cat >expect <<-EOF &&
 683                 header: 43475048 1 $(test_oid oid_version) 5 1
 684                 num_commits: $(($NUM_SECOND_LAYER_COMMITS + $NUM_THIRD_LAYER_COMMITS + $NUM_FOURTH_LAYER_COMMITS + $NUM_FIFTH_LAYER_COMMITS))
 685                 chunks: oid_fanout oid_lookup commit_metadata generation_data
 686                 options: read_generation_data
 687                 EOF
 688                 test_cmp expect output
 689         )
 690 '
 691
 692 test_expect_success 'write generation data chunk when commit-graph chain is replaced' '
 693         git clone mixed mixed-replace &&
 694         (
 695                 cd mixed-replace &&
 696                 git commit-graph write --reachable --split=replace &&
 697                 test_path_is_file $graphdir/commit-graph-chain &&
 698                 test_line_count = 1 $graphdir/commit-graph-chain &&
 699                 verify_chain_files_exist $graphdir &&
 700                 graph_read_expect $(($NUM_FIRST_LAYER_COMMITS + $NUM_SECOND_LAYER_COMMITS)) &&
 701                 git commit-graph verify
 702         )
 703 '
 704
 705 test_done