add remaining baseline tests along with permutations

Author: Byron

gix-revision/src/merge_base.rs

@@ -14,7 +14,7 @@ bitflags::bitflags! {
     }
 }
 
-/// The error returned by the [`merge_base()`][function::describe()] function.
+/// The error returned by the [`merge_base()`][function::merge_base()] function.
 #[derive(Debug, thiserror::Error)]
 #[allow(missing_docs)]
 pub enum Error {

gix-revision/tests/fixtures/generated-archives/make_merge_base_repos.tar

@@ -4,7 +4,7 @@ set -eu -o pipefail
 git init
 
 EMPTY_TREE=$(git mktree </dev/null)
-function mkcommit () {
+function ofs_commit () {
   local OFFSET_SECONDS=$1
   local COMMIT_NAME=$2
   shift 2
@@ -33,8 +33,8 @@ function baseline() {
 
 # Merge-bases adapted from Git test suite
 # No merge base
-mkcommit 0 DA
-mkcommit 100 DB
+ofs_commit 0 DA
+ofs_commit 100 DB
 {
   echo "just-one-returns-one-in-code"
   echo $(git rev-parse DA)
@@ -52,19 +52,20 @@ mkcommit 100 DB
 #  \  `---------G   \
 #   \                \
 #    F----------------H
-E=$(mkcommit 5 E)
-D=$(mkcommit 4 D $E)
-F=$(mkcommit 6 F $E)
-C=$(mkcommit 3 C $D)
-B=$(mkcommit 2 B $C)
-A=$(mkcommit 1 A $B)
-G=$(mkcommit 7 G $B $E)
-H=$(mkcommit 8 H $A $F)
+E=$(ofs_commit 5 E)
+D=$(ofs_commit 4 D $E)
+F=$(ofs_commit 6 F $E)
+C=$(ofs_commit 3 C $D)
+B=$(ofs_commit 2 B $C)
+A=$(ofs_commit 1 A $B)
+G=$(ofs_commit 7 G $B $E)
+H=$(ofs_commit 8 H $A $F)
 
 {
   baseline G H
 } > 2_a.baseline
 
+# Permutation testing - let's do it early to avoid too many permutations
 commits=$(git log --all --format=%s)
 commit_array=($commits)
 num_commits=${#commit_array[@]}
@@ -75,5 +76,147 @@ for ((i=0; i<num_commits; i++)); do
     done
 done > 3_permutations.baseline
 
+# Timestamps cannot be trusted.
+#
+#               Relative
+# Structure     timestamps
+#
+#   PL  PR        +4  +4
+#  /  \/  \      /  \/  \
+# L2  C2  R2    +3  -1  +3
+# |   |   |     |   |   |
+# L1  C1  R1    +2  -2  +2
+# |   |   |     |   |   |
+# L0  C0  R0    +1  -3  +1
+#   \ |  /        \ |  /
+#     S             0
+#
+# The left and right chains of commits can be of any length and complexity as
+# long as all of the timestamps are greater than that of S.
+S=$(ofs_commit  0 S)
+
+C0=$(ofs_commit -3 C0 $S)
+C1=$(ofs_commit -2 C1 $C0)
+C2=$(ofs_commit -1 C2 $C1)
+
+L0=$(ofs_commit 1 L0 $S)
+L1=$(ofs_commit 2 L1 $L0)
+L2=$(ofs_commit 3 L2 $L1)
+
+R0=$(ofs_commit 1 R0 $S)
+R1=$(ofs_commit 2 R1 $R0)
+R2=$(ofs_commit 3 R2 $R1)
+
+PL=$(ofs_commit 4 PL $L2 $C2)
+PR=$(ofs_commit 4 PR $C2 $R2)
+
+{
+  baseline PL PR
+} > 4_b.baseline
+
+
+function tick () {
+  if test -z "${tick+set}"
+  then
+    tick=1112911993
+  else
+    tick=$(($tick + 60))
+  fi
+  GIT_COMMITTER_DATE="$tick -0700"
+  GIT_AUTHOR_DATE="$tick -0700"
+  export GIT_COMMITTER_DATE GIT_AUTHOR_DATE
+}
+
+tick
+function commit() {
+  local message=${1:?first argument is the commit message}
+  local date=${2:-}
+  if [ -n "$date" ]; then
+    export GIT_COMMITTER_DATE="$date"
+  else
+    tick
+  fi
+  git commit --allow-empty -m "$message"
+  git tag "$message"
+}
+
+# * C (MMC) * B (MMB) * A  (MMA)
+# * o       * o       * o
+# * o       * o       * o
+# * o       * o       * o
+# * o       | _______/
+# |         |/
+# |         * 1 (MM1)
+# | _______/
+# |/
+# * root (MMR)
+
+commit MMR
+commit MM1
+commit MM-o
+commit MM-p
+commit MM-q
+commit MMA
+git checkout MM1
+commit MM-r
+commit MM-s
+commit MM-t
+commit MMB
+git checkout MMR
+commit MM-u
+commit MM-v
+commit MM-w
+commit MM-x
+commit MMC
+
+{
+  baseline MMA MMB MMC
+} > 5_c.baseline
+
+merge () {
+  label="$1"
+  shift
+  tick
+  git merge -m "$label" "$@"
+  git tag "$label"
+}
+
+#             JE
+#            / |
+#           /  |
+#          /   |
+#  JAA    /    |
+#   |\   /     |
+#   | \  | JDD |
+#   |  \ |/ |  |
+#   |   JC JD  |
+#   |    | /|  |
+#   |    |/ |  |
+#  JA    |  |  |
+#   |\  /|  |  |
+#   X JB |  X  X
+#   \  \ | /   /
+#    \__\|/___/
+#        J
+commit J
+commit JB
+git reset --hard J
+commit JC
+git reset --hard J
+commit JTEMP1
+merge JA JB
+merge JAA JC
+git reset --hard J
+commit JTEMP2
+merge JD JB
+merge JDD JC
+git reset --hard J
+commit JTEMP3
+merge JE JC
+
+{
+  baseline JAA JDD JE
+} > 5_c.baseline
+
 git commit-graph write --no-progress --reachable
 git repack -adq