+# We test the overflow-related code with the following repo history:
+#
+# 4:F - 5:N - 6:U
+# / \
+# 1:U - 2:N - 3:U M:N
+# \ /
+# 7:N - 8:F - 9:N
+#
+# Here the commits denoted by U have committer date of zero seconds
+# since Unix epoch, the commits denoted by N have committer date
+# starting from 1112354055 seconds since Unix epoch (default committer
+# date for the test suite), and the commits denoted by F have committer
+# date of (2 ^ 31 - 2) seconds since Unix epoch.
+#
+# The largest offset observed is 2 ^ 31, just large enough to overflow.
+#
+
+test_expect_success 'set up and verify repo with generation data overflow chunk' '
+ objdir=".git/objects" &&
+ UNIX_EPOCH_ZERO="@0 +0000" &&
+ FUTURE_DATE="@2147483646 +0000" &&
+ test_oid_cache <<-EOF &&
+ oid_version sha1:1
+ oid_version sha256:2
+ EOF
+ cd "$TRASH_DIRECTORY" &&
+ mkdir repo &&
+ cd repo &&
+ git init &&
+ test_commit --date "$UNIX_EPOCH_ZERO" 1 &&
+ test_commit 2 &&
+ test_commit --date "$UNIX_EPOCH_ZERO" 3 &&
+ git commit-graph write --reachable &&
+ graph_read_expect 3 generation_data &&
+ test_commit --date "$FUTURE_DATE" 4 &&
+ test_commit 5 &&
+ test_commit --date "$UNIX_EPOCH_ZERO" 6 &&
+ git branch left &&
+ git reset --hard 3 &&
+ test_commit 7 &&
+ test_commit --date "$FUTURE_DATE" 8 &&
+ test_commit 9 &&
+ git branch right &&
+ git reset --hard 3 &&
+ test_merge M left right &&
+ git commit-graph write --reachable &&
+ graph_read_expect 10 "generation_data generation_data_overflow" &&
+ git commit-graph verify
+'
+
+graph_git_behavior 'generation data overflow chunk repo' repo left right
+