Collect merge-related tests to t64xx

The tests for the merge machinery are spread over several places.
Collect them into t64xx for simplicity.  Some notes:

t60[234]*.sh:
  Merge tests started in t602*, overgrew bisect and remote tracking
  tests in t6030, t6040, and t6041, and nearly overtook replace tests
  in t6050.  This made picking out relevant tests that I wanted to run
  in a tighter loop slightly more annoying for years.

t303*.sh:
  These started out as tests for the 'merge-recursive' toplevel command,
  but did not restrict to that and had lots of overlap with the
  underlying merge machinery.
t7405, t7613:
  submodule-specific merge logic started out in submodule.c but was
  moved to merge-recursive.c in commit 18cfc08866 ("submodule.c: move
  submodule merging to merge-recursive.c", 2018-05-15).  Since these
  tests are about the logic found in the merge machinery, moving these
  tests to be with the merge tests makes sense.

t7607, t7609:
  Having tests spread all over the place makes it more likely that
  additional tests related to a certain piece of logic grow in all those
  other places.  Much like t303*.sh, these two tests were about the
  underlying merge machinery rather than outer levels.

Tests that were NOT moved:

t76[01]*.sh:
  Other than the four tests mentioned above, the remaining tests in
  t76[01]*.sh are related to non-recursive merge strategies, parameter
  parsing, and other stuff associated with the highlevel builtin/merge.c
  rather than the recursive merge machinery.

t3[45]*.sh:
  The rebase testcases in t34*.sh also test the merge logic pretty
  heavily; sometimes changes I make only trigger failures in the rebase
  tests.  The rebase tests are already nicely coupled together, though,
  and I didn't want to mess that up.  Similar comments apply for the
  cherry-pick tests in t35*.sh.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 95 insertions, 0 deletions

diff --git a/t/t6431-merge-criscross.sh b/t/t6431-merge-criscross.sh
new file mode 100755
index 0000000..3824756
--- /dev/null
+++ b/t/t6431-merge-criscross.sh
@@ -0,0 +1,95 @@
+#!/bin/sh
+
+test_description='merge-recursive backend test'
+
+. ./test-lib.sh
+
+#         A      <- create some files
+#        / \
+#       B   C    <- cause rename/delete conflicts between B and C
+#      /     \
+#     |\     /|
+#     | D   E |
+#     |  \ /  |
+#     |   X   |
+#     |  / \  |
+#     | /   \ |
+#     |/     \|
+#     F       G  <- merge E into B, D into C
+#      \     /
+#       \   /
+#        \ /
+#         H      <- recursive merge crashes
+#
+
+# initialize
+test_expect_success 'setup repo with criss-cross history' '
+	mkdir data &&
+
+	# create a bunch of files
+	n=1 &&
+	while test $n -le 10
+	do
+		echo $n > data/$n &&
+		n=$(($n+1)) ||
+		return 1
+	done &&
+
+	# check them in
+	git add data &&
+	git commit -m A &&
+	git branch A &&
+
+	# a file in one branch
+	git checkout -b B A &&
+	git rm data/9 &&
+	git add data &&
+	git commit -m B &&
+
+	# with a branch off of it
+	git branch D &&
+
+	# put some commits on D
+	git checkout D &&
+	echo testD > data/testD &&
+	git add data &&
+	git commit -m D &&
+
+	# back up to the top, create another branch and cause
+	# a rename conflict with the file we deleted earlier
+	git checkout -b C A &&
+	git mv data/9 data/new-9 &&
+	git add data &&
+	git commit -m C &&
+
+	# with a branch off of it
+	git branch E &&
+
+	# put a commit on E
+	git checkout E &&
+	echo testE > data/testE &&
+	git add data &&
+	git commit -m E &&
+
+	# now, merge E into B
+	git checkout B &&
+	test_must_fail git merge E &&
+	# force-resolve
+	git add data &&
+	git commit -m F &&
+	git branch F &&
+
+	# and merge D into C
+	git checkout C &&
+	test_must_fail git merge D &&
+	# force-resolve
+	git add data &&
+	git commit -m G &&
+	git branch G
+'
+
+test_expect_success 'recursive merge between F and G does not cause segfault' '
+	git merge F
+'
+
+test_done