t6042: Ensure rename/rename conflicts leave index and workdir in sane state

rename/rename conflicts, both with one file being renamed to two different
files and with two files being renamed to the same file, should leave the
index and the working copy in a sane state with appropriate conflict
recording, auxiliary files, etc.  Git seems to handle one of the two cases
alright, but has some problems with the two files being renamed to one
case.  Add tests for both cases.

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

1 files changed, 102 insertions, 0 deletions

diff --git a/t/t6042-merge-rename-corner-cases.sh b/t/t6042-merge-rename-corner-cases.sh
index b46566744..371fb39c6 100755
--- a/t/t6042-merge-rename-corner-cases.sh
+++ b/t/t6042-merge-rename-corner-cases.sh
@@ -339,4 +339,106 @@ test_expect_success 'disappearing dir in rename/directory conflict handled' '
 	test -f sub
 '
 
+# Test for all kinds of things that can go wrong with rename/rename (2to1):
+#   Commit A: new files: a & b
+#   Commit B: rename a->c, modify b
+#   Commit C: rename b->c, modify a
+#
+# Merging of B & C should NOT be clean.  Questions:
+#   * Both a & b should be removed by the merge; are they?
+#   * The two c's should contain modifications to a & b; do they?
+#   * The index should contain two files, both for c; does it?
+#   * The working copy should have two files, both of form c~<unique>; does it?
+#   * Nothing else should be present.  Is anything?
+
+test_expect_success 'setup rename/rename (2to1) + modify/modify' '
+	git rm -rf . &&
+	git clean -fdqx &&
+	rm -rf .git &&
+	git init &&
+
+	printf "1\n2\n3\n4\n5\n" >a &&
+	printf "5\n4\n3\n2\n1\n" >b &&
+	git add a b &&
+	git commit -m A &&
+	git tag A &&
+
+	git checkout -b B A &&
+	git mv a c &&
+	echo 0 >>b &&
+	git add b &&
+	git commit -m B &&
+
+	git checkout -b C A &&
+	git mv b c &&
+	echo 6 >>a &&
+	git add a &&
+	git commit -m C
+'
+
+test_expect_failure 'handle rename/rename (2to1) conflict correctly' '
+	git checkout B^0 &&
+
+	test_must_fail git merge -s recursive C^0 >out &&
+	grep "CONFLICT (rename/rename)" out &&
+
+	test 2 -eq $(git ls-files -s | wc -l) &&
+	test 2 -eq $(git ls-files -u | wc -l) &&
+	test 2 -eq $(git ls-files -u c | wc -l) &&
+	test 3 -eq $(git ls-files -o | wc -l) &&
+
+	test ! -f a &&
+	test ! -f b &&
+	test -f c~HEAD &&
+	test -f c~C^0 &&
+
+	test $(git hash-object c~HEAD) = $(git rev-parse C:a) &&
+	test $(git hash-object c~C^0) = $(git rev-parse B:b)
+'
+
+# Testcase setup for simple rename/rename (1to2) conflict:
+#   Commit A: new file: a
+#   Commit B: rename a->b
+#   Commit C: rename a->c
+test_expect_success 'setup simple rename/rename (1to2) conflict' '
+	git rm -rf . &&
+	git clean -fdqx &&
+	rm -rf .git &&
+	git init &&
+
+	echo stuff >a &&
+	git add a &&
+	test_tick &&
+	git commit -m A &&
+	git tag A &&
+
+	git checkout -b B A &&
+	git mv a b &&
+	test_tick &&
+	git commit -m B &&
+
+	git checkout -b C A &&
+	git mv a c &&
+	test_tick &&
+	git commit -m C
+'
+
+test_expect_success 'merge has correct working tree contents' '
+	git checkout C^0 &&
+
+	test_must_fail git merge -s recursive B^0 &&
+
+	test 3 -eq $(git ls-files -s | wc -l) &&
+	test 3 -eq $(git ls-files -u | wc -l) &&
+	test 0 -eq $(git ls-files -o | wc -l) &&
+
+	test $(git rev-parse :1:a) = $(git rev-parse A:a) &&
+	test $(git rev-parse :3:b) = $(git rev-parse A:a) &&
+	test $(git rev-parse :2:c) = $(git rev-parse A:a) &&
+
+	test ! -f a &&
+	test $(git hash-object b) = $(git rev-parse A:a) &&
+	test $(git hash-object c) = $(git rev-parse A:a)
+'
+
 test_done