t6042: Add failing testcases for rename/rename/add-{source,dest} conflicts

Add testcases that cover three failures with current git merge, all
involving renaming one file on both sides of history:

Case 1:
If a single file is renamed to two different filenames on different sides
of history, there should be a conflict.  Adding a new file on one of those
sides of history whose name happens to match the rename source should not
cause the merge to suddenly succeed.

Case 2:
If a single file is renamed on both sides of history but renamed
identically, there should not be a conflict.  This works fine.  However,
if one of those sides also added a new file that happened to match the
rename source, then that file should be left alone.  Currently, the
rename/rename conflict handling causes that new file to become untracked.

Case 3:
If a single file is renamed to two different filenames on different sides
of history, there should be a conflict.  This works currently.  However,
if those renames also involve rename/add conflicts (i.e. there are new
files on one side of history that match the destination of the rename of
the other side of history), then the resulting conflict should be recorded
in the index, showing that there were multiple files with a given filename.
Currently, git silently discards one of file versions.

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

diff --git a/t/t6042-merge-rename-corner-cases.sh b/t/t6042-merge-rename-corner-cases.sh
index 371fb39c6a51f33f0b980d4dac8dc50555c15c1d..427fe1c913161b27107fe86de0ea419473061bc0 100755 (executable)
--- a/t/t6042-merge-rename-corner-cases.sh
+++ b/t/t6042-merge-rename-corner-cases.sh
@@ -441,4 +441,129 @@ test_expect_success 'merge has correct working tree contents' '
        test $(git hash-object c) = $(git rev-parse A:a)
 '
 
+# Testcase setup for rename/rename(1to2)/add-source conflict:
+#   Commit A: new file: a
+#   Commit B: rename a->b
+#   Commit C: rename a->c, add completely different a
+#
+# Merging of B & C should NOT be clean; there's a rename/rename conflict
+
+test_expect_success 'setup rename/rename(1to2)/add-source conflict' '
+       git rm -rf . &&
+       git clean -fdqx &&
+       rm -rf .git &&
+       git init &&
+
+       printf "1\n2\n3\n4\n5\n6\n7\n" >a &&
+       git add a &&
+       git commit -m A &&
+       git tag A &&
+
+       git checkout -b B A &&
+       git mv a b &&
+       git commit -m B &&
+
+       git checkout -b C A &&
+       git mv a c &&
+       echo something completely different >a &&
+       git add a &&
+       git commit -m C
+'
+
+test_expect_failure 'detect conflict with rename/rename(1to2)/add-source merge' '
+       git checkout B^0 &&
+
+       test_must_fail git merge -s recursive C^0 &&
+
+       test 4 -eq $(git ls-files -s | wc -l) &&
+       test 0 -eq $(git ls-files -o | wc -l) &&
+
+       test $(git rev-parse 3:a) = $(git rev-parse C:a) &&
+       test $(git rev-parse 1:a) = $(git rev-parse A:a) &&
+       test $(git rev-parse 2:b) = $(git rev-parse B:b) &&
+       test $(git rev-parse 3:c) = $(git rev-parse C:c) &&
+
+       test -f a &&
+       test -f b &&
+       test -f c
+'
+
+test_expect_success 'setup rename/rename(1to2)/add-source resolvable conflict' '
+       git rm -rf . &&
+       git clean -fdqx &&
+       rm -rf .git &&
+       git init &&
+
+       >a &&
+       git add a &&
+       test_tick &&
+       git commit -m base &&
+       git tag A &&
+
+       git checkout -b B A &&
+       git mv a b &&
+       test_tick &&
+       git commit -m one &&
+
+       git checkout -b C A &&
+       git mv a b &&
+       echo important-info >a &&
+       git add a &&
+       test_tick &&
+       git commit -m two
+'
+
+test_expect_failure 'rename/rename/add-source still tracks new a file' '
+       git checkout C^0 &&
+       git merge -s recursive B^0 &&
+
+       test 2 -eq $(git ls-files -s | wc -l) &&
+       test 0 -eq $(git ls-files -o | wc -l) &&
+
+       test $(git rev-parse HEAD:a) = $(git rev-parse C:a) &&
+       test $(git rev-parse HEAD:b) = $(git rev-parse A:a)
+'
+
+test_expect_success 'setup rename/rename(1to2)/add-dest conflict' '
+       git rm -rf . &&
+       git clean -fdqx &&
+       rm -rf .git &&
+       git init &&
+
+       echo stuff >a &&
+       git add a &&
+       test_tick &&
+       git commit -m base &&
+       git tag A &&
+
+       git checkout -b B A &&
+       git mv a b &&
+       echo precious-data >c &&
+       git add c &&
+       test_tick &&
+       git commit -m one &&
+
+       git checkout -b C A &&
+       git mv a c &&
+       echo important-info >b &&
+       git add b &&
+       test_tick &&
+       git commit -m two
+'
+
+test_expect_failure 'rename/rename/add-dest merge still knows about conflicting file versions' '
+       git checkout C^0 &&
+       test_must_fail git merge -s recursive B^0 &&
+
+       test 5 -eq $(git ls-files -s | wc -l) &&
+       test 2 -eq $(git ls-files -u b | wc -l) &&
+       test 2 -eq $(git ls-files -u c | wc -l) &&
+
+       test $(git rev-parse :1:a) = $(git rev-parse A:a) &&
+       test $(git rev-parse :2:b) = $(git rev-parse C:b) &&
+       test $(git rev-parse :3:b) = $(git rev-parse B:b) &&
+       test $(git rev-parse :2:c) = $(git rev-parse C:c) &&
+       test $(git rev-parse :3:c) = $(git rev-parse B:c)
+'
+
 test_done