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From: Elijah Newren <newren@gmail.com>
To: git@vger.kernel.org
Cc: sbeller@google.com, gitster@pobox.com,
	torvalds@linux-foundation.org, Elijah Newren <newren@gmail.com>
Subject: [PATCH v10 08/36] directory rename detection: testcases exploring possibly suboptimal merges
Date: Thu, 19 Apr 2018 10:57:55 -0700	[thread overview]
Message-ID: <20180419175823.7946-9-newren@gmail.com> (raw)
In-Reply-To: <20180419175823.7946-1-newren@gmail.com>

Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 t/t6043-merge-rename-directories.sh | 404 ++++++++++++++++++++++++++++
 1 file changed, 404 insertions(+)

diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
index 6db1439675..e211e8ca31 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -1912,4 +1912,408 @@ test_expect_failure '7e-check: transitive rename in rename/delete AND dirs in th
 	)
 '
 
+###########################################################################
+# SECTION 8: Suboptimal merges
+#
+# As alluded to in the last section, the ruleset we have built up for
+# detecting directory renames unfortunately has some special cases where it
+# results in slightly suboptimal or non-intuitive behavior.  This section
+# explores these cases.
+#
+# To be fair, we already had non-intuitive or suboptimal behavior for most
+# of these cases in git before introducing implicit directory rename
+# detection, but it'd be nice if there was a modified ruleset out there
+# that handled these cases a bit better.
+###########################################################################
+
+# Testcase 8a, Dual-directory rename, one into the others' way
+#   Commit O. x/{a,b},   y/{c,d}
+#   Commit A. x/{a,b,e}, y/{c,d,f}
+#   Commit B. y/{a,b},   z/{c,d}
+#
+# Possible Resolutions:
+#   w/o dir-rename detection: y/{a,b,f},   z/{c,d},   x/e
+#   Currently expected:       y/{a,b,e,f}, z/{c,d}
+#   Optimal:                  y/{a,b,e},   z/{c,d,f}
+#
+# Note: Both x and y got renamed and it'd be nice to detect both, and we do
+# better with directory rename detection than git did without, but the
+# simple rule from section 5 prevents me from handling this as optimally as
+# we potentially could.
+
+test_expect_success '8a-setup: Dual-directory rename, one into the others way' '
+	test_create_repo 8a &&
+	(
+		cd 8a &&
+
+		mkdir x &&
+		mkdir y &&
+		echo a >x/a &&
+		echo b >x/b &&
+		echo c >y/c &&
+		echo d >y/d &&
+		git add x y &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		echo e >x/e &&
+		echo f >y/f &&
+		git add x/e y/f &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv y z &&
+		git mv x y &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '8a-check: Dual-directory rename, one into the others way' '
+	(
+		cd 8a &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		git ls-files -s >out &&
+		test_line_count = 6 out &&
+		git ls-files -u >out &&
+		test_line_count = 0 out &&
+		git ls-files -o >out &&
+		test_line_count = 1 out &&
+
+		git rev-parse >actual \
+			HEAD:y/a HEAD:y/b HEAD:y/e HEAD:y/f HEAD:z/c HEAD:z/d &&
+		git rev-parse >expect \
+			O:x/a    O:x/b    A:x/e    A:y/f    O:y/c    O:y/d &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 8b, Dual-directory rename, one into the others' way, with conflicting filenames
+#   Commit O. x/{a_1,b_1},     y/{a_2,b_2}
+#   Commit A. x/{a_1,b_1,e_1}, y/{a_2,b_2,e_2}
+#   Commit B. y/{a_1,b_1},     z/{a_2,b_2}
+#
+#   w/o dir-rename detection: y/{a_1,b_1,e_2}, z/{a_2,b_2}, x/e_1
+#   Currently expected:       <same>
+#   Scary:                    y/{a_1,b_1},     z/{a_2,b_2}, CONFLICT(add/add, e_1 vs. e_2)
+#   Optimal:                  y/{a_1,b_1,e_1}, z/{a_2,b_2,e_2}
+#
+# Note: Very similar to 8a, except instead of 'e' and 'f' in directories x and
+# y, both are named 'e'.  Without directory rename detection, neither file
+# moves directories.  Implement directory rename detection suboptimally, and
+# you get an add/add conflict, but both files were added in commit A, so this
+# is an add/add conflict where one side of history added both files --
+# something we can't represent in the index.  Obviously, we'd prefer the last
+# resolution, but our previous rules are too coarse to allow it.  Using both
+# the rules from section 4 and section 5 save us from the Scary resolution,
+# making us fall back to pre-directory-rename-detection behavior for both
+# e_1 and e_2.
+
+test_expect_success '8b-setup: Dual-directory rename, one into the others way, with conflicting filenames' '
+	test_create_repo 8b &&
+	(
+		cd 8b &&
+
+		mkdir x &&
+		mkdir y &&
+		echo a1 >x/a &&
+		echo b1 >x/b &&
+		echo a2 >y/a &&
+		echo b2 >y/b &&
+		git add x y &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		echo e1 >x/e &&
+		echo e2 >y/e &&
+		git add x/e y/e &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv y z &&
+		git mv x y &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_success '8b-check: Dual-directory rename, one into the others way, with conflicting filenames' '
+	(
+		cd 8b &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		git ls-files -s >out &&
+		test_line_count = 6 out &&
+		git ls-files -u >out &&
+		test_line_count = 0 out &&
+		git ls-files -o >out &&
+		test_line_count = 1 out &&
+
+		git rev-parse >actual \
+			HEAD:y/a HEAD:y/b HEAD:z/a HEAD:z/b HEAD:x/e HEAD:y/e &&
+		git rev-parse >expect \
+			O:x/a    O:x/b    O:y/a    O:y/b    A:x/e    A:y/e &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 8c, rename+modify/delete
+#   (Related to testcases 5b and 8d)
+#   Commit O: z/{b,c,d}
+#   Commit A: y/{b,c}
+#   Commit B: z/{b,c,d_modified,e}
+#   Expected: y/{b,c,e}, CONFLICT(rename+modify/delete: x/d -> y/d or deleted)
+#
+#   Note: This testcase doesn't present any concerns for me...until you
+#         compare it with testcases 5b and 8d.  See notes in 8d for more
+#         details.
+
+test_expect_success '8c-setup: rename+modify/delete' '
+	test_create_repo 8c &&
+	(
+		cd 8c &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		test_seq 1 10 >z/d &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git rm z/d &&
+		git mv z y &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		echo 11 >z/d &&
+		test_chmod +x z/d &&
+		echo e >z/e &&
+		git add z/d z/e &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '8c-check: rename+modify/delete' '
+	(
+		cd 8c &&
+
+		git checkout A^0 &&
+
+		test_must_fail git merge -s recursive B^0 >out &&
+		test_i18ngrep "CONFLICT (rename/delete).* z/d.*y/d" out &&
+
+		git ls-files -s >out &&
+		test_line_count = 4 out &&
+		git ls-files -u >out &&
+		test_line_count = 1 out &&
+		git ls-files -o >out &&
+		test_line_count = 1 out &&
+
+		git rev-parse >actual \
+			:0:y/b :0:y/c :0:y/e :3:y/d &&
+		git rev-parse >expect \
+			 O:z/b  O:z/c  B:z/e  B:z/d &&
+		test_cmp expect actual &&
+
+		test_must_fail git rev-parse :1:y/d &&
+		test_must_fail git rev-parse :2:y/d &&
+		git ls-files -s y/d | grep ^100755 &&
+		test_path_is_file y/d
+	)
+'
+
+# Testcase 8d, rename/delete...or not?
+#   (Related to testcase 5b; these may appear slightly inconsistent to users;
+#    Also related to testcases 7d and 7e)
+#   Commit O: z/{b,c,d}
+#   Commit A: y/{b,c}
+#   Commit B: z/{b,c,d,e}
+#   Expected: y/{b,c,e}
+#
+#   Note: It would also be somewhat reasonable to resolve this as
+#             y/{b,c,e}, CONFLICT(rename/delete: x/d -> y/d or deleted)
+#   The logic being that the only difference between this testcase and 8c
+#   is that there is no modification to d.  That suggests that instead of a
+#   rename/modify vs. delete conflict, we should just have a rename/delete
+#   conflict, otherwise we are being inconsistent.
+#
+#   However...as far as consistency goes, we didn't report a conflict for
+#   path d_1 in testcase 5b due to a different file being in the way.  So,
+#   we seem to be forced to have cases where users can change things
+#   slightly and get what they may perceive as inconsistent results.  It
+#   would be nice to avoid that, but I'm not sure I see how.
+#
+#   In this case, I'm leaning towards: commit A was the one that deleted z/d
+#   and it did the rename of z to y, so the two "conflicts" (rename vs.
+#   delete) are both coming from commit A, which is illogical.  Conflicts
+#   during merging are supposed to be about opposite sides doing things
+#   differently.
+
+test_expect_success '8d-setup: rename/delete...or not?' '
+	test_create_repo 8d &&
+	(
+		cd 8d &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		test_seq 1 10 >z/d &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git rm z/d &&
+		git mv z y &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		echo e >z/e &&
+		git add z/e &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '8d-check: rename/delete...or not?' '
+	(
+		cd 8d &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		git ls-files -s >out &&
+		test_line_count = 3 out &&
+
+		git rev-parse >actual \
+			HEAD:y/b HEAD:y/c HEAD:y/e &&
+		git rev-parse >expect \
+			O:z/b    O:z/c    B:z/e &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 8e, Both sides rename, one side adds to original directory
+#   Commit O: z/{b,c}
+#   Commit A: y/{b,c}
+#   Commit B: w/{b,c}, z/d
+#
+# Possible Resolutions:
+#   w/o dir-rename detection: z/d, CONFLICT(z/b -> y/b vs. w/b),
+#                                  CONFLICT(z/c -> y/c vs. w/c)
+#   Currently expected:       y/d, CONFLICT(z/b -> y/b vs. w/b),
+#                                  CONFLICT(z/c -> y/c vs. w/c)
+#   Optimal:                  ??
+#
+# Notes: In commit A, directory z got renamed to y.  In commit B, directory z
+#        did NOT get renamed; the directory is still present; instead it is
+#        considered to have just renamed a subset of paths in directory z
+#        elsewhere.  Therefore, the directory rename done in commit A to z/
+#        applies to z/d and maps it to y/d.
+#
+#        It's possible that users would get confused about this, but what
+#        should we do instead?  Silently leaving at z/d seems just as bad or
+#        maybe even worse.  Perhaps we could print a big warning about z/d
+#        and how we're moving to y/d in this case, but when I started thinking
+#        about the ramifications of doing that, I didn't know how to rule out
+#        that opening other weird edge and corner cases so I just punted.
+
+test_expect_success '8e-setup: Both sides rename, one side adds to original directory' '
+	test_create_repo 8e &&
+	(
+		cd 8e &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z y &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv z w &&
+		mkdir z &&
+		echo d >z/d &&
+		git add z/d &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '8e-check: Both sides rename, one side adds to original directory' '
+	(
+		cd 8e &&
+
+		git checkout A^0 &&
+
+		test_must_fail git merge -s recursive B^0 >out 2>err &&
+		test_i18ngrep CONFLICT.*rename/rename.*z/c.*y/c.*w/c out &&
+		test_i18ngrep CONFLICT.*rename/rename.*z/b.*y/b.*w/b out &&
+
+		git ls-files -s >out &&
+		test_line_count = 7 out &&
+		git ls-files -u >out &&
+		test_line_count = 6 out &&
+		git ls-files -o >out &&
+		test_line_count = 2 out &&
+
+		git rev-parse >actual \
+			:1:z/b :2:y/b :3:w/b :1:z/c :2:y/c :3:w/c :0:y/d &&
+		git rev-parse >expect \
+			 O:z/b  O:z/b  O:z/b  O:z/c  O:z/c  O:z/c  B:z/d &&
+		test_cmp expect actual &&
+
+		git hash-object >actual \
+			y/b   w/b   y/c   w/c &&
+		git rev-parse >expect \
+			O:z/b O:z/b O:z/c O:z/c &&
+		test_cmp expect actual &&
+
+		test_path_is_missing z/b &&
+		test_path_is_missing z/c
+	)
+'
+
 test_done
-- 
2.17.0.290.ge988e9ce2a


  parent reply	other threads:[~2018-04-19 18:01 UTC|newest]

Thread overview: 78+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-19 17:57 [PATCH v10 00/36] Add directory rename detection to git Elijah Newren
2018-04-19 17:57 ` [PATCH v10 01/36] directory rename detection: basic testcases Elijah Newren
2018-04-19 17:57 ` [PATCH v10 02/36] directory rename detection: directory splitting testcases Elijah Newren
2018-04-19 17:57 ` [PATCH v10 03/36] directory rename detection: testcases to avoid taking detection too far Elijah Newren
2018-04-19 17:57 ` [PATCH v10 04/36] directory rename detection: partially renamed directory testcase/discussion Elijah Newren
2018-04-19 17:57 ` [PATCH v10 05/36] directory rename detection: files/directories in the way of some renames Elijah Newren
2018-04-19 17:57 ` [PATCH v10 06/36] directory rename detection: testcases checking which side did the rename Elijah Newren
2018-04-19 17:57 ` [PATCH v10 07/36] directory rename detection: more involved edge/corner testcases Elijah Newren
2018-04-19 17:57 ` Elijah Newren [this message]
2018-04-19 17:57 ` [PATCH v10 09/36] directory rename detection: miscellaneous testcases to complete coverage Elijah Newren
2018-04-19 17:57 ` [PATCH v10 10/36] directory rename detection: tests for handling overwriting untracked files Elijah Newren
2018-04-19 17:57 ` [PATCH v10 11/36] directory rename detection: tests for handling overwriting dirty files Elijah Newren
2018-04-19 17:57 ` [PATCH v10 12/36] merge-recursive: move the get_renames() function Elijah Newren
2018-04-19 17:58 ` [PATCH v10 13/36] merge-recursive: introduce new functions to handle rename logic Elijah Newren
2018-04-19 17:58 ` [PATCH v10 14/36] merge-recursive: fix leaks of allocated renames and diff_filepairs Elijah Newren
2018-04-19 17:58 ` [PATCH v10 15/36] merge-recursive: make !o->detect_rename codepath more obvious Elijah Newren
2018-04-19 17:58 ` [PATCH v10 16/36] merge-recursive: split out code for determining diff_filepairs Elijah Newren
2018-04-19 17:58 ` [PATCH v10 17/36] merge-recursive: make a helper function for cleanup for handle_renames Elijah Newren
2018-04-19 17:58 ` [PATCH v10 18/36] merge-recursive: add get_directory_renames() Elijah Newren
2018-05-06 23:41   ` SZEDER Gábor
2018-05-07 15:45     ` [PATCH] fixup! " Elijah Newren
2019-10-09 20:38   ` [PATCH v10 18/36] " Johannes Schindelin
2019-10-11 20:02     ` Elijah Newren
2019-10-12 19:23       ` Johannes Schindelin
2018-04-19 17:58 ` [PATCH v10 19/36] merge-recursive: check for directory level conflicts Elijah Newren
2018-04-19 17:58 ` [PATCH v10 20/36] merge-recursive: add computation of collisions due to dir rename & merging Elijah Newren
2018-04-19 17:58 ` [PATCH v10 21/36] merge-recursive: check for file level conflicts then get new name Elijah Newren
2018-04-19 17:58 ` [PATCH v10 22/36] merge-recursive: when comparing files, don't include trees Elijah Newren
2018-04-19 17:58 ` [PATCH v10 23/36] merge-recursive: apply necessary modifications for directory renames Elijah Newren
2018-04-19 17:58 ` [PATCH v10 24/36] merge-recursive: avoid clobbering untracked files with " Elijah Newren
2018-04-19 17:58 ` [PATCH v10 25/36] merge-recursive: fix overwriting dirty files involved in renames Elijah Newren
2018-04-19 20:48   ` Martin Ågren
2018-04-19 20:54     ` Martin Ågren
2018-04-19 21:06     ` Elijah Newren
2018-04-19 17:58 ` [PATCH v10 26/36] merge-recursive: fix remaining directory rename + dirty overwrite cases Elijah Newren
2018-04-19 17:58 ` [PATCH v10 27/36] directory rename detection: new testcases showcasing a pair of bugs Elijah Newren
2018-04-19 17:58 ` [PATCH v10 28/36] merge-recursive: avoid spurious rename/rename conflict from dir renames Elijah Newren
2018-04-19 17:58 ` [PATCH v10 29/36] merge-recursive: improve add_cacheinfo error handling Elijah Newren
2018-04-19 17:58 ` [PATCH v10 30/36] merge-recursive: move more is_dirty handling to merge_content Elijah Newren
2018-04-19 17:58 ` [PATCH v10 31/36] merge-recursive: avoid triggering add_cacheinfo error with dirty mod Elijah Newren
2018-04-19 17:58 ` [PATCH v10 32/36] t6046: testcases checking whether updates can be skipped in a merge Elijah Newren
2018-04-19 20:26   ` SZEDER Gábor
2018-04-19 20:55     ` Elijah Newren
2018-04-19 17:58 ` [PATCH v10 33/36] merge-recursive: fix was_tracked() to quit lying with some renamed paths Elijah Newren
2018-04-19 20:39   ` Martin Ågren
2018-04-19 20:54     ` Elijah Newren
2018-04-20 12:23   ` SZEDER Gábor
2018-04-20 15:23     ` Elijah Newren
2018-04-21 19:37     ` [RFC PATCH v10 32.5/36] unpack_trees: fix memory corruption with split_index when src != dst Elijah Newren
2018-04-21 20:13       ` Elijah Newren
2018-04-22 12:38       ` Duy Nguyen
2018-04-23 17:09         ` Elijah Newren
2018-04-23 17:37           ` Duy Nguyen
2018-04-23 18:05             ` Elijah Newren
2018-04-24  0:24               ` [PATCH v2] unpack_trees: fix breakage when o->src_index != o->dst_index Elijah Newren
2018-04-24  1:51                 ` Junio C Hamano
2018-04-24  3:05                 ` Junio C Hamano
2018-04-24  6:50                   ` [PATCH v3] " Elijah Newren
2018-04-29 18:05                     ` Duy Nguyen
2018-04-29 20:53                       ` Johannes Schindelin
2018-04-30 14:42                         ` Duy Nguyen
2018-04-30 14:45                           ` Duy Nguyen
2018-04-30 16:19                             ` Elijah Newren
2018-04-30 16:29                               ` Duy Nguyen
2018-04-19 17:58 ` [PATCH v10 34/36] merge-recursive: fix remainder of was_dirty() to use original index Elijah Newren
2018-04-19 17:58 ` [PATCH v10 35/36] merge-recursive: make "Auto-merging" comment show for other merges Elijah Newren
2018-04-19 17:58 ` [PATCH v10 36/36] merge-recursive: fix check for skipability of working tree updates Elijah Newren
2018-04-19 18:35 ` [PATCH v10 00/36] Add directory rename detection to git Elijah Newren
2018-04-19 18:41   ` Stefan Beller
2018-04-19 19:54     ` Derrick Stolee
2018-04-19 20:22   ` Elijah Newren
2018-04-20  3:05   ` Junio C Hamano
2018-04-23 17:50     ` Elijah Newren
2018-04-24 20:20     ` [PATCH v10 1/2] fixup! merge-recursive: fix was_tracked() to quit lying with some renamed paths Elijah Newren
2018-04-24 20:21       ` [PATCH v10 2/2] fixup! t6046: testcases checking whether updates can be skipped in a merge Elijah Newren
2018-04-23 17:28 ` [PATCH v10 00/36] Add directory rename detection to git Elijah Newren
2018-04-23 23:46   ` Junio C Hamano
2018-04-24  0:15     ` Elijah Newren

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