[PATCHv6 08/31] directory rename detection: testcases exploring possibly suboptimal merges
Signed-off-by: Elijah Newren <newren@gmail.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 38ca791e9..470c9a79f 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -1904,4 +1904,408 @@ 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
--
2.14.2
Elijah Newren <newren@gmail.com>