t6036, t6042: testcases for rename collision of already conflicting files

When a single file is renamed, it can also be modified, yielding the
possibility of that renamed file having content conflicts.  If two
different such files are renamed into the same location, then two-way
merging those files may result in nested conflicts.  Add a testcase that
makes sure we get this case correct, and uses different lengths of
conflict markers to differentiate between the different nestings.

Also add another case with an extra (i.e. third) level of conflict
markers due to using merge.conflictstyle=diff3 and the virtual merge
base also having conflicts present.

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

1 files changed, 194 insertions, 0 deletions

diff --git a/t/t6036-recursive-corner-cases.sh b/t/t6036-recursive-corner-cases.sh
index e1cef58..f229d7e 100755
--- a/t/t6036-recursive-corner-cases.sh
+++ b/t/t6036-recursive-corner-cases.sh
@@ -1402,4 +1402,198 @@ test_expect_failure 'check conflicting modes for regular file' '
 	)
 '
 
+# Setup:
+#          L1---L2
+#         /  \ /  \
+#   master    X    ?
+#         \  / \  /
+#          R1---R2
+#
+# Where:
+#   master has two files, named 'b' and 'a'
+#   branches L1 and R1 both modify each of the two files in conflicting ways
+#
+#   L2 is a merge of R1 into L1; more on it later.
+#   R2 is a merge of L1 into R1; more on it later.
+#
+#   X is an auto-generated merge-base used when merging L2 and R2.
+#   since X is a merge of L1 and R1, it has conflicting versions of each file
+#
+#   More about L2 and R2:
+#     - both resolve the conflicts in 'b' and 'a' differently
+#     - L2 renames 'b' to 'm'
+#     - R2 renames 'a' to 'm'
+#
+#   In the end, in file 'm' we have four different conflicting files (from
+#   two versions of 'b' and two of 'a').  In addition, if
+#   merge.conflictstyle is diff3, then the base version also has
+#   conflict markers of its own, leading to a total of three levels of
+#   conflict markers.  This is a pretty weird corner case, but we just want
+#   to ensure that we handle it as well as practical.
+
+test_expect_success 'setup nested conflicts' '
+	test_create_repo nested_conflicts &&
+	(
+		cd nested_conflicts &&
+
+		# Create some related files now
+		for i in $(test_seq 1 10)
+		do
+			echo Random base content line $i
+		done >initial &&
+
+		cp initial b_L1 &&
+		cp initial b_R1 &&
+		cp initial b_L2 &&
+		cp initial b_R2 &&
+		cp initial a_L1 &&
+		cp initial a_R1 &&
+		cp initial a_L2 &&
+		cp initial a_R2 &&
+
+		test_write_lines b b_L1 >>b_L1 &&
+		test_write_lines b b_R1 >>b_R1 &&
+		test_write_lines b b_L2 >>b_L2 &&
+		test_write_lines b b_R2 >>b_R2 &&
+		test_write_lines a a_L1 >>a_L1 &&
+		test_write_lines a a_R1 >>a_R1 &&
+		test_write_lines a a_L2 >>a_L2 &&
+		test_write_lines a a_R2 >>a_R2 &&
+
+		# Setup original commit (or merge-base), consisting of
+		# files named "b" and "a"
+		cp initial b &&
+		cp initial a &&
+		echo b >>b &&
+		echo a >>a &&
+		git add b a &&
+		test_tick && git commit -m initial &&
+
+		git branch L &&
+		git branch R &&
+
+		# Handle the left side
+		git checkout L &&
+		mv -f b_L1 b &&
+		mv -f a_L1 a &&
+		git add b a &&
+		test_tick && git commit -m "version L1 of files" &&
+		git tag L1 &&
+
+		# Handle the right side
+		git checkout R &&
+		mv -f b_R1 b &&
+		mv -f a_R1 a &&
+		git add b a &&
+		test_tick && git commit -m "verson R1 of files" &&
+		git tag R1 &&
+
+		# Create first merge on left side
+		git checkout L &&
+		test_must_fail git merge R1 &&
+		mv -f b_L2 b &&
+		mv -f a_L2 a &&
+		git add b a &&
+		git mv b m &&
+		test_tick && git commit -m "left merge, rename b->m" &&
+		git tag L2 &&
+
+		# Create first merge on right side
+		git checkout R &&
+		test_must_fail git merge L1 &&
+		mv -f b_R2 b &&
+		mv -f a_R2 a &&
+		git add b a &&
+		git mv a m &&
+		test_tick && git commit -m "right merge, rename a->m" &&
+		git tag R2
+	)
+'
+
+test_expect_failure 'check nested conflicts' '
+	(
+		cd nested_conflicts &&
+
+		git clean -f &&
+		git checkout L2^0 &&
+
+		# Merge must fail; there is a conflict
+		test_must_fail git -c merge.conflictstyle=diff3 merge -s recursive R2^0 &&
+
+		# Make sure the index has the right number of entries
+		git ls-files -s >out &&
+		test_line_count = 2 out &&
+		git ls-files -u >out &&
+		test_line_count = 2 out &&
+		# Ensure we have the correct number of untracked files
+		git ls-files -o >out &&
+		test_line_count = 1 out &&
+
+		# Create a and b from virtual merge base X
+		git cat-file -p master:a >base &&
+		git cat-file -p L1:a >ours &&
+		git cat-file -p R1:a >theirs &&
+		test_must_fail git merge-file --diff3 \
+			-L "Temporary merge branch 1" \
+			-L "merged common ancestors"  \
+			-L "Temporary merge branch 2" \
+			ours  \
+			base  \
+			theirs &&
+		sed -e "s/^\([<|=>]\)/\1\1/" ours >vmb_a &&
+
+		git cat-file -p master:b >base &&
+		git cat-file -p L1:b >ours &&
+		git cat-file -p R1:b >theirs &&
+		test_must_fail git merge-file --diff3 \
+			-L "Temporary merge branch 1" \
+			-L "merged common ancestors"  \
+			-L "Temporary merge branch 2" \
+			ours  \
+			base  \
+			theirs &&
+		sed -e "s/^\([<|=>]\)/\1\1/" ours >vmb_b &&
+
+		# Compare :2:m to expected values
+		git cat-file -p L2:m >ours &&
+		git cat-file -p R2:b >theirs &&
+		test_must_fail git merge-file --diff3  \
+			-L "HEAD:m"                    \
+			-L "merged common ancestors:b" \
+			-L "R2^0:b"                    \
+			ours                           \
+			vmb_b                          \
+			theirs                         &&
+		sed -e "s/^\([<|=>]\)/\1\1/" ours >m_stage_2 &&
+		git cat-file -p :2:m >actual &&
+		test_cmp m_stage_2 actual &&
+
+		# Compare :3:m to expected values
+		git cat-file -p L2:a >ours &&
+		git cat-file -p R2:m >theirs &&
+		test_must_fail git merge-file --diff3  \
+			-L "HEAD:a"                    \
+			-L "merged common ancestors:a" \
+			-L "R2^0:m"                    \
+			ours                           \
+			vmb_a                          \
+			theirs                         &&
+		sed -e "s/^\([<|=>]\)/\1\1/" ours >m_stage_3 &&
+		git cat-file -p :3:m >actual &&
+		test_cmp m_stage_3 actual &&
+
+		# Compare m to expected contents
+		>empty &&
+		cp -a m_stage_2 expected_final_m &&
+		test_must_fail git merge-file --diff3 \
+			-L "HEAD"                     \
+			-L "merged common ancestors"  \
+			-L "R2^0"                     \
+			expected_final_m              \
+			empty                         \
+			m_stage_3                     &&
+		test_cmp expected_final_m m
+	)
+'
+
 test_done