[PATCH] read-tree --emu23.

This new flag causes two-way fast forward to internally use the
three-way merge mechanism.  This behaviour is intended to offer
a better fast forward semantics when used in a dirty work tree.

The new test t1005 is parallel to the existing t1001 "pure
2-way" tests, but some parts that are commented out would fail.
These failures are due to three-way merge enforcing too strict
index requirements for cases that could succeed.  This problem
will be addressed by later patches.

Without even changing three-way mechanism, the --emu23 two-way
fast forward already gives the user an easier-to-handle merge
result when a file that "merged head" updates has local
modifications.  This is demonstrated as "case 16" test in t1005.

Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 316 insertions, 0 deletions

diff --git a/t/t1005-read-tree-m-2way-emu23.sh b/t/t1005-read-tree-m-2way-emu23.sh
new file mode 100644
index 000000000..3345c9dd3
--- /dev/null
+++ b/t/t1005-read-tree-m-2way-emu23.sh
@@ -0,0 +1,316 @@
+#!/bin/sh
+#
+# Copyright (c) 2005 Junio C Hamano
+#
+
+test_description='Two way merge with read-tree --emu23 $H $M
+
+This test tries two-way merge (aka fast forward with carry forward).
+
+There is the head (called H) and another commit (called M), which is
+simply ahead of H.  The index and the work tree contains a state that
+is derived from H, but may also have local changes.  This test checks
+all the combinations described in the two-tree merge "carry forward"
+rules, found in <Documentation/git-rev-tree.txt>.
+
+In the test, these paths are used:
+        bozbar  - in H, stays in M, modified from bozbar to gnusto
+        frotz   - not in H added in M
+        nitfol  - in H, stays in M unmodified
+        rezrov  - in H, deleted in M
+        yomin   - not in H nor M
+'
+. ./test-lib.sh
+
+read_tree_twoway () {
+    git-read-tree --emu23 "$1" "$2" &&
+    git-ls-files --stage &&
+    git-merge-cache git-merge-one-file-script -a &&
+    git-ls-files --stage
+}
+
+_x40='[0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f]'
+_x40="$_x40$_x40$_x40$_x40$_x40$_x40$_x40$_x40"
+compare_change () {
+    	cat current
+	sed -n >current \
+	    -e '/^--- /d; /^+++ /d; /^@@ /d;' \
+	    -e 's/^\([-+][0-7][0-7][0-7][0-7][0-7][0-7]\) '"$_x40"' /\1 X /p' \
+	    "$1"
+	diff -u expected current
+}
+
+check_cache_at () {
+	clean_if_empty=`git-diff-files "$1"`
+	case "$clean_if_empty" in
+	'')  echo "$1: clean" ;;
+	?*)  echo "$1: dirty" ;;
+	esac
+	case "$2,$clean_if_empty" in
+	clean,)		:     ;;
+	clean,?*)	false ;;
+	dirty,)		false ;;
+	dirty,?*)	:     ;;
+	esac
+}
+
+check_stages () {
+    cat >expected_stages
+    git-ls-files --stage | sed -e "s/ $_x40 / X /" >current_stages
+    diff -u expected_stages current_stages
+}
+
+test_expect_success \
+    setup \
+    'echo frotz >frotz &&
+     echo nitfol >nitfol &&
+     echo bozbar >bozbar &&
+     echo rezrov >rezrov &&
+     echo yomin >yomin &&
+     git-update-cache --add nitfol bozbar rezrov &&
+     treeH=`git-write-tree` &&
+     echo treeH $treeH &&
+     git-ls-tree $treeH &&
+
+     echo gnusto >bozbar &&
+     git-update-cache --add frotz bozbar --force-remove rezrov &&
+     git-ls-files --stage >M.out &&
+     treeM=`git-write-tree` &&
+     echo treeM $treeM &&
+     git-ls-tree $treeM &&
+     git-diff-tree $treeH $treeM'
+
+test_expect_success \
+    '1, 2, 3 - no carry forward' \
+    'rm -f .git/index &&
+     read_tree_twoway $treeH $treeM &&
+     git-ls-files --stage >1-3.out &&
+     diff -u M.out 1-3.out &&
+     check_cache_at bozbar dirty &&
+     check_cache_at frotz clean && # different from pure 2-way
+     check_cache_at nitfol dirty'
+
+echo '+100644 X 0	yomin' >expected
+
+test_expect_success \
+    '4 - carry forward local addition.' \
+    'rm -f .git/index &&
+     git-update-cache --add yomin &&
+     read_tree_twoway $treeH $treeM &&
+     git-ls-files --stage >4.out || exit
+     diff -u M.out 4.out >4diff.out
+     compare_change 4diff.out expected &&
+     check_cache_at yomin clean'
+
+# "read-tree -m H I+H M" where !H && !M; so (I+H) not being up-to-date
+# should not matter, but without #3ALT this does not work.
+: test_expect_success \
+    '5 - carry forward local addition.' \
+    'rm -f .git/index &&
+     echo yomin >yomin &&
+     git-update-cache --add yomin &&
+     echo yomin yomin >yomin &&
+     read_tree_twoway $treeH $treeM &&
+     git-ls-files --stage >5.out || exit
+     diff -u M.out 5.out >5diff.out
+     compare_change 5diff.out expected &&
+     check_cache_at yomin dirty'
+
+# "read-tree -m H I+H M" where !H && M && (I+H) == M, so this should
+# succeed (even the entry is clean), but without #5ALT this does not
+# work.
+: test_expect_success \
+    '6 - local addition already has the same.' \
+    'rm -f .git/index &&
+     git-update-cache --add frotz &&
+     read_tree_twoway $treeH $treeM &&
+     git-ls-files --stage >6.out &&
+     diff -u M.out 6.out &&
+     check_cache_at frotz clean'
+
+# Exactly the same pattern as above but with dirty cache.  This also
+# should succeed, but without #5ALT it does not.
+: test_expect_success \
+    '7 - local addition already has the same.' \
+    'rm -f .git/index &&
+     echo frotz >frotz &&
+     git-update-cache --add frotz &&
+     echo frotz frotz >frotz &&
+     read_tree_twoway $treeH $treeM &&
+     git-ls-files --stage >7.out &&
+     diff -u M.out 7.out &&
+     check_cache_at frotz dirty'
+
+test_expect_success \
+    '8 - conflicting addition.' \
+    'rm -f .git/index &&
+     echo frotz frotz >frotz &&
+     git-update-cache --add frotz &&
+     if read_tree_twoway $treeH $treeM; then false; else :; fi'
+
+test_expect_success \
+    '9 - conflicting addition.' \
+    'rm -f .git/index &&
+     echo frotz frotz >frotz &&
+     git-update-cache --add frotz &&
+     echo frotz >frotz &&
+     if read_tree_twoway $treeH $treeM; then false; else :; fi'
+
+test_expect_success \
+    '10 - path removed.' \
+    'rm -f .git/index &&
+     echo rezrov >rezrov &&
+     git-update-cache --add rezrov &&
+     read_tree_twoway $treeH $treeM &&
+     git-ls-files --stage >10.out &&
+     diff -u M.out 10.out'
+
+test_expect_success \
+    '11 - dirty path removed.' \
+    'rm -f .git/index &&
+     echo rezrov >rezrov &&
+     git-update-cache --add rezrov &&
+     echo rezrov rezrov >rezrov &&
+     if read_tree_twoway $treeH $treeM; then false; else :; fi'
+
+test_expect_success \
+    '12 - unmatching local changes being removed.' \
+    'rm -f .git/index &&
+     echo rezrov rezrov >rezrov &&
+     git-update-cache --add rezrov &&
+     if read_tree_twoway $treeH $treeM; then false; else :; fi'
+
+test_expect_success \
+    '13 - unmatching local changes being removed.' \
+    'rm -f .git/index &&
+     echo rezrov rezrov >rezrov &&
+     git-update-cache --add rezrov &&
+     echo rezrov >rezrov &&
+     if read_tree_twoway $treeH $treeM; then false; else :; fi'
+
+cat >expected <<EOF
+-100644 X 0	nitfol
++100644 X 0	nitfol
+EOF
+
+test_expect_success \
+    '14 - unchanged in two heads.' \
+    'rm -f .git/index &&
+     echo nitfol nitfol >nitfol &&
+     git-update-cache --add nitfol &&
+     read_tree_twoway $treeH $treeM &&
+     git-ls-files --stage >14.out || exit
+     diff -u M.out 14.out >14diff.out
+     compare_change 14diff.out expected &&
+     check_cache_at nitfol clean'
+
+test_expect_success \
+    '15 - unchanged in two heads.' \
+    'rm -f .git/index &&
+     echo nitfol nitfol >nitfol &&
+     git-update-cache --add nitfol &&
+     echo nitfol nitfol nitfol >nitfol &&
+     read_tree_twoway $treeH $treeM &&
+     git-ls-files --stage >15.out || exit
+     diff -u M.out 15.out >15diff.out
+     compare_change 15diff.out expected &&
+     check_cache_at nitfol dirty'
+
+# This is different from straight 2-way merge in that it leaves
+# three stages of bozbar in the index file without failing, so
+# the user can run git-diff-stages to examine the situation.
+test_expect_success \
+    '16 - conflicting local change.' \
+    'rm -f .git/index &&
+     echo bozbar bozbar >bozbar &&
+     git-update-cache --add bozbar &&
+     git-read-tree --emu23 $treeH $treeM &&
+     check_stages' <<\EOF
+100644 X 1	bozbar
+100644 X 2	bozbar
+100644 X 3	bozbar
+100644 X 3	frotz
+100644 X 0	nitfol
+100644 X 1	rezrov
+100644 X 2	rezrov
+EOF
+
+test_expect_success \
+    '17 - conflicting local change.' \
+    'rm -f .git/index &&
+     echo bozbar bozbar >bozbar &&
+     git-update-cache --add bozbar &&
+     echo bozbar bozbar bozbar >bozbar &&
+     if read_tree_twoway $treeH $treeM; then false; else :; fi'
+
+test_expect_success \
+    '18 - local change already having a good result.' \
+    'rm -f .git/index &&
+     echo gnusto >bozbar &&
+     git-update-cache --add bozbar &&
+     read_tree_twoway $treeH $treeM &&
+     git-ls-files --stage >18.out &&
+     diff -u M.out 18.out &&
+     check_cache_at bozbar clean'
+
+test_expect_success \
+    '19 - local change already having a good result, further modified.' \
+    'rm -f .git/index &&
+     echo gnusto >bozbar &&
+     git-update-cache --add bozbar &&
+     echo gnusto gnusto >bozbar &&
+     read_tree_twoway $treeH $treeM &&
+     git-ls-files --stage >19.out &&
+     diff -u M.out 19.out &&
+     check_cache_at bozbar dirty'
+
+test_expect_success \
+    '20 - no local change, use new tree.' \
+    'rm -f .git/index &&
+     echo bozbar >bozbar &&
+     git-update-cache --add bozbar &&
+     read_tree_twoway $treeH $treeM &&
+     git-ls-files --stage >20.out &&
+     diff -u M.out 20.out &&
+     check_cache_at bozbar dirty'
+
+test_expect_success \
+    '21 - no local change, dirty cache.' \
+    'rm -f .git/index &&
+     echo bozbar >bozbar &&
+     git-update-cache --add bozbar &&
+     echo gnusto gnusto >bozbar &&
+     if read_tree_twoway $treeH $treeM; then false; else :; fi'
+
+# Also make sure we did not break DF vs DF/DF case.
+test_expect_success \
+    'DF vs DF/DF case setup.' \
+    'rm -f .git/index &&
+     echo DF >DF &&
+     git-update-cache --add DF &&
+     treeDF=`git-write-tree` &&
+     echo treeDF $treeDF &&
+     git-ls-tree $treeDF &&
+
+     rm -f DF &&
+     mkdir DF &&
+     echo DF/DF >DF/DF &&
+     git-update-cache --add --remove DF DF/DF &&
+     treeDFDF=`git-write-tree` &&
+     echo treeDFDF $treeDFDF &&
+     git-ls-tree $treeDFDF &&
+     git-ls-files --stage >DFDF.out'
+
+test_expect_success \
+    'DF vs DF/DF case test.' \
+    'rm -f .git/index &&
+     rm -fr DF &&
+     echo DF >DF &&
+     git-update-cache --add DF &&
+     read_tree_twoway $treeDF $treeDFDF &&
+     git-ls-files --stage >DFDFcheck.out &&
+     diff -u DFDF.out DFDFcheck.out &&
+     check_cache_at DF/DF clean && # different from pure 2-way
+     :'
+
+test_done