[PATCH] read-tree: save more user hassles during fast-forward.

This implements the "never lose the current cache information or
the work tree state, but favor a successful merge over merge
failure" principle in the fast-forward two-tree merge operation.

It comes with a set of tests to cover all the cases described in
the case matrix found in the new documentation.

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

1 files changed, 281 insertions, 0 deletions

diff --git a/t/t1001-read-tree-m-2way.sh b/t/t1001-read-tree-m-2way.sh
new file mode 100755
index 0000000000..33041f3cce
--- /dev/null
+++ b/t/t1001-read-tree-m-2way.sh
@@ -0,0 +1,281 @@
+#!/bin/sh
+#
+# Copyright (c) 2005 Junio C Hamano
+#
+
+test_description='Two way merge with read-tree -m $H $M
+
+This test tries two-way merge (aka fast forward with carry forward).
+
+There is the head (called H) and another commit (called M), which is
+simply ahead of H.  The index and the work tree contains a state that
+is derived from H, but may also have local changes.  This test checks
+all the combinations described in the two-tree merge "carry forward"
+rules, found in <Documentation/git-rev-tree.txt>.
+
+In the test, these paths are used:
+        bozbar  - in H, stays in M, modified from bozbar to gnusto
+        frotz   - not in H added in M
+        nitfol  - in H, stays in M unmodified
+        rezrov  - in H, deleted in M
+        yomin   - not in H nor M
+'
+. ./test-lib.sh
+
+_x40='[0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f]'
+_x40="$_x40$_x40$_x40$_x40$_x40$_x40$_x40$_x40"
+compare_change () {
+	sed >current \
+	    -e '/^--- /d; /^+++ /d; /^@@ /d;' \
+	    -e 's/^\(.[0-7][0-7][0-7][0-7][0-7][0-7]\) '"$_x40"' /\1 X /' "$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
+}
+
+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 &&
+     git-read-tree -m $treeH $treeM &&
+     git-ls-files --stage >1-3.out &&
+     cmp M.out 1-3.out &&
+     check_cache_at bozbar dirty &&
+     check_cache_at frotz dirty &&
+     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 &&
+     git-read-tree -m $treeH $treeM &&
+     git-ls-files --stage >4.out || exit
+     diff --unified=0 M.out 4.out >4diff.out
+     compare_change 4diff.out expected &&
+     check_cache_at yomin clean'
+
+test_expect_success \
+    '5 - carry forward local addition.' \
+    'rm -f .git/index &&
+     echo yomin >yomin &&
+     git-update-cache --add yomin &&
+     echo yomin yomin >yomin &&
+     git-read-tree -m $treeH $treeM &&
+     git-ls-files --stage >5.out || exit
+     diff --unified=0 M.out 5.out >5diff.out
+     compare_change 5diff.out expected &&
+     check_cache_at yomin dirty'
+
+test_expect_success \
+    '6 - local addition already has the same.' \
+    'rm -f .git/index &&
+     git-update-cache --add frotz &&
+     git-read-tree -m $treeH $treeM &&
+     git-ls-files --stage >6.out &&
+     diff --unified=0 M.out 6.out &&
+     check_cache_at frotz clean'
+
+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 &&
+     git-read-tree -m $treeH $treeM &&
+     git-ls-files --stage >7.out &&
+     diff --unified=0 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 git-read-tree -m $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 git-read-tree -m $treeH $treeM; then false; else :; fi'
+
+test_expect_success \
+    '10 - path removed.' \
+    'rm -f .git/index &&
+     echo rezrov >rezrov &&
+     git-update-cache --add rezrov &&
+     git-read-tree -m $treeH $treeM &&
+     git-ls-files --stage >10.out &&
+     cmp 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 git-read-tree -m $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 git-read-tree -m $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 git-read-tree -m $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 &&
+     git-read-tree -m $treeH $treeM &&
+     git-ls-files --stage >14.out || exit
+     diff --unified=0 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 &&
+     git-read-tree -m $treeH $treeM &&
+     git-ls-files --stage >15.out || exit
+     diff --unified=0 M.out 15.out >15diff.out
+     compare_change 15diff.out expected &&
+     check_cache_at nitfol dirty'
+
+test_expect_success \
+    '16 - conflicting local change.' \
+    'rm -f .git/index &&
+     echo bozbar bozbar >bozbar &&
+     git-update-cache --add bozbar &&
+     if git-read-tree -m $treeH $treeM; then false; else :; fi'
+
+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 git-read-tree -m $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 &&
+     git-read-tree -m $treeH $treeM &&
+     git-ls-files --stage >18.out &&
+     diff --unified=0 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 &&
+     git-read-tree -m $treeH $treeM &&
+     git-ls-files --stage >19.out &&
+     diff --unified=0 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 &&
+     git-read-tree -m $treeH $treeM &&
+     git-ls-files --stage >20.out &&
+     diff --unified=0 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 git-read-tree -m $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 &&
+     git-read-tree -m $treeDF $treeDFDF &&
+     git-ls-files --stage >DFDFcheck.out &&
+     diff --unified=0 DFDF.out DFDFcheck.out &&
+     check_cache_at DF/DF dirty'
+
+test_done