[PATCH] Add the merge test Linus called "test script from hell".

[Junio C Hamano <junkio@cox.net>]

This is an adaptation to the test framework of a historic test
that was used before three way merge form of read-tree was
introduced, and subsequently used to validate the read-tree -m
merge works correctly.  It covers all the tricky cases known
back then and also have been updated to cover conflicting
files/directories cases since then.

Signed-off-by: Junio C Hamano <junkio@cox.net>
---

t/t0700-read-tree.sh |  313 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 313 insertions(+)
t/t0700-read-tree.sh (. --> 100755)

--- a/t/t0700-read-tree.sh
+++ b/t/t0700-read-tree.sh
@@ -0,0 +1,313 @@
+#!/bin/sh
+#
+# Copyright (c) 2005 Junio C Hamano
+#
+
+test_description='Three way merge with read-tree -m
+
+This test tries three-way merge with read-tree -m
+
+There is one ancestor (called O for Original) and two branches A
+and B derived from it.  We want to do a 3-way merge between A and
+B, using O as the common ancestor.
+
+    merge A O B
+
+Decisions are made by comparing contents of O, A and B pathname
+by pathname.  The result is determined by the following guiding
+principle:
+
+ - If only A does something to it and B does not touch it, take
+   whatever A does.
+
+ - If only B does something to it and A does not touch it, take
+   whatever B does.
+
+ - If both A and B does something but in the same way, take
+   whatever they do.
+
+ - If A and B does something but different things, we need a
+   3-way merge:
+
+   - We cannot do anything about the following cases:
+
+     * O does not have it.  A and B both must be adding to the
+       same path independently.
+
+     * A deletes it.  B must be modifying.
+
+   - Otherwise, A and B are modifying.  Run 3-way merge.
+
+First, the case matrix.
+
+ - Vertical axis is for A'\''s actions.
+ - Horizontal axis is for B'\''s actions.
+
+.----------------------------------------------------------------.
+| A        B | No Action  |   Delete   |   Modify   |    Add     |
+|------------+------------+------------+------------+------------|
+| No Action  |            |            |            |            |
+|            | select O   | delete     | select B   | select B   |
+|            |            |            |            |            |
+|------------+------------+------------+------------+------------|
+| Delete     |            |            | ********** |    can     |
+|            | delete     | delete     | merge      |    not     |
+|            |            |            |            |  happen    |
+|------------+------------+------------+------------+------------|
+| Modify     |            | ********** | ?????????? |    can     |
+|            | select A   | merge      | select A=B |    not     |
+|            |            |            | merge      |  happen    |
+|------------+------------+------------+------------+------------|
+| Add        |            |    can     |    can     | ?????????? |
+|            | select A   |    not     |    not     | select A=B |
+|            |            |  happen    |  happen    | merge      |
+.----------------------------------------------------------------.
+
+In addition:
+
+ SS: a special case of MM, where A and B makes the same modification.
+ LL: a special case of AA, where A and B creates the same file.
+ TT: a special case of MM, where A and B makes mergeable changes.
+ DF: a special case, where A makes a directory and B makes a file.
+
+'
+
+. ./test-lib.sh
+
+# Original tree.
+mkdir Z
+for a in N D M
+do
+    for b in N D M
+    do
+        p=$a$b
+	echo This is $p from the original tree. >$p
+	echo This is Z/$p from the original tree. >Z/$p
+	test_expect_success \
+	    "adding test file $p and Z/$p" \
+	    'git-update-cache --add $p &&
+	    git-update-cache --add Z/$p'
+    done
+done
+echo This is SS from the original tree. >SS
+test_expect_success \
+    'adding test file SS' \
+    'git-update-cache --add SS'
+cat >TT <<\EOF
+This is a trivial merge sample text.
+Branch A is expected to upcase this word, here.
+There are some filler lines to avoid diff context
+conflicts here,
+like this one,
+and this one,
+and this one is yet another one of them.
+At the very end, here comes another line, that is
+the word, expected to be upcased by Branch B.
+This concludes the trivial merge sample file.
+EOF
+test_expect_success \
+    'adding test file TT' \
+    'git-update-cache --add TT'
+test_expect_success \
+    'prepare initial tree' \
+    'tree_O=$(git-write-tree)'
+
+test_expect_success \
+    'commit initial tree' \
+    'commit_O=$(echo "Original tree for the merge test." |
+     git-commit-tree $tree_O)'
+echo $commit_O >.git/HEAD-O
+
+################################################################
+# Branch A and B makes the changes according to the above matrix.
+
+################################################################
+# Branch A
+
+to_remove=$(echo D? Z/D?)
+rm -f $to_remove
+test_expect_success \
+    'change in branch A (removal)' \
+    'git-update-cache --remove $to_remove'
+
+for p in M? Z/M?
+do
+    echo This is modified $p in the branch A. >$p
+    test_expect_success \
+	'change in branch A (modification)' \
+        "git-update-cache $p"
+done
+
+for p in AN AA Z/AN Z/AA
+do
+    echo This is added $p in the branch A. >$p
+    test_expect_success \
+	'change in branch A (addition)' \
+	"git-update-cache --add $p"
+done
+
+echo This is SS from the modified tree. >SS
+echo This is LL from the modified tree. >LL
+test_expect_success \
+    'change in branch A (addition)' \
+    'git-update-cache --add LL &&
+     git-update-cache SS'
+mv TT TT-
+sed -e '/Branch A/s/word/WORD/g' <TT- >TT
+rm -f TT-
+test_expect_success \
+    'change in branch A (edit)' \
+    'git-update-cache TT'
+
+mkdir DF
+echo Branch A makes a file at DF/DF, creating a directory DF. >DF/DF
+test_expect_success \
+    'change in branch A (change file to directory)' \
+    'git-update-cache --add DF/DF'
+
+test_expect_success \
+    'recording branch A tree' \
+    'tree_A=$(git-write-tree)'
+test_expect_success \
+    'committing branch A changes' \
+    'commit_A=$(echo "Branch A for the merge test." |
+           git-commit-tree $tree_A -p $commit_O)'
+echo $commit_A >.git/HEAD-A
+	   
+################################################################
+# Branch B
+# Start from O
+
+rm -rf [NDMASLT][NDMASLT] Z DF
+mkdir Z
+test_expect_success \
+    'reading original tree and checking out' \
+    'git-read-tree $tree_O &&
+     git-checkout-cache -a'
+
+to_remove=$(echo ?D Z/?D)
+rm -f $to_remove
+test_expect_success \
+    'change in branch B (removal)' \
+    "git-update-cache --remove $to_remove"
+
+for p in ?M Z/?M
+do
+    echo This is modified $p in the branch B. >$p
+    test_expect_success \
+	'change in branch B (modification)' \
+	"git-update-cache $p"
+done
+
+for p in NA AA Z/NA Z/AA
+do
+    echo This is added $p in the branch B. >$p
+    test_expect_success \
+	'change in branch B (addition)' \
+	"git-update-cache --add $p"
+done
+echo This is SS from the modified tree. >SS
+echo This is LL from the modified tree. >LL
+test_expect_success \
+    'change in branch B (addition and modification)' \
+    'git-update-cache --add LL &&
+     git-update-cache SS'
+mv TT TT-
+sed -e '/Branch B/s/word/WORD/g' <TT- >TT
+rm -f TT-
+test_expect_success \
+    'change in branch B (modification)' \
+    'git-update-cache TT'
+
+echo Branch B makes a file at DF. >DF
+test_expect_success \
+    'change in branch B (addition of a file to conflict with directory)' \
+    'git-update-cache --add DF'
+
+test_expect_success \
+    'recording branch B tree' \
+    'tree_B=$(git-write-tree)'
+test_expect_success \
+    'committing branch B changes' \
+    'commit_B=$(echo "Branch B for the merge test." |
+           git-commit-tree $tree_B -p $commit_O)'
+echo $commit_B >.git/HEAD-B
+
+################################################################
+# Done preparation.
+
+test_debug '
+    for T in O A B
+    do
+	echo "# $T $(eval git-cat-file commit \$commit_$T | sed -e 1q)"
+    done
+'
+
+################################################################
+# Try merging and showing the various diffs
+
+test_expect_success \
+    '3-way merge with git-read-tree -m' \
+    "git-read-tree -m $tree_O $tree_A $tree_B"
+
+strip_object_id='s/^\([0-7]*\) [0-9a-f]* \([0-3].*\)$/\1 \2/'
+
+test_expect_success \
+    'git-ls-files --stage of the merge result' \
+    'git-ls-files --stage >current- &&
+     sed -e "$strip_object_id" <current- >current'
+
+cat >expected <<\EOF
+100644 2 AA
+100644 3 AA
+100644 2 AN
+100644 1 DD
+100644 3 DF
+100644 2 DF/DF
+100644 1 DM
+100644 3 DM
+100644 1 DN
+100644 3 DN
+100644 2 LL
+100644 3 LL
+100644 1 MD
+100644 2 MD
+100644 1 MM
+100644 2 MM
+100644 3 MM
+100644 0 MN
+100644 3 NA
+100644 1 ND
+100644 2 ND
+100644 0 NM
+100644 0 NN
+100644 0 SS
+100644 1 TT
+100644 2 TT
+100644 3 TT
+100644 2 Z/AA
+100644 3 Z/AA
+100644 2 Z/AN
+100644 1 Z/DD
+100644 1 Z/DM
+100644 3 Z/DM
+100644 1 Z/DN
+100644 3 Z/DN
+100644 1 Z/MD
+100644 2 Z/MD
+100644 1 Z/MM
+100644 2 Z/MM
+100644 3 Z/MM
+100644 0 Z/MN
+100644 3 Z/NA
+100644 1 Z/ND
+100644 2 Z/ND
+100644 0 Z/NM
+100644 0 Z/NN
+EOF
+
+test_expect_success \
+    'validate merge result' \
+    'diff current expected'
+
+test_done
------------------------------------------------