replace_object: add a test case

In this patch the setup code is very big, but this will be used in
test cases that will be added later.
Signed-off-by: NChristian Couder <chriscool@tuxfamily.org>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

t/t6050-replace.sh

+#!/bin/sh
+#
+# Copyright (c) 2008 Christian Couder
+#
+test_description='Tests replace refs functionality'
+
+exec </dev/null
+
+. ./test-lib.sh
+
+add_and_commit_file()
+{
+    _file="$1"
+    _msg="$2"
+
+    git add $_file || return $?
+    test_tick || return $?
+    git commit --quiet -m "$_file: $_msg"
+}
+
+HASH1=
+HASH2=
+HASH3=
+HASH4=
+HASH5=
+HASH6=
+HASH7=
+
+test_expect_success 'set up buggy branch' '
+     echo "line 1" >> hello &&
+     echo "line 2" >> hello &&
+     echo "line 3" >> hello &&
+     echo "line 4" >> hello &&
+     add_and_commit_file hello "4 lines" &&
+     HASH1=$(git rev-parse --verify HEAD) &&
+     echo "line BUG" >> hello &&
+     echo "line 6" >> hello &&
+     echo "line 7" >> hello &&
+     echo "line 8" >> hello &&
+     add_and_commit_file hello "4 more lines with a BUG" &&
+     HASH2=$(git rev-parse --verify HEAD) &&
+     echo "line 9" >> hello &&
+     echo "line 10" >> hello &&
+     add_and_commit_file hello "2 more lines" &&
+     HASH3=$(git rev-parse --verify HEAD) &&
+     echo "line 11" >> hello &&
+     add_and_commit_file hello "1 more line" &&
+     HASH4=$(git rev-parse --verify HEAD) &&
+     sed -e "s/BUG/5/" hello > hello.new &&
+     mv hello.new hello &&
+     add_and_commit_file hello "BUG fixed" &&
+     HASH5=$(git rev-parse --verify HEAD) &&
+     echo "line 12" >> hello &&
+     echo "line 13" >> hello &&
+     add_and_commit_file hello "2 more lines" &&
+     HASH6=$(git rev-parse --verify HEAD)
+     echo "line 14" >> hello &&
+     echo "line 15" >> hello &&
+     echo "line 16" >> hello &&
+     add_and_commit_file hello "again 3 more lines" &&
+     HASH7=$(git rev-parse --verify HEAD)
+'
+
+test_expect_success 'replace the author' '
+     git cat-file commit $HASH2 | grep "author A U Thor" &&
+     R=$(git cat-file commit $HASH2 | sed -e "s/A U/O/" | git hash-object -t commit --stdin -w) &&
+     git cat-file commit $R | grep "author O Thor" &&
+     git update-ref refs/replace/$HASH2 $R &&
+     git show HEAD~5 | grep "O Thor" &&
+     git show $HASH2 | grep "O Thor"
+'
+
+#
+#
+test_done