t4024: fix test script to use simpler sed pattern

The earlier test stripped away expected number of 'z' but the output
would have been very hard to read once somebody broke the common tail
optimization.  Instead, count the number of 'z' and show it, to help
diagnosing the problem better in the future.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t4024-diff-optimize-common.sh

@@ -10,58 +10,146 @@ z="$z$z$z$z$z$z$z$z" ;# 512
 z="$z$z$z$z" ;# 2048
 z2047=$(expr "$z" : '.\(.*\)') ; #2047
 
-test_expect_success setup '
+x=zzzzzzzzzz			;# 10
+y="$x$x$x$x$x$x$x$x$x$x"	;# 100
+z="$y$y$y$y$y$y$y$y$y$y"	;# 1000
+z1000=$z
+z100=$y
+z10=$x
 
-	echo "a$z2047" >file-a &&
-	echo "b" >file-b &&
-	echo "$z2047" >>file-b &&
-	echo "c$z2047" | tr -d "\012" >file-c &&
-	echo "d" >file-d &&
-	echo "$z2047" | tr -d "\012" >>file-d &&
+zs() {
+	count="$1"
+	while test "$count" -ge 1000
+	do
+		count=$(($count - 1000))
+		printf "%s" $z1000
+	done
+	while test "$count" -ge 100
+	do
+		count=$(($count - 100))
+		printf "%s" $z100
+	done
+	while test "$count" -ge 10
+	do
+		count=$(($count - 10))
+		printf "%s" $z10
+	done
+	while test "$count" -ge 1
+	do
+		count=$(($count - 1))
+		printf "z"
+	done
+}
 
-	git add file-a file-b file-c file-d &&
+zc () {
+	sed -e "/^index/d" \
+		-e "s/$z1000/Q/g" \
+		-e "s/QQQQQQQQQ/Z9000/g" \
+		-e "s/QQQQQQQQ/Z8000/g" \
+		-e "s/QQQQQQQ/Z7000/g" \
+		-e "s/QQQQQQ/Z6000/g" \
+		-e "s/QQQQQ/Z5000/g" \
+		-e "s/QQQQ/Z4000/g" \
+		-e "s/QQQ/Z3000/g" \
+		-e "s/QQ/Z2000/g" \
+		-e "s/Q/Z1000/g" \
+		-e "s/$z100/Q/g" \
+		-e "s/QQQQQQQQQ/Z900/g" \
+		-e "s/QQQQQQQQ/Z800/g" \
+		-e "s/QQQQQQQ/Z700/g" \
+		-e "s/QQQQQQ/Z600/g" \
+		-e "s/QQQQQ/Z500/g" \
+		-e "s/QQQQ/Z400/g" \
+		-e "s/QQQ/Z300/g" \
+		-e "s/QQ/Z200/g" \
+		-e "s/Q/Z100/g" \
+		-e "s/000Z//g" \
+		-e "s/$z10/Q/g" \
+		-e "s/QQQQQQQQQ/Z90/g" \
+		-e "s/QQQQQQQQ/Z80/g" \
+		-e "s/QQQQQQQ/Z70/g" \
+		-e "s/QQQQQQ/Z60/g" \
+		-e "s/QQQQQ/Z50/g" \
+		-e "s/QQQQ/Z40/g" \
+		-e "s/QQQ/Z30/g" \
+		-e "s/QQ/Z20/g" \
+		-e "s/Q/Z10/g" \
+		-e "s/00Z//g" \
+		-e "s/z/Q/g" \
+		-e "s/QQQQQQQQQ/Z9/g" \
+		-e "s/QQQQQQQQ/Z8/g" \
+		-e "s/QQQQQQQ/Z7/g" \
+		-e "s/QQQQQQ/Z6/g" \
+		-e "s/QQQQQ/Z5/g" \
+		-e "s/QQQQ/Z4/g" \
+		-e "s/QQQ/Z3/g" \
+		-e "s/QQ/Z2/g" \
+		-e "s/Q/Z1/g" \
+		-e "s/0Z//g" \
+	;
+}
 
-	echo "A$z2047" >file-a &&
-	echo "B" >file-b &&
-	echo "$z2047" >>file-b &&
-	echo "C$z2047" | tr -d "\012" >file-c &&
-	echo "D" >file-d &&
-	echo "$z2047" | tr -d "\012" >>file-d
-
-'
-
-cat >expect <<\EOF
-diff --git a/file-a b/file-a
---- a/file-a
-+++ b/file-a
+expect_pattern () {
+	cnt="$1"
+	cat <<EOF
+diff --git a/file-a$cnt b/file-a$cnt
+--- a/file-a$cnt
++++ b/file-a$cnt
 @@ -1 +1 @@
--aZ
-+AZ
-diff --git a/file-b b/file-b
---- a/file-b
-+++ b/file-b
+-Z${cnt}a
++Z${cnt}A
+diff --git a/file-b$cnt b/file-b$cnt
+--- a/file-b$cnt
++++ b/file-b$cnt
 @@ -1 +1 @@
 -b
 +B
-diff --git a/file-c b/file-c
---- a/file-c
-+++ b/file-c
+diff --git a/file-c$cnt b/file-c$cnt
+--- a/file-c$cnt
++++ b/file-c$cnt
 @@ -1 +1 @@
--cZ
+-cZ$cnt
 \ No newline at end of file
-+CZ
++CZ$cnt
 \ No newline at end of file
-diff --git a/file-d b/file-d
---- a/file-d
-+++ b/file-d
+diff --git a/file-d$cnt b/file-d$cnt
+--- a/file-d$cnt
++++ b/file-d$cnt
 @@ -1 +1 @@
 -d
 +D
 EOF
+}
+
+sample='1023 1024 1025 2047 4095'
+
+test_expect_success setup '
+
+	for n in $sample
+	do
+		( zs $n ; echo a ) >file-a$n &&
+		( echo b; zs $n; echo ) >file-b$n &&
+		( printf c; zs $n ) >file-c$n &&
+		( echo d; zs $n ) >file-d$n &&
+
+		git add file-a$n file-b$n file-c$n file-d$n &&
+
+		( zs $n ; echo A ) >file-a$n &&
+		( echo B; zs $n; echo ) >file-b$n &&
+		( printf C; zs $n ) >file-c$n &&
+		( echo D; zs $n ) >file-d$n &&
+
+		expect_pattern $n || break
+
+	done >expect
+'
 
 test_expect_success 'diff -U0' '
 
-	git diff -U0 | sed -e "/^index/d" -e "s/$z2047/Z/g" >actual &&
+	for n in $sample
+	do
+		git diff -U0 file-?$n
+	done | zc >actual &&
 	diff -u expect actual
 
 '