t4013: make test hash independent

This test produces a large number of diff formats and compares the
output with test files that have content specific to SHA-1. Since we are
more interested in the format of the diffs, and not their specific
values, which are tested elsewhere, add a function which uses sed to
transform these specific object IDs into generic ones of the right size,
which we can then compare.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t4013-diff-various.sh

@@ -120,6 +120,30 @@ test_expect_success setup '
 +*++ [initial] Initial
 EOF
 
+process_diffs () {
+	_x04="[0-9a-f][0-9a-f][0-9a-f][0-9a-f]" &&
+	_x07="$_x05[0-9a-f][0-9a-f]" &&
+	sed -e "s/$OID_REGEX/$ZERO_OID/g" \
+	    -e "s/From $_x40 /From $ZERO_OID /" \
+	    -e "s/from $_x40)/from $ZERO_OID)/" \
+	    -e "s/commit $_x40\$/commit $ZERO_OID/" \
+	    -e "s/commit $_x40 (/commit $ZERO_OID (/" \
+	    -e "s/$_x40 $_x40 $_x40/$ZERO_OID $ZERO_OID $ZERO_OID/" \
+	    -e "s/$_x40 $_x40 /$ZERO_OID $ZERO_OID /" \
+	    -e "s/^$_x40 $_x40$/$ZERO_OID $ZERO_OID/" \
+	    -e "s/^$_x40 /$ZERO_OID /" \
+	    -e "s/^$_x40$/$ZERO_OID/" \
+	    -e "s/$_x07\.\.$_x07/fffffff..fffffff/g" \
+	    -e "s/$_x07,$_x07\.\.$_x07/fffffff,fffffff..fffffff/g" \
+	    -e "s/$_x07 $_x07 $_x07/fffffff fffffff fffffff/g" \
+	    -e "s/$_x07 $_x07 /fffffff fffffff /g" \
+	    -e "s/Merge: $_x07 $_x07/Merge: fffffff fffffff/g" \
+	    -e "s/$_x07\.\.\./fffffff.../g" \
+	    -e "s/ $_x04\.\.\./ ffff.../g" \
+	    -e "s/ $_x04/ ffff/g" \
+	    "$1"
+}
+
 V=$(git version | sed -e 's/^git version //' -e 's/\./\\./g')
 while read magic cmd
 do
@@ -158,13 +182,15 @@ do
 		} >"$actual" &&
 		if test -f "$expect"
 		then
+			process_diffs "$actual" >actual &&
+			process_diffs "$expect" >expect &&
 			case $cmd in
 			*format-patch* | *-stat*)
-				test_i18ncmp "$expect" "$actual";;
+				test_i18ncmp expect actual;;
 			*)
-				test_cmp "$expect" "$actual";;
+				test_cmp expect actual;;
 			esac &&
-			rm -f "$actual"
+			rm -f "$actual" actual expect
 		else
 			# this is to help developing new tests.
 			cp "$actual" "$expect"
@@ -383,16 +409,22 @@ test_expect_success 'log -S requires an argument' '
 test_expect_success 'diff --cached on unborn branch' '
 	echo ref: refs/heads/unborn >.git/HEAD &&
 	git diff --cached >result &&
-	test_cmp "$TEST_DIRECTORY/t4013/diff.diff_--cached" result
+	process_diffs result >actual &&
+	process_diffs "$TEST_DIRECTORY/t4013/diff.diff_--cached" >expected &&
+	test_cmp expected actual
 '
 
 test_expect_success 'diff --cached -- file on unborn branch' '
 	git diff --cached -- file0 >result &&
-	test_cmp "$TEST_DIRECTORY/t4013/diff.diff_--cached_--_file0" result
+	process_diffs result >actual &&
+	process_diffs "$TEST_DIRECTORY/t4013/diff.diff_--cached_--_file0" >expected &&
+	test_cmp expected actual
 '
 test_expect_success 'diff --line-prefix with spaces' '
 	git diff --line-prefix="| | | " --cached -- file0 >result &&
-	test_cmp "$TEST_DIRECTORY/t4013/diff.diff_--line-prefix_--cached_--_file0" result
+	process_diffs result >actual &&
+	process_diffs "$TEST_DIRECTORY/t4013/diff.diff_--line-prefix_--cached_--_file0" >expected &&
+	test_cmp expected actual
 '
 
 test_expect_success 'diff-tree --stdin with log formatting' '