t6031: generalize for recursive and resolve strategies

This script tests the filemode handling of merge-recursive,
but we do not test the same thing for merge-resolve. Let's
generalize the script a little:

  1. Break out the setup steps for each test into a separate
     snippet.

  2. For each test, run it twice; once with "-s recursive"
     and once with "-s resolve". We can avoid repeating
     ourselves by adding a function.

  3. Since we have a nice abstracted function, we can make
     our tests more thorough by testing both directions
     (change on "ours" versus "theirs").

This improves our test coverage, and will make this the
place to add more tests related to merging mode changes.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t6031-merge-filemode.sh

@@ -0,0 +1,77 @@
+#!/bin/sh
+
+test_description='merge: handle file mode'
+. ./test-lib.sh
+
+test_expect_success 'set up mode change in one branch' '
+	: >file1 &&
+	git add file1 &&
+	git commit -m initial &&
+	git checkout -b a1 master &&
+	: >dummy &&
+	git add dummy &&
+	git commit -m a &&
+	git checkout -b b1 master &&
+	test_chmod +x file1 &&
+	git add file1 &&
+	git commit -m b1
+'
+
+do_one_mode () {
+	strategy=$1
+	us=$2
+	them=$3
+	test_expect_success "resolve single mode change ($strategy, $us)" '
+		git checkout -f $us &&
+		git merge -s $strategy $them &&
+		git ls-files -s file1 | grep ^100755
+	'
+
+	test_expect_success FILEMODE "verify executable bit on file ($strategy, $us)" '
+		test -x file1
+	'
+}
+
+do_one_mode recursive a1 b1
+do_one_mode recursive b1 a1
+do_one_mode resolve a1 b1
+do_one_mode resolve b1 a1
+
+test_expect_success 'set up mode change in both branches' '
+	git reset --hard HEAD &&
+	git checkout -b a2 master &&
+	: >file2 &&
+	H=$(git hash-object file2) &&
+	test_chmod +x file2 &&
+	git commit -m a2 &&
+	git checkout -b b2 master &&
+	: >file2 &&
+	git add file2 &&
+	git commit -m b2 &&
+	{
+		echo "100755 $H 2	file2"
+		echo "100644 $H 3	file2"
+	} >expect
+'
+
+do_both_modes () {
+	strategy=$1
+	test_expect_success "detect conflict on double mode change ($strategy)" '
+		git reset --hard &&
+		git checkout -f a2 &&
+		test_must_fail git merge -s $strategy b2 &&
+		git ls-files -u >actual &&
+		test_cmp actual expect &&
+		git ls-files -s file2 | grep ^100755
+	'
+
+	test_expect_success FILEMODE "verify executable bit on file ($strategy)" '
+		test -x file2
+	'
+}
+
+# both sides are equivalent, so no need to run both ways
+do_both_modes recursive
+do_both_modes resolve
+
+test_done