t3422: new testcases for checking when incompatible options passed

git rebase is split into three types: am, merge, and interactive.  Various
options imply different types, and which mode we are using determine which
sub-script (git-rebase--$type) is executed to finish the work.  Not all
options work with all types, so add tests for combinations where we expect
to receive an error rather than having options be silently ignored.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t3422-rebase-incompatible-options.sh

@@ -0,0 +1,88 @@
+#!/bin/sh
+
+test_description='test if rebase detects and aborts on incompatible options'
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	test_seq 2 9 >foo &&
+	git add foo &&
+	git commit -m orig &&
+
+	git branch A &&
+	git branch B &&
+
+	git checkout A &&
+	test_seq 1 9 >foo &&
+	git add foo &&
+	git commit -m A &&
+
+	git checkout B &&
+	echo "q qfoo();" | q_to_tab >>foo &&
+	git add foo &&
+	git commit -m B
+'
+
+#
+# Rebase has lots of useful options like --whitepsace=fix, which are
+# actually all built in terms of flags to git-am.  Since neither
+# --merge nor --interactive (nor any options that imply those two) use
+# git-am, using them together will result in flags like --whitespace=fix
+# being ignored.  Make sure rebase warns the user and aborts instead.
+#
+
+test_rebase_am_only () {
+	opt=$1
+	shift
+	test_expect_failure "$opt incompatible with --merge" "
+		git checkout B^0 &&
+		test_must_fail git rebase $opt --merge A
+	"
+
+	test_expect_failure "$opt incompatible with --strategy=ours" "
+		git checkout B^0 &&
+		test_must_fail git rebase $opt --strategy=ours A
+	"
+
+	test_expect_failure "$opt incompatible with --strategy-option=ours" "
+		git checkout B^0 &&
+		test_must_fail git rebase $opt --strategy-option=ours A
+	"
+
+	test_expect_failure "$opt incompatible with --interactive" "
+		git checkout B^0 &&
+		test_must_fail git rebase $opt --interactive A
+	"
+
+	test_expect_failure "$opt incompatible with --exec" "
+		git checkout B^0 &&
+		test_must_fail git rebase $opt --exec 'true' A
+	"
+
+}
+
+test_rebase_am_only --whitespace=fix
+test_rebase_am_only --ignore-whitespace
+test_rebase_am_only --committer-date-is-author-date
+test_rebase_am_only -C4
+
+test_expect_success '--preserve-merges incompatible with --signoff' '
+	git checkout B^0 &&
+	test_must_fail git rebase --preserve-merges --signoff A
+'
+
+test_expect_failure '--preserve-merges incompatible with --rebase-merges' '
+	git checkout B^0 &&
+	test_must_fail git rebase --preserve-merges --rebase-merges A
+'
+
+test_expect_failure '--rebase-merges incompatible with --strategy' '
+	git checkout B^0 &&
+	test_must_fail git rebase --rebase-merges -s resolve A
+'
+
+test_expect_failure '--rebase-merges incompatible with --strategy-option' '
+	git checkout B^0 &&
+	test_must_fail git rebase --rebase-merges -Xignore-space-change A
+'
+
+test_done