t5520: test for failure if index has unresolved entries

Commit d38a30d (Be more user-friendly when refusing to do something
because of conflict., 2010-01-12) introduced code paths to git-pull
which will error out with user-friendly advices if the user is in the
middle of a merge or has unmerged files.

Implement tests to ensure that git-pull will not run, and will print
these advices, if the user is in the middle of a merge or has unmerged
files in the index.

Signed-off-by: Paul Tan <pyokagan@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: pyokagan

t/t5520-pull.sh

@@ -164,6 +164,25 @@ test_expect_success 'fail if upstream branch does not exist' '
 	test "$(cat file)" = file
 '
 
+test_expect_success 'fail if the index has unresolved entries' '
+	git checkout -b third second^ &&
+	test_when_finished "git checkout -f copy && git branch -D third" &&
+	test "$(cat file)" = file &&
+	test_commit modified2 file &&
+	test -z "$(git ls-files -u)" &&
+	test_must_fail git pull . second &&
+	test -n "$(git ls-files -u)" &&
+	cp file expected &&
+	test_must_fail git pull . second 2>err &&
+	test_i18ngrep "Pull is not possible because you have unmerged files" err &&
+	test_cmp expected file &&
+	git add file &&
+	test -z "$(git ls-files -u)" &&
+	test_must_fail git pull . second 2>err &&
+	test_i18ngrep "You have not concluded your merge" err &&
+	test_cmp expected file
+'
+
 test_expect_success '--rebase' '
 	git branch to-rebase &&
 	echo modified again > file &&