Add tests for `branch --[no-]merged`

Signed-off-by: Lars Hjemli <hjemli@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t3201-branch-contains.sh

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-test_description='branch --contains <commit>'
+test_description='branch --contains <commit>, --merged, and --no-merged'
 
 . ./test-lib.sh
 
@@ -55,4 +55,44 @@ test_expect_success 'branch --contains=side' '
 
 '
 
+test_expect_success 'side: branch --merged' '
+
+	git branch --merged >actual &&
+	{
+		echo "  master" &&
+		echo "* side"
+	} >expect &&
+	test_cmp expect actual
+
+'
+
+test_expect_success 'side: branch --no-merged' '
+
+	git branch --no-merged >actual &&
+	>expect &&
+	test_cmp expect actual
+
+'
+
+test_expect_success 'master: branch --merged' '
+
+	git checkout master &&
+	git branch --merged >actual &&
+	{
+		echo "* master"
+	} >expect &&
+	test_cmp expect actual
+
+'
+
+test_expect_success 'master: branch --no-merged' '
+
+	git branch --no-merged >actual &&
+	{
+		echo "  side"
+	} >expect &&
+	test_cmp expect actual
+
+'
+
 test_done