{[]string{"http://localhost/d1", "http://localhost/d2", "http://localhost/d1", "http://localhost/d4"}, fmt.Errorf("duplicate endpoints found")},
		{[]string{"ftp://server/d1", "http://server/d2", "http://server/d3", "http://server/d4"}, fmt.Errorf("'ftp://server/d1': invalid URL endpoint format")},
		{[]string{"d1", "http://localhost/d2", "d3", "d4"}, fmt.Errorf("mixed style endpoints are not supported")},