Fix incorrect output for 'fuel2 node list'

Change-Id: Ic5ca3882c54a4dccda0d5b318174555a5fb891ab
Closes-Bug: #1471852

fuelclient/common/data_utils.py

@@ -37,6 +37,9 @@ def get_display_data_single(fields, data):
         if not val and val not in (0, None, False, ''):
             val = '-'
 
+        if isinstance(val, list):
+            val = ', '.join(str(item) for item in val)
+
         result.append(val)
 
     return result

fuelclient/tests/common/unit/test_utils.py

@@ -199,6 +199,13 @@ class TestUtils(base.UnitTestCase):
         result = data_utils.get_display_data_single(fields, test_data)
         self.assertEqual([1, '-', '-'], result)
 
+    def test_get_display_data_single_list_val(self):
+        test_data = {'a': 1, 'b': ['2'], 'c': ['3', '4']}
+        fields = ('a', 'b', 'c')
+
+        result = data_utils.get_display_data_single(fields, test_data)
+        self.assertEqual([1, '2', '3, 4'], result)
+
     def test_get_display_data_bad_key(self):
         test_data = {'a': 1, 'b': 2, 'c': 3}
         fields = ('b', 'bad_key')