chore(tests): add empty test case

Author: duanhongyi

rootfs/api/serializers/__init__.py

@@ -699,6 +699,8 @@ class MetricSerializer(serializers.Serializer):
     stop = serializers.IntegerField(
         min_value=946656000, max_value=4102416000,
         required=False, default=lambda: int(time.time()))
+    step = serializers.IntegerField(
+        min_value=1, max_value=30, required=False, default=14)
     every = serializers.CharField(max_length=50, required=False, default='5m')
 
     def validate(self, attrs):

rootfs/api/tests/test_config.py

@@ -119,6 +119,19 @@ def test_config(self, mock_requests):
         response = self.client.post(url, body)
         self.assertEqual(response.status_code, 201, response.data)
         self.assertEqual([], response.data['values'])
+        # repeat settings
+        value2['value'] = "VALUE2"
+        value3['value'] = None
+        body = {'values': [value2, value3]}
+        response = self.client.post(url, body)
+        self.assertEqual(response.status_code, 201, response.data)
+        self.assertEqual([value2], response.data['values'])
+        # set empty env
+        value1['value'] = ''
+        body = {'values': [value1]}
+        response = self.client.post(url, body)
+        self.assertEqual(response.status_code, 201, response.data)
+        self.assertEqual([value2, value1], response.data['values'])
 
         # disallow put/patch
         response = self.client.put(url)