Fix issue '<' not supported between instances of 'NoneType' and 'int' (sonic-net#371)

Author: Junchao-Mellanox

sonic_platform_base/sonic_xcvr/api/public/cmis.py

@@ -501,8 +501,12 @@ def get_tx_bias(self):
         if not tx_bias_support:
             return ["N/A" for _ in range(self.NUM_CHANNELS)]
         scale_raw = self.xcvr_eeprom.read(consts.TX_BIAS_SCALE)
+        if scale_raw is None:
+            return ["N/A" for _ in range(self.NUM_CHANNELS)]
         scale = 2**scale_raw if scale_raw < 3 else 1
         tx_bias = self.xcvr_eeprom.read(consts.TX_BIAS_FIELD)
+        if tx_bias is None:
+            return ["N/A" for _ in range(self.NUM_CHANNELS)]
         for key, value in tx_bias.items():
             tx_bias[key] *= scale
         return [tx_bias['LaserBiasTx%dField' % i] for i in range(1, self.NUM_CHANNELS + 1)]
@@ -874,7 +878,7 @@ def get_laser_temperature(self):
                            'high warn': laser_temp_high_warn,
                            'low warn': laser_temp_low_warn}
         return laser_temp_dict
-    
+
     def _get_laser_temp_threshold(self, field):
         LASER_TEMP_SCALE = 256.0
         value = self.xcvr_eeprom.read(field)

tests/sonic_xcvr/test_cmis.py

@@ -377,6 +377,16 @@ def test_get_tx_bias(self, mock_response, expected):
         result = self.api.get_tx_bias()
         assert result == expected
 
+    def test_get_tx_bias_neg(self):
+        self.api.get_tx_bias_support = MagicMock(return_value=True)
+        self.api.xcvr_eeprom.read = MagicMock()
+        # scale_raw is None, verify no crash
+        self.api.xcvr_eeprom.read.return_value = None
+        self.api.get_tx_bias()
+        # scale_raw is 1, tx_bias is None, verify no crash
+        self.api.xcvr_eeprom.read.side_effect = [1, None]
+        self.api.get_tx_bias()
+
     @pytest.mark.parametrize("mock_response, expected", [
         ([False, True], True)
     ])