Handle "not supported" errors in the core Transaction function.

If the Notecard's response contains an error with "{not-supported}", do not
retry the transaction.

Author: haydenroche5

notecard/notecard.py

@@ -41,19 +41,22 @@
 use_periphery = False
 use_serial_lock = False
 
-if sys.implementation.name == 'cpython' and (sys.platform == 'linux' or sys.platform == 'linux2'):
+if sys.implementation.name == 'cpython' and (sys.platform == 'linux'
+                                             or sys.platform == 'linux2'):
     use_periphery = True
     from periphery import I2C
 
     use_serial_lock = True
     from filelock import FileLock
     from filelock import Timeout as SerialLockTimeout
 else:
+
     class SerialLockTimeout(Exception):
         """A null SerialLockTimeout for when use_serial_lock is False."""
 
         pass
 
+
 use_i2c_lock = not use_periphery and sys.implementation.name != 'micropython'
 
 NOTECARD_I2C_ADDRESS = 0x17
@@ -310,9 +313,9 @@ def Transaction(self, req, lock=True):
             if rsp_expected:
                 while retries_left > 0:
                     try:
-                        rsp_bytes = self._transact(
-                            req_bytes, rsp_expected=True,
-                            timeout_secs=timeout_secs)
+                        rsp_bytes = self._transact(req_bytes,
+                                                   rsp_expected=True,
+                                                   timeout_secs=timeout_secs)
                     except Exception as e:
                         if self._debug:
                             print(e)
@@ -344,7 +347,7 @@ def Transaction(self, req, lock=True):
                         continue
 
                     if 'err' in rsp_json:
-                        if '{io}' in rsp_json['err']:
+                        if '{io}' in rsp_json['err'] and '{not-supported}' not in rsp_json['err']:
                             if self._debug:
                                 print('Response has error field indicating ' + \
                                       f'I/O error: {rsp_json}')
@@ -366,7 +369,8 @@ def Transaction(self, req, lock=True):
                     break
             else:
                 try:
-                    self._transact(req_bytes, rsp_expected=False,
+                    self._transact(req_bytes,
+                                   rsp_expected=False,
                                    timeout_secs=timeout_secs)
                 except Exception as e:
                     error = True
@@ -423,7 +427,9 @@ def SetTransactionPins(self, rtx_pin, ctx_pin):
 class OpenSerial(Notecard):
     """Notecard class for Serial communication."""
 
-    def _transact(self, req_bytes, rsp_expected,
+    def _transact(self,
+                  req_bytes,
+                  rsp_expected,
                   timeout_secs=CARD_INTER_TRANSACTION_TIMEOUT_SEC):
         self.transmit(req_bytes)
 
@@ -441,7 +447,8 @@ def _transact(self, req_bytes, rsp_expected,
 
         return self.receive()
 
-    def receive(self, timeout_secs=CARD_INTRA_TRANSACTION_TIMEOUT_SEC,
+    def receive(self,
+                timeout_secs=CARD_INTRA_TRANSACTION_TIMEOUT_SEC,
                 delay=True):
         """Read a newline-terminated batch of data from the Notecard."""
         data = bytearray()
@@ -638,7 +645,8 @@ def _write(self, data):
         """Perform a serial-over-I2C write."""
         self._platform_write(bytearray([len(data)]), data)
 
-    def receive(self, timeout_secs=CARD_INTRA_TRANSACTION_TIMEOUT_SEC,
+    def receive(self,
+                timeout_secs=CARD_INTRA_TRANSACTION_TIMEOUT_SEC,
                 delay=True):
         """Read a newline-terminated batch of data from the Notecard."""
         read_len = 0
@@ -709,7 +717,9 @@ def transmit(self, data, delay=True):
             if delay:
                 time.sleep(CARD_REQUEST_I2C_CHUNK_DELAY_MS / 1000)
 
-    def _transact(self, req_bytes, rsp_expected,
+    def _transact(self,
+                  req_bytes,
+                  rsp_expected,
                   timeout_secs=CARD_INTER_TRANSACTION_TIMEOUT_SEC):
         self.transmit(req_bytes)
 

test/test_notecard.py

@@ -294,6 +294,16 @@ def test_transaction_retries_on_io_error_in_response(
             assert card._transact.call_count == \
                    notecard.CARD_TRANSACTION_RETRIES
 
+    def test_transaction_does_not_retry_on_not_supported_error_in_response(
+            self, arrange_transaction_test):
+        card = arrange_transaction_test()
+        req = {"req": "hub.status"}
+
+        with patch('notecard.notecard.json.loads',
+                   return_value={'err': 'some error {io} {not-supported}'}):
+            card.Transaction(req)
+            assert card._transact.call_count == 1
+
     def test_transaction_does_not_retry_on_bad_bin_error_in_response(
             self, arrange_transaction_test):
         card = arrange_transaction_test()