Raise error if error flag is not an accepted value

docs/contracts.rst

@@ -742,14 +742,14 @@ For example:
 
    .. code-block:: python
 
-       >>> from web3._utils.events import EventLogErrorFlags
+       >>> from web3._utils.events import STRICT, IGNORE, DISCARD, WARN
 
        >>> tx_hash = contract.functions.myFunction(12345).transact({'to':contract_address})
        >>> tx_receipt = w3.eth.getTransactionReceipt(tx_hash)
-       >>> returned_logs = contract.events.myEvent().processReceipt(tx_receipt, errors=EventLogErrorFlags.ignore)
+       >>> returned_logs = contract.events.myEvent().processReceipt(tx_receipt, errors=IGNORE)
        >>> assert returned_logs[0] == tx_receipt['logs'][0]
        True
-       >>> returned_logs = contract.events.myEvent().processReceipt(tx_receipt, errors=EventLogErrorFlags.discard)
+       >>> returned_logs = contract.events.myEvent().processReceipt(tx_receipt, errors=DISCARD)
        >>> assert returned_logs == ()
        True
 

tests/core/contracts/test_extracting_event_data.py

@@ -5,9 +5,11 @@
 )
 
 from web3._utils.events import (
+    EventLogErrorFlags,
     DISCARD,
     IGNORE,
     STRICT,
+    WARN,
     get_event_data,
 )
 
@@ -271,46 +273,21 @@ def test_event_rich_log(
 
 
 @pytest.mark.parametrize(
-    'errors',
+    'error_flag',
     (
+        (DISCARD),
+        (IGNORE),
         (STRICT),
-        (),
-    )
-)
-def test_event_processing_with_strict_error_flag(
-        web3,
-        event_contract,
-        indexed_event_contract,
-        wait_for_transaction,
-        errors):
-
-    txn_hash = indexed_event_contract.functions.logTwoEvents(12345).transact()
-    wait_for_transaction(web3, txn_hash)
-
-    event_instance = indexed_event_contract.events.LogSingleWithIndex()
-
-    event_contract_fn = event_contract.functions.logTwoEvents
-    dup_txn_hash = event_contract_fn(12345).transact()
-    dup_txn_receipt = wait_for_transaction(web3, dup_txn_hash)
-
-    with pytest.raises(ValueError, match="Expected 1 log topics.  Got 0"):
-        event_instance.processReceipt(dup_txn_receipt, errors=errors)
-
-
-@pytest.mark.parametrize(
-    'errors,rich_log_length',
-    (
-        (DISCARD, 0),
-        (IGNORE, 1),
+        (WARN),
+        ('something_else'),
     )
 )
 def test_event_processing_with_caught_errors(
         web3,
         event_contract,
         indexed_event_contract,
         wait_for_transaction,
-        errors,
-        rich_log_length):
+        error_flag):
 
     emitter_fn = indexed_event_contract.functions.logTwoEvents
 
@@ -323,18 +300,27 @@ def test_event_processing_with_caught_errors(
 
     event_instance = indexed_event_contract.events.LogSingleWithIndex()
 
-    returned_logs = event_instance.processReceipt(dup_txn_receipt, errors=errors)
-
-    assert len(returned_logs) == rich_log_length
-
-    if len(returned_logs) == 0:
+    if error_flag is DISCARD:
+        returned_logs = event_instance.processReceipt(dup_txn_receipt, errors=error_flag)
         assert returned_logs == ()
-    elif len(returned_logs) == 1:
+    elif error_flag is IGNORE:
+        returned_logs = event_instance.processReceipt(dup_txn_receipt, errors=error_flag)
+        assert len(returned_logs) == 1
         returned_log = dict(returned_logs[0])
 
         assert repr(returned_log['errors']) == "ValueError('Expected 1 log topics.  Got 0')"
         del returned_log['errors']
         assert returned_log == dup_txn_receipt['logs'][0]
         assert is_same_address(returned_log['address'], event_contract.address)
+    elif error_flag is WARN:
+        with pytest.warns(UserWarning, match="Expected 1 log topics.  Got 0"):
+            returned_log = event_instance.processReceipt(dup_txn_receipt, errors=error_flag)
+            assert len(returned_log) == 0
+    elif error_flag is STRICT:
+        with pytest.raises(ValueError, match="Expected 1 log topics.  Got 0"):
+            event_instance.processReceipt(dup_txn_receipt, errors=error_flag)
+    elif error_flag is 'something_else':
+        with pytest.raises(AttributeError, match="Error flag must be one of:"):
+            returned_log = event_instance.processReceipt(dup_txn_receipt, errors=error_flag)
     else:
         raise Exception('Unreachable!')

web3/_utils/events.py

@@ -450,11 +450,13 @@ def _encode(self, value):
 
 
 class EventLogErrorFlags(Enum):
-    STRICT = 'strict'
-    IGNORE = 'ignore'
-    DISCARD = 'discard'
+    Discard = 'discard'
+    Ignore = 'ignore'
+    Strict = 'strict'
+    Warn = 'warn'
 
 
-STRICT = EventLogErrorFlags.STRICT
-IGNORE = EventLogErrorFlags.IGNORE
-DISCARD = EventLogErrorFlags.DISCARD
+DISCARD = EventLogErrorFlags.Discard
+IGNORE = EventLogErrorFlags.Ignore
+STRICT = EventLogErrorFlags.Strict
+WARN = EventLogErrorFlags.Warn

web3/contract.py

@@ -3,6 +3,7 @@
 """
 import copy
 import itertools
+import warnings
 
 from eth_abi import (
     decode_abi,
@@ -65,6 +66,8 @@
     DISCARD,
     IGNORE,
     STRICT,
+    WARN,
+    EventLogErrorFlags,
     EventFilterBuilder,
     get_event_data,
     is_dynamic_sized_type,
@@ -991,8 +994,17 @@ def _get_event_abi(cls):
 
     @combomethod
     def processReceipt(self, txn_receipt, errors=STRICT):
+        self.check_for_valid_error_flag(errors)
         return self._parse_logs(txn_receipt, errors)
 
+    def check_for_valid_error_flag(self, errors):
+        keys = [key.upper() for key in EventLogErrorFlags.__members__.keys()]
+        try:
+            errors.name
+        except AttributeError:
+            raise AttributeError(f'Error flag must be one of: {keys}')
+
+
     @to_tuple
     def _parse_logs(self, txn_receipt, errors):
         for log in txn_receipt['logs']:
@@ -1007,6 +1019,13 @@ def _parse_logs(self, txn_receipt, errors):
                     new_log = MutableAttributeDict(log)
                     new_log["errors"] = e
                     rich_log = AttributeDict(new_log)
+                elif errors == WARN:
+                    warnings.warn(
+                        f"The log with transaction hash: {log.transactionHash} and \
+                        logIndex: {log.logIndex} encountered the following \
+                        error during processing: {e}. It has been discarded"
+                    )
+                    continue
                 else:
                     raise e
             yield rich_log