Add hasattr to ContractFunction and ContractCaller

Author: kclowes

tests/core/contracts/test_contract_attributes.py

@@ -0,0 +1,48 @@
+import pytest
+
+from web3.exceptions import (
+    ABIEventFunctionNotFound,
+    ABIFunctionNotFound,
+)
+
+
+@pytest.fixture()
+def abi():
+    return '''[{"anonymous":false,"inputs":[{"indexed":false,"name":"value","type":"uint256"}],"name":"Increased","type":"function"}, {"anonymous":false,"inputs":[{"indexed":false,"name":"value","type":"uint256"}],"name":"Increased","type":"event"}]'''  # noqa: E501
+
+
+@pytest.mark.parametrize(
+    'attribute',
+    ('functions', 'events', 'caller')
+)
+def test_getattr(web3, abi, attribute):
+    contract = web3.eth.contract(abi=abi)
+    contract_attribute = getattr(contract, attribute)
+    assert getattr(contract_attribute, "Increased")
+
+
+@pytest.mark.parametrize(
+    'attribute,error', (
+        ('functions', ABIFunctionNotFound),
+        ('events', ABIEventFunctionNotFound),
+        ('caller', ABIFunctionNotFound),
+    )
+)
+def test_getattr_raises_error(web3, abi, attribute, error):
+    contract = web3.eth.contract(abi=abi)
+    contract_attribute = getattr(contract, attribute)
+
+    with pytest.raises(error):
+        getattr(contract_attribute, "Decreased")
+
+
+@pytest.mark.parametrize(
+    'attribute',
+    ('functions', 'events', 'caller')
+)
+def test_hasattr(web3, abi, attribute):
+    contract = web3.eth.contract(abi=abi)
+    contract_attribute = getattr(contract, attribute)
+
+    assert hasattr(contract_attribute, "Increased") is True
+    assert hasattr(contract_attribute, "Decreased") is False

tests/core/contracts/test_contract_call_interface.py

@@ -23,6 +23,7 @@
     contract_ens_addresses,
 )
 from web3.exceptions import (
+    ABIFunctionNotFound,
     BadFunctionCallOutput,
     BlockNumberOutofRange,
     InvalidAddress,

tests/core/contracts/test_extracting_event_data.py

@@ -12,7 +12,6 @@
     get_event_data,
 )
 from web3.exceptions import (
-    ABIEventFunctionNotFound,
     LogTopicError,
     ValidationError,
 )
@@ -114,29 +113,6 @@ def dup_txn_receipt(
     return wait_for_transaction(web3, dup_txn_hash)
 
 
-@pytest.fixture()
-def single_event_abi():
-    return '''[{"anonymous":false,"inputs":[{"indexed":false,"name":"value","type":"uint256"}],"name":"Increased","type":"event"}]'''  # noqa: E501
-
-
-def test_contract_event_getattr(web3, single_event_abi):
-    contract = web3.eth.contract(abi=single_event_abi)
-    assert getattr(contract.events, "Increased")
-
-
-def test_contract_event_getattr_raises_error(web3, single_event_abi):
-    contract = web3.eth.contract(abi=single_event_abi)
-
-    with pytest.raises(ABIEventFunctionNotFound):
-        getattr(contract.events, "Decreased")
-
-
-def test_contract_event_hasattr(web3, single_event_abi):
-    contract = web3.eth.contract(abi=single_event_abi)
-    assert hasattr(contract.events, "Increased") is True
-    assert hasattr(contract.events, "Decreased") is False
-
-
 @pytest.mark.parametrize(
     'contract_fn,event_name,call_args,expected_args',
     (

web3/contract.py

@@ -111,6 +111,7 @@
 )
 from web3.exceptions import (
     ABIEventFunctionNotFound,
+    ABIFunctionNotFound,
     BadFunctionCallOutput,
     BlockNumberOutofRange,
     FallbackNotFound,
@@ -186,7 +187,7 @@ def __getattr__(self, function_name: str) -> "ContractFunction":
                 "Are you sure you provided the correct contract abi?"
             )
         elif function_name not in self.__dict__['_functions']:
-            raise MismatchedABI(
+            raise ABIFunctionNotFound(
                 "The function '{}' was not found in this contract's abi. ".format(function_name),
                 "Are you sure you provided the correct contract abi?"
             )
@@ -196,6 +197,12 @@ def __getattr__(self, function_name: str) -> "ContractFunction":
     def __getitem__(self, function_name: str) -> ABIFunction:
         return getattr(self, function_name)
 
+    def __hasattr__(self, event_name: str) -> bool:
+        try:
+            return event_name in self.__dict__['_events']
+        except ABIFunctionNotFound:
+            return False
+
 
 class ContractEvents:
     """Class containing contract event objects
@@ -1360,7 +1367,7 @@ def __getattr__(self, function_name: str) -> Any:
             )
         elif function_name not in set(fn['name'] for fn in self._functions):
             functions_available = ', '.join([fn['name'] for fn in self._functions])
-            raise MismatchedABI(
+            raise ABIFunctionNotFound(
                 "The function '{}' was not found in this contract's ABI. ".format(function_name),
                 "Here is a list of all of the function names found: ",
                 "{}. ".format(functions_available),
@@ -1369,6 +1376,12 @@ def __getattr__(self, function_name: str) -> Any:
         else:
             return super().__getattribute__(function_name)
 
+    def __hasattr__(self, event_name: str) -> bool:
+        try:
+            return event_name in self.__dict__['_events']
+        except ABIFunctionNotFound:
+            return False
+
     def __call__(
         self, transaction: TxParams=None, block_identifier: BlockIdentifier='latest'
     ) -> 'ContractCaller':

web3/exceptions.py

@@ -78,6 +78,14 @@ class ABIEventFunctionNotFound(AttributeError, MismatchedABI):
     pass
 
 
+class ABIFunctionNotFound(AttributeError, MismatchedABI):
+    """
+    Raised when an attempt is made to access a function
+    that does not exist in the ABI.
+    """
+    pass
+
+
 class FallbackNotFound(Exception):
     """
     Raised when fallback function doesn't exist in contract.