fix: clarify contract call decode failures

newsfragments/1002.bugfix.rst

@@ -0,0 +1,3 @@
+Improve contract call errors when a contract address has code but returns
+insufficient data for ABI decoding, raising ``ContractLogicError`` instead of a
+generic decode failure.

tests/core/contracts/test_contract_call_interface.py

@@ -41,6 +41,7 @@
     ABIReceiveNotFound,
     BadFunctionCallOutput,
     BlockNumberOutOfRange,
+    ContractLogicError,
     InvalidAddress,
     MismatchedABI,
     NameNotFound,
@@ -498,8 +499,10 @@ def test_call_rejects_invalid_ens_name(address_reflector_contract, call):
 def test_call_missing_function(mismatched_math_contract, call):
     # note: contract being called needs to have a fallback function
     # (StringContract in this case)
-    expected_missing_function_error_message = "Could not decode contract function call"
-    with pytest.raises(BadFunctionCallOutput) as exception_info:
+    expected_missing_function_error_message = (
+        "Contract call failed because execution reverted or returned no data."
+    )
+    with pytest.raises(ContractLogicError) as exception_info:
         call(contract=mismatched_math_contract, contract_function="return13")
     assert expected_missing_function_error_message in str(exception_info.value)
 
@@ -1788,8 +1791,10 @@ async def test_async_call_rejects_invalid_ens_name(
 async def test_async_call_missing_function(async_mismatched_math_contract, async_call):
     # note: contract being called needs to have a fallback function
     # (StringContract in this case)
-    expected_missing_function_error_message = "Could not decode contract function call"
-    with pytest.raises(BadFunctionCallOutput) as exception_info:
+    expected_missing_function_error_message = (
+        "Contract call failed because execution reverted or returned no data."
+    )
+    with pytest.raises(ContractLogicError) as exception_info:
         await async_call(
             contract=async_mismatched_math_contract,
             contract_function="return13",

web3/contract/utils.py

@@ -53,6 +53,7 @@
 )
 from web3.exceptions import (
     BadFunctionCallOutput,
+    ContractLogicError,
     Web3ValueError,
 )
 from web3.types import (
@@ -79,6 +80,19 @@
 ACCEPTABLE_EMPTY_STRINGS = ["0x", b"0x", "", b""]
 
 
+def _is_code_missing(code: bytes) -> bool:
+    return code in ACCEPTABLE_EMPTY_STRINGS
+
+
+def _has_insufficient_output_data(
+    return_data: bytes,
+    output_types: Sequence[TypeStr],
+) -> bool:
+    if return_data in ACCEPTABLE_EMPTY_STRINGS:
+        return True
+    return len(return_data) < 32 * len(output_types)
+
+
 @curry
 def format_contract_call_return_data_curried(
     async_w3: Union["AsyncWeb3[Any]", "Web3"],
@@ -201,20 +215,23 @@ def call_contract_function(
     except DecodingError as e:
         # Provide a more helpful error message than the one provided by
         # eth-abi-utils
-        is_missing_code_error = (
-            return_data in ACCEPTABLE_EMPTY_STRINGS
-            and w3.eth.get_code(address) in ACCEPTABLE_EMPTY_STRINGS
-        )
-        if is_missing_code_error:
+        code = w3.eth.get_code(address)
+        if _is_code_missing(code):
             msg = (
                 "Could not transact with/call contract function, is contract "
                 "deployed correctly and chain synced?"
             )
-        else:
+            raise BadFunctionCallOutput(msg) from e
+        if output_types and _has_insufficient_output_data(return_data, output_types):
             msg = (
-                f"Could not decode contract function call to {abi_element_identifier} "
-                f"with return data: {str(return_data)}, output_types: {output_types}"
+                "Contract call failed because execution reverted or returned no "
+                "data."
             )
+            raise ContractLogicError(msg, data=str(return_data)) from e
+        msg = (
+            f"Could not decode contract function call to {abi_element_identifier} "
+            f"with return data: {str(return_data)}, output_types: {output_types}"
+        )
         raise BadFunctionCallOutput(msg) from e
 
     _normalizers = itertools.chain(
@@ -499,20 +516,23 @@ async def async_call_contract_function(
     except DecodingError as e:
         # Provide a more helpful error message than the one provided by
         # eth-abi-utils
-        is_missing_code_error = (
-            return_data in ACCEPTABLE_EMPTY_STRINGS
-            and await async_w3.eth.get_code(address) in ACCEPTABLE_EMPTY_STRINGS
-        )
-        if is_missing_code_error:
+        code = await async_w3.eth.get_code(address)
+        if _is_code_missing(code):
             msg = (
                 "Could not transact with/call contract function, is contract "
                 "deployed correctly and chain synced?"
             )
-        else:
+            raise BadFunctionCallOutput(msg) from e
+        if output_types and _has_insufficient_output_data(return_data, output_types):
             msg = (
-                f"Could not decode contract function call to {abi_element_identifier} "
-                f"with return data: {str(return_data)}, output_types: {output_types}"
+                "Contract call failed because execution reverted or returned no "
+                "data."
             )
+            raise ContractLogicError(msg, data=str(return_data)) from e
+        msg = (
+            f"Could not decode contract function call to {abi_element_identifier} "
+            f"with return data: {str(return_data)}, output_types: {output_types}"
+        )
         raise BadFunctionCallOutput(msg) from e
 
     _normalizers = itertools.chain(