lint/flake8: fix edgy assert use and local var not used.

SQUASHED:

lint/flake8: fix B011 (Do not call assert False...)

...since python -O removes these calls. Instead callers should raise AssertionError().

I did as the tool said, without thinking too much.

lint/flake8: fix F841 (local variable is assigned to but never used).

... When used in try/except blocks, with blank `raise`.

lint/flake8: re-fix F841 (local variable assigned but never used).

Author: veox

eth/consensus/clique/snapshot_manager.py

@@ -182,7 +182,7 @@ def create_snapshot_for(self,
             try:
                 new_snapshot = self.get_snapshot(
                     current_header.block_number, current_header.parent_hash)
-            except SnapshotNotFound as e:
+            except SnapshotNotFound:
                 current_header = self._lookup_header(current_header.parent_hash, cached_parents)
 
                 if is_checkpoint(current_header.block_number, self._epoch_length):
@@ -262,7 +262,7 @@ def get_snapshot_from_db(self, block_hash: Hash32) -> Snapshot:
         except KeyError as e:
             raise SnapshotNotFound(
                 f"Can not get on-disk snapshot for {block_hash!r}"
-            )
+            ) from e
         else:
             return decode_snapshot(encoded_key)
 

eth/vm/base.py

@@ -245,7 +245,7 @@ def apply_all_transactions(
                     previous_header,
                     transaction,
                 )
-            except EVMMissingData as exc:
+            except EVMMissingData:
                 self.state.revert(snapshot)
                 raise
 
@@ -368,7 +368,7 @@ def finalize_block(self, block: BlockAPI) -> BlockAndMetaWitness:
             snapshot = self.state.snapshot()
             try:
                 self._assign_block_rewards(block)
-            except EVMMissingData as exc:
+            except EVMMissingData:
                 self.state.revert(snapshot)
                 raise
             else:

tests/core/vm/test_mainnet_dao_fork.py

@@ -289,4 +289,4 @@ def test_mainnet_dao_fork_header_validation(VM, header, previous_header, valid):
         except ValidationError:
             pass
         else:
-            assert False, "The invalid header %r must fail" % header
+            raise AssertionError("The invalid header %r must fail" % header)

tests/database/test_db_diff.py

@@ -61,7 +61,7 @@ def test_database_api_missing_key_retrieval(db):
     except DiffMissingError as exc:
         assert not exc.is_deleted
     else:
-        assert False, f"key should be missing, but was retrieved as {val}"
+        raise AssertionError(f"key should be missing, but was retrieved as {val}")
 
 
 def test_database_api_missing_key_for_deletion(db):
@@ -73,7 +73,7 @@ def test_database_api_missing_key_for_deletion(db):
     except DiffMissingError as exc:
         assert exc.is_deleted
     else:
-        assert False, f"key should be missing, but was retrieved as {val}"
+        raise AssertionError(f"key should be missing, but was retrieved as {val}")
 
 
 def test_db_diff_equality(db):
@@ -98,7 +98,7 @@ def test_database_api_deleted_key_for_deletion(db):
     except DiffMissingError as exc:
         assert exc.is_deleted
     else:
-        assert False, f"key should be missing, but was retrieved as {val}"
+        raise AssertionError(f"key should be missing, but was retrieved as {val}")
 
 
 @pytest.mark.parametrize(

tests/json-fixtures/test_blockchain.py

@@ -297,7 +297,7 @@ def test_blockchain_fixtures(fixture_data, fixture):
         else:
             try:
                 apply_fixture_block_to_chain(block_fixture, chain)
-            except (TypeError, rlp.DecodingError, rlp.DeserializationError, ValidationError) as err:
+            except (TypeError, rlp.DecodingError, rlp.DeserializationError, ValidationError):
                 # failure is expected on this bad block
                 pass
             else:

tests/json-fixtures/test_virtual_machine.py

@@ -137,7 +137,7 @@ def vm_class(request):
     elif request.param == 'SpuriousDragon':
         pytest.skip('Only the Homestead VM rules are currently supported')
     else:
-        assert False, f"Unsupported VM: {request.param}"
+        raise AssertionError(f"Unsupported VM: {request.param}")
 
 
 def fixture_to_computation(fixture, code, vm):