Add test for deletion error, correctly use __delitem__ instead of delete

Author: ajrgrubbs

eip712_structs/struct.py

@@ -287,7 +287,7 @@ def __setitem__(self, key, value):
 
         return self.values.__setitem__(key, value)
 
-    def __delete__(self, instance):
+    def __delitem__(self, _):
         raise TypeError('Deleting entries from an EIP712Struct is not allowed.')
 
 

tests/test_encode_data.py

@@ -240,3 +240,6 @@ class Baz(EIP712Struct):
     with pytest.raises(ValueError):
         # Expects a Foo type, so should throw an error
         bar['f'] = baz
+
+    with pytest.raises(TypeError):
+        del foo['s']