Print a different error if comments are found (#7)

Author: tobywf

README.md

@@ -213,6 +213,10 @@ This makes sense in many cases, but possibly not every case.
 
 ## Changelog
 
+### [0.0.7] - unreleased
+
+* Warn if comments are found/don't treat comments as child elements in error messages
+
 ### [0.0.6] - 2020-03-25
 
 * Allow ignored fields via `init=false` or the `ignored` function

pyproject.toml

@@ -77,7 +77,7 @@ good-names = "_,e,el,ex,f,tp,k,v,ns"
 indent-string = "    "
 
 [tool.taskipy.tasks]
-isort = "isort -v ."
+isort = "isort ."
 black = "black ."
 mypy = "mypy --strict src/xml_dataclasses/ functional/container_test.py"
 pylint = "pylint src/xml_dataclasses/"

src/xml_dataclasses/serde.py

@@ -4,6 +4,7 @@
 from typing import Any, Dict, List, Mapping, Optional, Type, TypeVar, Union
 
 from lxml.builder import ElementMaker  # type: ignore
+from lxml.etree import _Comment as Comment  # type: ignore
 
 from .lxml_utils import strip_ns
 from .resolve_types import (
@@ -44,8 +45,10 @@ def _load_attributes(cls: Type[XmlDataclass], el: Any) -> Mapping[str, str]:
 
 
 def _load_text(info: TextInfo, el: Any) -> Mapping[str, str]:
-    has_child = next(el.iterchildren(), None) is not None
-    if has_child:
+    child = next(el.iterchildren(), None)
+    if child is not None:
+        if isinstance(child, Comment):
+            raise ValueError(f"Element '{el.tag}' contains comments")
         raise ValueError(f"Element '{el.tag}' has child elements (expected text only)")
 
     text = el.text
@@ -64,6 +67,8 @@ def _load_children(cls: Type[XmlDataclass], el: Any) -> Mapping[str, XmlDataclas
     # child elements can be duplicated
     el_children: Dict[str, List[Any]] = defaultdict(list)
     for e in el.iterchildren():
+        if isinstance(e, Comment):
+            raise ValueError(f"Element '{el.tag}' contains comments")
         el_children[e.tag].append(e)
 
     values = {}

tests/load_test.py

@@ -549,3 +549,33 @@ def xml_validate(self) -> None:
     el = etree.fromstring('<foo bar="baz" />')
     with pytest.raises(MyError):
         load(Foo, el, "foo")
+
+
+def test_load_with_child_comment_not_stripped():
+    @xml_dataclass
+    class Foo:
+        __ns__ = None
+        bar: List[Union[Child1, Child2]]
+
+    el = etree.fromstring('<foo><!-- comment --><bar spam="eggs" /></foo>')
+
+    with pytest.raises(ValueError) as exc_info:
+        load(Foo, el, "foo")
+
+    msg = str(exc_info.value)
+    assert "Element 'foo' contains comments" in msg
+
+
+def test_load_with_text_comment_not_stripped():
+    @xml_dataclass
+    class Foo:
+        __ns__ = None
+        value: str = text()
+
+    el = etree.fromstring("<foo>spam<!-- comment -->eggs</foo>")
+
+    with pytest.raises(ValueError) as exc_info:
+        load(Foo, el, "foo")
+
+    msg = str(exc_info.value)
+    assert "Element 'foo' contains comments" in msg