xml.dom.minidom parses comments as nodeValue of a node, if there is no space between the comment and the start tag

[CommunistMountain]

Bug report

Bug description:

"""test.xml
<?xml version="1.0" encoding="UTF-8"?>
<root>
    <foo>not_comment</foo>
    <bar><!--comment_1-->
        <bar/>
    </bar>
    <baz> <!--comment_2-->
        <baz/>
    </baz>
</root>"""
import xml.dom.minidom
tree = xml.dom.minidom.parse('test.xml')
root = tree.documentElement
for child_node in root.childNodes:
    if child_node.localName is not None:
        print(f"{child_node.localName}: '{child_node.firstChild.nodeValue}'")
        # foo: 'not_comment'
        # bar: 'comment_1'
        # baz: ' '

CPython versions tested on:

3.14

Operating systems tested on:

Windows

[ryan-duve]

The behavior is the same for 3.13, 3.12, 3.11 and 3.10.

[serhiy-storchaka]

This is an expected behavior. If the open tag is followed by a comment, the first child node will be Comment. If it is followed by a character data, the first child node will be Text.

Try to print all children:

import xml.dom.minidom
tree = xml.dom.minidom.parseString("""\
<?xml version="1.0" encoding="UTF-8"?>
<root>
    <foo>not_comment</foo>
    <bar><!--comment_1-->
        <bar/>
    </bar>
    <baz> <!--comment_2-->
        <baz/>
    </baz>
</root>""")
root = tree.documentElement
for child_node in root.childNodes:
    if child_node.localName is not None:
        print(child_node.localName, [(type(child_node2).__name__, child_node2.nodeValue) for child_node2 in child_node.childNodes])

The result is:

foo [('Text', 'not_comment')]
bar [('Comment', 'comment_1'), ('Text', '\n        '), ('Element', None), ('Text', '\n    ')]
baz [('Text', ' '), ('Comment', 'comment_2'), ('Text', '\n        '), ('Element', None), ('Text', '\n    ')]