--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/html_norm.py	Sun Oct 02 23:18:43 2022 -0400
@@ -0,0 +1,138 @@
+"""Minimal html parser/normalizer for use in test_templating.
+
+When testing markdown -> html coversion libraries, there are
+gratuitous whitespace changes in generated output that break the
+tests. Use this to try to normalize the generated HTML into something
+that tries to preserve the semantic meaning allowing tests to stop
+breaking.
+
+This is not a complete parsing engine. It supports the Roundup issue
+tracker unit tests so that no third party libraries are needed to run
+the tests. If you find it useful enjoy.
+
+Ideally this would be done by hijacking in some way
+lxml.html.usedoctest to get a liberal parser that will ignore
+whitespace. But that means the user has to install lxml to run the
+tests. Simlarly BeautifulSoup could be used to pretty print the html
+but again then BeautifulSoup would need to be instaled to run the
+tests.
+
+"""
+from html.parser import HTMLParser
+
+try:
+    from htmlentitydefs import name2codepoint
+except ImportError:
+    pass  # assume running under python3, name2codepoint predefined
+
+
+class NormalizingHtmlParser(HTMLParser):
+    """Handle start/end tags and normalize whitespace in data.
+    Strip doctype, comments when passed in.
+
+    Implements normalize method that takes input html and returns a
+    normalized string leaving the instance ready for another call to
+    normalize for another string.
+
+
+    Note that using this rewrites all attributes parsed by HTMLParser
+    into attr="value" form even though HTMLParser accepts other
+    attribute specifiction forms.
+    """
+
+    debug = False  # set to true to enable more verbose output
+
+    current_normalized_string = ""  # accumulate result string
+    preserve_data = False           # if inside pre preserve whitespace
+
+    def handle_starttag(self, tag, attrs):
+        """put tag on new line with attributes.
+           Note valid attributes according to HTMLParser:
+              attrs='single_quote'
+              attrs=noquote
+              attrs="double_quote"
+        """
+        if self.debug: print("Start tag:", tag)
+
+        self.current_normalized_string += "\n<%s" % tag
+
+        for attr in attrs:
+            if self.debug: print("     attr:", attr)
+            self.current_normalized_string += ' %s="%s"' % attr
+
+        self.current_normalized_string += ">"
+
+        if tag == 'pre':
+            self.preserve_data = True
+
+    def handle_endtag(self, tag):
+        if self.debug: print("End tag  :", tag)
+
+        self.current_normalized_string += "\n</%s>" % tag
+
+        if tag == 'pre':
+            self.preserve_data = False
+
+    def handle_data(self, data):
+        if self.debug: print("Data     :", data)
+        if not self.preserve_data:
+            # normalize whitespace remove leading/trailing
+            data = " ".join(data.strip().split())
+
+        if data:
+            self.current_normalized_string += "\n%s" % data
+
+    def handle_comment(self, data):
+        print("Comment  :", data)
+
+    def handle_entityref(self, name):
+        c = chr(name2codepoint[name])
+        if self.debug: print("Named ent:", c)
+
+        self.current_normalized_string += "%s" % c
+
+    def handle_charref(self, name):
+        if name.startswith('x'):
+            c = chr(int(name[1:], 16))
+        else:
+            c = chr(int(name))
+        if self.debug: print("Num ent  :", c)
+
+        self.current_normalized_string += "%s" % c
+
+    def handle_decl(self, data):
+        print("Decl     :", data)
+
+    def reset(self):
+        """wrapper around reset with clearing of csef.current_normalized_string
+           and reset of self.preserve_data
+        """
+        HTMLParser.reset(self)
+        self.current_normalized_string = ""
+        self.preserve_data = False
+
+    def normalize(self, html):
+        self.feed(html)
+        result = self.current_normalized_string
+        self.reset()
+        return result
+
+
+if __name__ == "__main__":
+    parser = NormalizingHtmlParser()
+
+    parser.feed('<div class="markup"><p> paragraph   text with whitespace\n  and more space  <pre><span class="f" data-attr="f">text more text</span></pre></div>')
+    print("\n\ntest1", parser.current_normalized_string)
+
+    parser.reset()
+
+    parser.feed('''<div class="markup">
+       <p> paragraph   text with whitespace\n  and more space  
+       <pre><span class="f" data-attr="f">text \n more text</span></pre>
+    </div>''')
+    print("\n\ntest2", parser.current_normalized_string)
+    parser.reset()
+    print("\n\nnormalize", parser.normalize('''<div class="markup">
+       <p> paragraph   text with whitespace\n  and more space  
+       <pre><span class="f" data-attr="f">text \n more text &lt;</span></pre>
+    </div>'''))