WIP: html2markdownhtml2markdown

11 files changed, 444 insertions, 24 deletions

diff --git a/Makefile b/Makefile
index 1e23439..65a523c 100644
--- a/Makefile
+++ b/Makefile
@@ -63,8 +63,9 @@ tox-py39: check-poetry ## Run pytest via tox with *python v3.9*
 pytest: check-poetry ## Run pytest
 	poetry run pytest
 
-update-rst-readme: ## update README.rst from README.creole
+update-readmes: ## update README.rst from README.creole
 	poetry run update_rst_readme
+	poetry run update_markdown_readme
 
 publish: ## Release new version to PyPi
 	poetry run publish
diff --git a/README.creole b/README.creole
index c40a487..285a723 100644
--- a/README.creole
+++ b/README.creole
@@ -51,7 +51,7 @@ Convert creole markup to html code:
 {{{
 >>> from creole import creole2html
 >>> creole2html("This is **creole //markup//**")
-u'<p>This is <strong>creole <i>markup</i></strong></p>\n'
+'<p>This is <strong>creole <i>markup</i></strong></p>\n'
 }}}
 
 
@@ -59,8 +59,8 @@ u'<p>This is <strong>creole <i>markup</i></strong></p>\n'
 Convert html code back into creole markup:
 {{{
 >>> from creole import html2creole
->>> html2creole(u'<p>This is <strong>creole <i>markup</i></strong></p>\n')
-u'This is **creole //markup//**'
+>>> html2creole('<p>This is <strong>creole <i>markup</i></strong></p>\n')
+'This is **creole //markup//**'
 }}}
 
 
@@ -69,7 +69,7 @@ Convert ReStructuredText into clean html code (needs [[http://pypi.python.org/py
 {{{
 >>> from creole.rest2html.clean_writer import rest2html
 >>> rest2html(u"A ReSt link to `PyLucid CMS <http://www.pylucid.org>`_ :)")
-u'<p>A ReSt link to <a href="http://www.pylucid.org">PyLucid CMS</a> :)</p>\\n'
+'<p>A ReSt link to <a href="http://www.pylucid.org">PyLucid CMS</a> :)</p>\\n'
 }}}
 (more information: [[https://github.com/jedie/python-creole/wiki/rest2html|rest2html wiki page]])
 
@@ -78,8 +78,8 @@ u'<p>A ReSt link to <a href="http://www.pylucid.org">PyLucid CMS</a> :)</p>\\n'
 Convert html code into ReStructuredText markup:
 {{{
 >>> from creole import html2rest
->>> html2rest(u'<p>This is <strong>ReStructuredText</strong> <em>markup</em>!</p>')
-u'This is **ReStructuredText** *markup*!'
+>>> html2rest('<p>This is <strong>ReStructuredText</strong> <em>markup</em>!</p>')
+'This is **ReStructuredText** *markup*!'
 }}}
 
 
@@ -87,8 +87,18 @@ u'This is **ReStructuredText** *markup*!'
 Convert html code into textile markup
 {{{
 >>> from creole import html2textile
->>> html2textile(u'<p>This is <strong>textile <i>markup</i></strong>!</p>')
-u'This is *textile __markup__*!'
+>>> html2textile('<p>This is <strong>textile <i>markup</i></strong>!</p>')
+'This is *textile __markup__*!'
+}}}
+
+See also: [[http://github.com/jedie/python-creole/blob/master/demo.py]]
+
+== html2markdown ==
+Convert html code into textile markup
+{{{
+>>> from creole import html2markdown
+>>> html2markdown('<p>This is <strong>markdown <i>markup</i></strong>!</p>')
+'This is **markdown _markup_**!'
 }}}
 
 See also: [[http://github.com/jedie/python-creole/blob/master/demo.py]]
@@ -129,6 +139,7 @@ If you have python-creole installed, you will get these simple CLI scripts:
 * html2creole
 * html2rest
 * html2textile
+* html2markdown
 
 Here the {{{--help}}} output from {{{html2creole}}}:
 {{{
@@ -228,6 +239,7 @@ Note: In this case you must install **docutils**! See above.
 = history =
 
 * *dev* - [[https://github.com/jedie/python-creole/compare/v1.4.10...master|compare v1.4.10...master]]
+** NEW: html2markdown
 ** Remove deprecated "parser_kwargs" and "emitter_kwargs"
 ** TBC
 * v1.4.10 - 2021-05-11 - [[https://github.com/jedie/python-creole/compare/v1.4.9...v1.4.10|compare v1.4.9...v1.4.10]]
diff --git a/README.rst b/README.rst
index 23086ef..cf9dd38 100644
--- a/README.rst
+++ b/README.rst
@@ -81,7 +81,7 @@ Convert creole markup to html code:
 
     >>> from creole import creole2html
     >>> creole2html("This is **creole //markup//**")
-    u'<p>This is <strong>creole <i>markup</i></strong></p>\n'
+    '<p>This is <strong>creole <i>markup</i></strong></p>\n'
 
 -----------
 html2creole
@@ -92,8 +92,8 @@ Convert html code back into creole markup:
 ::
 
     >>> from creole import html2creole
-    >>> html2creole(u'<p>This is <strong>creole <i>markup</i></strong></p>\n')
-    u'This is **creole //markup//**'
+    >>> html2creole('<p>This is <strong>creole <i>markup</i></strong></p>\n')
+    'This is **creole //markup//**'
 
 ---------
 rest2html
@@ -105,7 +105,7 @@ Convert ReStructuredText into clean html code (needs `docutils`_):
 
     >>> from creole.rest2html.clean_writer import rest2html
     >>> rest2html(u"A ReSt link to `PyLucid CMS <http://www.pylucid.org>`_ :)")
-    u'<p>A ReSt link to <a href="http://www.pylucid.org">PyLucid CMS</a> :)</p>\\n'
+    '<p>A ReSt link to <a href="http://www.pylucid.org">PyLucid CMS</a> :)</p>\\n'
 
 (more information: `rest2html wiki page <https://github.com/jedie/python-creole/wiki/rest2html>`_)
 
@@ -118,8 +118,8 @@ Convert html code into ReStructuredText markup:
 ::
 
     >>> from creole import html2rest
-    >>> html2rest(u'<p>This is <strong>ReStructuredText</strong> <em>markup</em>!</p>')
-    u'This is **ReStructuredText** *markup*!'
+    >>> html2rest('<p>This is <strong>ReStructuredText</strong> <em>markup</em>!</p>')
+    'This is **ReStructuredText** *markup*!'
 
 ------------
 html2textile
@@ -130,11 +130,25 @@ Convert html code into textile markup
 ::
 
     >>> from creole import html2textile
-    >>> html2textile(u'<p>This is <strong>textile <i>markup</i></strong>!</p>')
-    u'This is *textile __markup__*!'
+    >>> html2textile('<p>This is <strong>textile <i>markup</i></strong>!</p>')
+    'This is *textile __markup__*!'
 
 See also: `http://github.com/jedie/python-creole/blob/master/demo.py <http://github.com/jedie/python-creole/blob/master/demo.py>`_
 
+-------------
+html2markdown
+-------------
+
+Convert html code into textile markup
+
+::
+
+    >>> from creole import html2markdown
+    >>> html2markdown('<p>This is <strong>markdown <i>markup</i></strong>!</p>')
+    'This is **markdown _markup_**!'
+
+See also: `http://github.com/jedie/python-creole/blob/master/demo.py`_
+
 =====================
 Image size additional
 =====================
@@ -184,6 +198,8 @@ If you have python-creole installed, you will get these simple CLI scripts:
 
 * html2textile
 
+* html2markdown
+
 Here the ``--help`` output from ``html2creole``:
 
 ::
@@ -297,6 +313,8 @@ history
 
 * *dev* - `compare v1.4.10...master <https://github.com/jedie/python-creole/compare/v1.4.10...master>`_ 
 
+    * NEW: html2markdown
+
     * Remove deprecated "parser_kwargs" and "emitter_kwargs"
 
     * TBC
@@ -702,4 +720,4 @@ donation
 
 ------------
 
-``Note: this file is generated from README.creole 2021-12-05 16:58:04 with "python-creole"``
\ No newline at end of file
+``Note: this file is generated from README.creole 2021-12-05 17:19:56 with "python-creole"``
\ No newline at end of file
diff --git a/creole/__init__.py b/creole/__init__.py
index 4c22c25..a620b84 100644
--- a/creole/__init__.py
+++ b/creole/__init__.py
@@ -17,6 +17,7 @@ import warnings
 
 from creole.emitter.creol2html_emitter import HtmlEmitter
 from creole.emitter.html2creole_emitter import CreoleEmitter
+from creole.emitter.html2markdown_emitter import MarkdownEmitter
 from creole.emitter.html2rest_emitter import ReStructuredTextEmitter
 from creole.emitter.html2textile_emitter import TextileEmitter
 from creole.parser.creol2html_parser import CreoleParser
@@ -111,6 +112,22 @@ def html2textile(html_string, debug=False,
     return emitter.emit()
 
 
+def html2markdown(html_string, debug=False,
+                  unknown_emit=None
+                  ):
+    """
+    convert html code into markdown markup
+
+    >>> html2markdown('<p>This is <strong>markdown <i>markup</i></strong>!</p>')
+    'This is **markdown _markup_**!'
+    """
+    document_tree = parse_html(html_string, debug=debug)
+
+    # create markdown markup from the document tree
+    emitter = MarkdownEmitter(document_tree, debug=debug, unknown_emit=unknown_emit)
+    return emitter.emit()
+
+
 def html2rest(html_string, debug=False,
               unknown_emit=None
               ):
diff --git a/creole/emitter/html2markdown_emitter.py b/creole/emitter/html2markdown_emitter.py
new file mode 100644
index 0000000..b44b5c1
--- /dev/null
+++ b/creole/emitter/html2markdown_emitter.py
@@ -0,0 +1,155 @@
+"""
+    html -> Markdown Emitter
+    ~~~~~~~~~~~~~~~~~~~~~~
+
+
+    :copyleft: 2021 by python-creole team, see AUTHORS for more details.
+    :license: GNU GPL v3 or above, see LICENSE for more details.
+"""
+
+
+import posixpath
+
+from creole.shared.base_emitter import BaseEmitter
+
+
+class MarkdownEmitter(BaseEmitter):
+    """
+    Build from a document_tree (html2creole.parser.HtmlParser instance) a
+    Markdown markup text.
+    """
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        self.table_head_prefix = '_. '
+        self.table_auto_width = False
+
+    def emit(self):
+        """Emit the document represented by self.root DOM tree."""
+        return self.emit_node(self.root).strip()  # FIXME
+
+    # --------------------------------------------------------------------------
+
+    def indent_text(self, text, spaces):
+        return '\n'.join(f'{spaces}{line}' for line in text.splitlines())
+
+    # --------------------------------------------------------------------------
+
+    def blockdata_pre_emit(self, node):
+        """ pre block -> with newline at the end """
+        text = self.deentity.replace_all(node.content)
+        text = self.indent_text(text, spaces='    ')
+        return text
+
+    def inlinedata_pre_emit(self, node):
+        """ a pre inline block -> no newline at the end """
+        raise NotImplementedError
+        return f'<pre>{self.deentity.replace_all(node.content)}</pre>'
+
+    def blockdata_pass_emit(self, node):
+        raise NotImplementedError
+        return f'{node.content}\n\n'
+
+    # --------------------------------------------------------------------------
+
+    def p_emit(self, node):
+        return f'{self.emit_children(node)}\n\n'
+
+    def headline_emit(self, node):
+        prefix = '#' * node.level
+        return f'{prefix} {self.emit_children(node)}\n\n'
+
+    # --------------------------------------------------------------------------
+
+    def _typeface(self, node, key):
+        return key + self.emit_children(node) + key
+
+    def strong_emit(self, node):
+        return self._typeface(node, key='**')
+
+    def b_emit(self, node):
+        return self._typeface(node, key='**')
+    big_emit = strong_emit
+
+    def i_emit(self, node):
+        return self._typeface(node, key='_')
+
+    def em_emit(self, node):
+        return self._typeface(node, key='_')
+
+    def sup_emit(self, node):
+        return self._typeface(node, key='^')
+
+    def sub_emit(self, node):
+        return self._typeface(node, key='~')
+
+    def del_emit(self, node):
+        return self._typeface(node, key='-')
+
+    def cite_emit(self, node):
+        return self._typeface(node, key='??')
+
+    def ins_emit(self, node):
+        return self._typeface(node, key='+')
+
+    def span_emit(self, node):
+        return self._typeface(node, key='%')
+
+    def code_emit(self, node):
+        return self._typeface(node, key='`')
+
+    def tt_emit(self, node):
+        return self._typeface(node, key='`')
+
+    # --------------------------------------------------------------------------
+
+    def hr_emit(self, node):
+        return '----\n\n'
+
+    def a_emit(self, node):
+        link_text = self.emit_children(node)
+        url = node.attrs['href']
+        return f'[{link_text}]({url})'
+
+    def img_emit(self, node):
+        src = node.attrs['src']
+
+        if src.split(':')[0] == 'data':
+            return ''
+
+        title = node.attrs.get('title', '')
+        alt = node.attrs.get('alt', '')
+        if len(alt) > len(title):  # Use the longest one
+            text = alt
+        else:
+            text = title
+
+        if text == '':  # Use filename as picture text
+            text = posixpath.basename(src)
+
+        return f'![{text}]({src})'
+
+    # --------------------------------------------------------------------------
+
+    # def li_emit(self, node):
+    #     content = self.emit_children(node).strip("\n")
+    #     prefix = '    ' * (node.level - 1)
+    #     result = f"\n{prefix}{content}\n"
+    #     return result
+
+    def _list_emit(self, node, list_type):
+        content=self.emit_children(node)
+        last_kind = self.last.kind if self.last else None
+        print(11111, repr(content), last_kind)
+        content=content.strip()
+        content = f"{list_type} {content}"
+        content = self.indent_text(content, spaces=' '*node.level)
+        content = f"{content}\n"
+        return content
+
+    def ul_emit(self, node):  # Bullet list
+        return self._list_emit(node, list_type='*')
+
+    def ol_emit(self, node):  # Numbered list
+        return self._list_emit(node, list_type='1.')
diff --git a/creole/setup_utils.py b/creole/setup_utils.py
index b2e4dbb..1e6058e 100644
--- a/creole/setup_utils.py
+++ b/creole/setup_utils.py
@@ -21,7 +21,7 @@ from pathlib import Path
 
 from readme_renderer.rst import render
 
-from creole import creole2html, html2rest
+from creole import creole2html, html2markdown, html2rest
 from creole.shared.diff_utils import unified_diff
 from creole.shared.unknown_tags import raise_unknown_node, transparent_unknown_nodes
 
@@ -125,6 +125,30 @@ def _generate_rst_readme(*, creole_readme_path):
     return rest_readme
 
 
+def _generate_markdown_readme(*, creole_readme_path):
+    with creole_readme_path.open('r') as f:
+        creole_readme = f.read().strip()
+
+    # convert creole into html
+    html_readme = creole2html(creole_readme)
+    html_readme_path = creole_readme_path.with_suffix('.html')
+    html_readme_path.write_text(html_readme, encoding='utf-8')
+
+    # convert html to ReSt
+    rest_readme = html2markdown(
+        html_readme,
+        unknown_emit=raise_unknown_node  # raise a error if a unknown node found
+    )
+
+    # Check if generated ReSt is valid, see also:
+    # https://pypi.org/help/#description-content-type
+    rendered = render(rest_readme, stream=sys.stderr)
+    if rendered is None:
+        sys.exit(1)
+
+    return rest_readme
+
+
 def update_rst_readme(package_root, filename='README.creole'):
     """
     Generate README.rst from README.creole
@@ -172,6 +196,53 @@ def update_rst_readme(package_root, filename='README.creole'):
     return rest_readme_path
 
 
+def update_markdown_readme(package_root, filename='README.creole'):
+    """
+    Generate README.md from README.creole
+    """
+    assert isinstance(package_root, Path)
+    assert package_root.is_dir(), f'Directory not found: {package_root}'
+    creole_readme_path = Path(package_root, filename)
+    assert creole_readme_path.is_file(), f'File not found: {creole_readme_path}'
+
+    rest_readme_path = creole_readme_path.with_suffix('.md')
+    print(
+        f'Generate {rest_readme_path.name} from {creole_readme_path.name}',
+        end='...', flush=True
+    )
+
+    markdown_readme = _generate_markdown_readme(creole_readme_path=creole_readme_path)
+
+    # Check if content was changed
+    changed = False
+    with rest_readme_path.open('r') as f:
+        for new_line, old_line in zip(markdown_readme.splitlines(), f):
+            if new_line.rstrip() != old_line.rstrip():
+                changed = True
+                break
+
+    if not changed:
+        # The existing README.rst is up-to-date: Don't change the timestamp
+        print('nothing changed, ok.')
+        return rest_readme_path
+
+    with rest_readme_path.open('w') as f:
+        f.write(markdown_readme)
+
+        # Add a note about generation with modification time from source:
+
+        f.write('\n\n------------\n\n')
+
+        modification_time = creole_readme_path.stat().st_mtime
+        dt = datetime.datetime.fromtimestamp(modification_time)
+        dt = dt.replace(microsecond=0)
+        dt = dt.isoformat(sep=' ')
+        f.write(f'``Note: this file is generated from {filename} {dt} with "python-creole"``')
+
+    print('done.')
+    return rest_readme_path
+
+
 def assert_rst_readme(package_root, filename='README.creole'):
     """
     raise AssertionError if README.rst is not up-to-date.
@@ -179,8 +250,7 @@ def assert_rst_readme(package_root, filename='README.creole'):
     creole_readme_path = Path(package_root, filename)
     rest_readme = _generate_rst_readme(creole_readme_path=creole_readme_path)
     rest_readme_path = creole_readme_path.with_suffix('.rst')
-    with rest_readme_path.open('r') as f:
-        content = f.read()
+    content = rest_readme_path.read_text(encoding='UTF-8')
 
     assert len(content) > 0, f'Empty content in {rest_readme_path}'
     content = content.rsplit('\n', 4)[0]  # remove note about generation with modification time
@@ -190,6 +260,23 @@ def assert_rst_readme(package_root, filename='README.creole'):
         raise AssertionError(f'{rest_readme_path.name} is not up-to-date:\n{diff}')
 
 
+def assert_markdown_readme(package_root, filename='README.creole'):
+    """
+    raise AssertionError if README.md is not up-to-date.
+    """
+    creole_readme_path = Path(package_root, filename)
+    markdown_readme = _generate_markdown_readme(creole_readme_path=creole_readme_path)
+    markdown_readme_path = creole_readme_path.with_suffix('.md')
+    content = markdown_readme_path.read_text(encoding='UTF-8')
+
+    assert len(content) > 0, f'Empty content in {markdown_readme_path}'
+    content = content.rsplit('\n', 4)[0]  # remove note about generation with modification time
+
+    if markdown_readme != content:
+        diff = unified_diff(content, markdown_readme, filename=markdown_readme_path.name)
+        raise AssertionError(f'{markdown_readme_path.name} is not up-to-date:\n{diff}')
+
+
 def update_creole_rst_readme():
     return update_rst_readme(
         package_root=Path(__file__).parent.parent,
@@ -197,5 +284,13 @@ def update_creole_rst_readme():
     )
 
 
+def update_creole_markdown_readme():
+    return update_markdown_readme(
+        package_root=Path(__file__).parent.parent,
+        filename='README.creole'
+    )
+
+
 if __name__ == '__main__':
     update_creole_rst_readme()
+    update_creole_markdown_readme()
diff --git a/creole/shared/base_emitter.py b/creole/shared/base_emitter.py
index 4f7c5f4..35d7f88 100644
--- a/creole/shared/base_emitter.py
+++ b/creole/shared/base_emitter.py
@@ -39,7 +39,6 @@ class BaseEmitter:
 
     def blockdata_pass_emit(self, node):
         return f"{node.content}\n\n"
-        return node.content
 
     # --------------------------------------------------------------------------
 
diff --git a/creole/tests/test_cross_compare_markdown.py b/creole/tests/test_cross_compare_markdown.py
new file mode 100644
index 0000000..5b26ddd
--- /dev/null
+++ b/creole/tests/test_cross_compare_markdown.py
@@ -0,0 +1,59 @@
+"""
+    cross compare markdown unittest
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    Compare all similarities between:
+        * markdown2html (used the python markdown module)
+        * html2markdown
+
+    Note: This only works fine if there is no problematic whitespace handling.
+        In this case, we must test in test_creole2html.py or test_html2creole.py
+
+    :copyleft: 2021 by python-creole team, see AUTHORS for more details.
+    :license: GNU GPL v3 or above, see LICENSE for more details.
+"""
+from inspect import cleandoc
+
+from creole.tests.utils.base_unittest import BaseCreoleTest
+
+
+class CrossCompareTextileTests(BaseCreoleTest):
+    def test_typeface_basic(self):
+        self.cross_compare_markdown(
+            markdown_string="Text attributes _italic_, **bold**, `monospace`.",
+            html_string=(
+                '<p>Text attributes <em>italic</em>,'
+                ' <strong>bold</strong>,'
+                ' <code>monospace</code>.</p>'
+            )
+        )
+
+    def test_lists(self):
+        self.cross_compare_markdown(
+            markdown_string=cleandoc('''
+            Bullet lists nested within numbered list:
+
+              1. fruits
+                 * apple
+                 * banana
+              1. vegetables
+                 - carrot
+                 - broccoli
+            '''),
+            html_string=cleandoc('''
+                <p>Bullet lists nested within numbered list:</p>
+
+                <ol>
+                  <li>fruits <ul>
+                      <li>apple</li>
+                      <li>banana</li>
+                  </ul></li>
+                  <li>vegetables <ul>
+                      <li>carrot</li>
+                      <li>broccoli</li>
+                  </ul></li>
+                </ol>
+            '''),
+            debug=True
+        )
+
diff --git a/creole/tests/test_project_setup.py b/creole/tests/test_project_setup.py
index cb9aa1e..d05ffed 100644
--- a/creole/tests/test_project_setup.py
+++ b/creole/tests/test_project_setup.py
@@ -8,7 +8,7 @@ from poetry_publish.tests.test_project_setup import test_poetry_check as assert_
 from poetry_publish.tests.test_project_setup import test_version as assert_version
 
 from creole import __version__
-from creole.setup_utils import update_rst_readme
+from creole.setup_utils import update_markdown_readme, update_rst_readme
 from creole.tests.constants import CREOLE_PACKAGE_ROOT
 
 
@@ -31,6 +31,17 @@ def test_update_rst_readme(capsys):
     assert str(rest_readme_path).endswith('/README.rst')
 
 
+def test_update_md_readme(capsys):
+    rest_readme_path = update_markdown_readme(
+        package_root=CREOLE_PACKAGE_ROOT, filename='README.creole'
+    )
+    captured = capsys.readouterr()
+    assert captured.out == 'Generate README.md from README.creole...nothing changed, ok.\n'
+    assert captured.err == ''
+    assert isinstance(rest_readme_path, Path)
+    assert str(rest_readme_path).endswith('/README.md')
+
+
 def test_poetry_check():
     """
     Test 'poetry check' output.
diff --git a/creole/tests/utils/base_unittest.py b/creole/tests/utils/base_unittest.py
index e97fac5..ae7ce5e 100644
--- a/creole/tests/utils/base_unittest.py
+++ b/creole/tests/utils/base_unittest.py
@@ -11,9 +11,10 @@
 
 import re
 
+import markdown
 import textile
 
-from creole import creole2html, html2creole, html2rest, html2textile
+from creole import creole2html, html2creole, html2markdown, html2rest, html2textile
 from creole.rest_tools.clean_writer import rest2html
 from creole.tests.utils.utils import MarkupTest
 
@@ -215,6 +216,30 @@ class BaseCreoleTest(MarkupTest):
 
         return textile_string, html_string
 
+    def assert_html2markdown(self, markdown_string, html_string,
+                             strip_lines=False, debug=False, **kwargs):
+        """
+        Check html2markdown
+        """
+        self.assertNotEqual(markdown_string, html_string)
+
+        markdown_string = self._prepare_text(markdown_string)
+        html_string = self._prepare_text(html_string)
+
+        if strip_lines:
+            html_string = strip_html_lines(html_string, strip_lines)
+
+        # compare html -> markdown
+        markdown_string2 = html2markdown(html_string, debug, **kwargs)
+        if debug:
+            print("-" * 79)
+            print(markdown_string2)
+            print("-" * 79)
+
+        self.assertEqual(markdown_string2, markdown_string, msg="html2markdown")
+
+        return markdown_string, html_string
+
     def cross_compare_textile(self, textile_string, html_string,
                               strip_lines=False, debug=False, **kwargs):
         """
@@ -241,6 +266,32 @@ class BaseCreoleTest(MarkupTest):
 
         self.assertEqual(html_string, html, msg="textile2html")
 
+    def cross_compare_markdown(self, markdown_string, html_string,
+                               strip_lines=False, debug=False, **kwargs):
+        """
+            Checks:
+                * html2markdown
+                * markdown2html
+        """
+#        assert isinstance(markdown_string, str)
+#        assert isinstance(html_string, str)
+        self.assertNotEqual(markdown_string, html_string)
+
+        # compare html -> markdown
+        markdown_string, html_string = self.assert_html2markdown(
+            markdown_string, html_string,
+            strip_lines, debug, **kwargs
+        )
+
+        # compare markdown -> html
+        html = markdown.markdown(markdown_string)
+        html = html.replace("<br />", "<br />\n")
+        html = tabs2spaces(html)
+        if strip_lines:
+            html = strip_html_lines(html, strip_lines)
+
+        self.assertEqual(html_string, html, msg="markdown2html")
+
     def assert_html2rest(self, rest_string, html_string,
                          strip_lines=False, debug=False, **kwargs):
         """
diff --git a/pyproject.toml b/pyproject.toml
index 3c3135b..a12eda9 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -52,6 +52,7 @@ flake8 = "*"
 flynt = "*"
 autopep8 = "*"
 pyupgrade = "*"
+markdown = "*"
 
 [tool.poetry.scripts]
 creole2html = "creole.cmdline:cli_creole2html"
@@ -59,6 +60,7 @@ html2creole = "creole.cmdline:cli_html2creole"
 html2rest = "creole.cmdline:cli_html2rest"
 html2textile = "creole.cmdline:cli_html2textile"
 update_rst_readme = "creole.setup_utils:update_creole_rst_readme"
+update_markdown_readme = "creole.setup_utils:update_creole_markdown_readme"
 publish = "creole.publish:publish"
 
 [build-system]