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buildmimetree.py: add --related-to-html-only
[etc/neomutt.git] / .config / neomutt / buildmimetree.py
index f7d7c56b8f8861aa6b327821dc0ba9f0fb5058f7..36298ca0247294bdf6ffafc5f325582c2462b809 100755 (executable)
@@ -23,8 +23,8 @@
 #   - python3-markdown
 # Optional:
 #   - pytest
-#   - Pynliner
-#   - Pygments, if installed, then syntax highlighting is enabled
+#   - Pynliner, provides --css-file and thus inline styling of HTML output
+#   - Pygments, then syntax highlighting for fenced code is enabled
 #
 # Latest version:
 #   https://git.madduck.net/etc/neomutt.git/blob_plain/HEAD:/.config/neomutt/buildmimetree.py
@@ -63,7 +63,23 @@ def parse_cli_args(*args, **kwargs):
         "--extensions",
         type=str,
         default="",
-        help="Markdown extension to use (comma-separated list)"
+        help="Markdown extension to use (comma-separated list)",
+    )
+
+    if _PYNLINER:
+        parser.add_argument(
+            "--css-file",
+            type=str,
+            default="",
+            help="CSS file to merge with the final HTML",
+        )
+    else:
+        parser.set_defaults(css_file=None)
+
+    parser.add_argument(
+        "--related-to-html-only",
+        action="store_true",
+        help="Make related content be sibling to HTML parts only"
     )
 
     parser.add_argument(
@@ -85,12 +101,16 @@ def parse_cli_args(*args, **kwargs):
     )
 
     subp = parser.add_subparsers(help="Sub-command parsers", dest="mode")
-    massage_p = subp.add_parser("massage", help="Massaging phase (internal use)")
+    massage_p = subp.add_parser(
+        "massage", help="Massaging phase (internal use)"
+    )
 
     massage_p.add_argument(
         "--write-commands-to",
+        "-o",
         metavar="PATH",
         dest="cmdpath",
+        required=True,
         help="Temporary file path to write commands to",
     )
 
@@ -158,11 +178,15 @@ class InlineImageExtension(Extension):
         return self._images
 
 
-def markdown_with_inline_image_support(text, *, extensions=None):
+def markdown_with_inline_image_support(
+    text, *, extensions=None, extension_configs=None
+):
     inline_image_handler = InlineImageExtension()
     extensions = extensions or []
     extensions.append(inline_image_handler)
-    mdwn = markdown.Markdown(extensions=extensions)
+    mdwn = markdown.Markdown(
+        extensions=extensions, extension_configs=extension_configs
+    )
     htmltext = mdwn.convert(text)
 
     images = inline_image_handler.get_images()
@@ -177,6 +201,38 @@ def markdown_with_inline_image_support(text, *, extensions=None):
     return text, htmltext, images
 
 
+# [ CSS STYLING ] #############################################################
+
+try:
+    import pynliner
+
+    _PYNLINER = True
+
+except ImportError:
+    _PYNLINER = False
+
+try:
+    from pygments.formatters import get_formatter_by_name
+
+    _CODEHILITE_CLASS = "codehilite"
+
+    _PYGMENTS_CSS = get_formatter_by_name(
+        "html", style="default"
+    ).get_style_defs(f".{_CODEHILITE_CLASS}")
+
+except ImportError:
+    _PYGMENTS_CSS = None
+
+
+def apply_styling(html, css):
+    return (
+        pynliner.Pynliner()
+        .from_string(html)
+        .with_cssString("\n".join(s for s in [_PYGMENTS_CSS, css] if s))
+        .run()
+    )
+
+
 # [ PARTS GENERATION ] ########################################################
 
 
@@ -202,6 +258,9 @@ class Multipart(
     def __str__(self):
         return f"<multipart/{self.subtype}> children={len(self.children)}"
 
+    def __hash__(self):
+        return hash(str(self.subtype) + "".join(str(self.children)))
+
 
 def filewriter_fn(path, content, mode="w", **kwargs):
     with open(path, mode, **kwargs) as out_f:
@@ -213,6 +272,9 @@ def collect_inline_images(
 ):
     relparts = []
     for path, info in images.items():
+        if path.startswith("cid:"):
+            continue
+
         data = request.urlopen(path)
 
         mimetype = data.headers["Content-Type"]
@@ -223,7 +285,12 @@ def collect_inline_images(
         filewriter_fn(path, data.read(), "w+b")
 
         relparts.append(
-            Part(*mimetype.split("/"), path, cid=info.cid, desc=f"Image: {info.desc}")
+            Part(
+                *mimetype.split("/"),
+                path,
+                cid=info.cid,
+                desc=f"Image: {info.desc}",
+            )
         )
 
     return relparts
@@ -233,12 +300,20 @@ def convert_markdown_to_html(
     origtext,
     draftpath,
     *,
+    cssfile=None,
+    related_to_html_only=True,
     filewriter_fn=filewriter_fn,
     tempdir=None,
     extensions=None,
+    extension_configs=None,
 ):
+    # TODO extension_configs need to be handled differently
+    extension_configs = extension_configs or {}
+    extension_configs.setdefault("pymdownx.highlight", {})
+    extension_configs["pymdownx.highlight"]["css_class"] = _CODEHILITE_CLASS
+
     origtext, htmltext, images = markdown_with_inline_image_support(
-        origtext, extensions=extensions
+        origtext, extensions=extensions, extension_configs=extension_configs
     )
 
     filewriter_fn(draftpath, origtext, encoding="utf-8")
@@ -246,79 +321,106 @@ def convert_markdown_to_html(
         "text", "plain", draftpath, "Plain-text version", orig=True
     )
 
+    htmltext = apply_styling(htmltext, cssfile)
+
     htmlpath = draftpath.with_suffix(".html")
     filewriter_fn(
         htmlpath, htmltext, encoding="utf-8", errors="xmlcharrefreplace"
     )
     htmlpart = Part("text", "html", htmlpath, "HTML version")
 
-    altpart = Multipart(
-        "alternative", [textpart, htmlpart], "Group of alternative content"
-    )
-
     imgparts = collect_inline_images(
         images, tempdir=tempdir, filewriter_fn=filewriter_fn
     )
-    if imgparts:
+
+    if related_to_html_only:
+        # If there are inline image part, they will be contained within a
+        # multipart/related part along with the HTML part only
+        if imgparts:
+            # replace htmlpart with a multipart/related container of the HTML
+            # parts and the images
+            htmlpart = Multipart(
+                "relative", [htmlpart] + imgparts, "Group of related content"
+            )
+
         return Multipart(
-            "relative", [altpart] + imgparts, "Group of related content"
+            "alternative", [textpart, htmlpart], "Group of alternative content"
         )
+
     else:
-        return altpart
+        # If there are inline image part, they will be siblings to the
+        # multipart/alternative tree within a multipart/related part
+        altpart = Multipart(
+            "alternative", [textpart, htmlpart], "Group of alternative content"
+        )
+        if imgparts:
+            return Multipart(
+                "relative", [altpart] + imgparts, "Group of related content"
+            )
+        else:
+            return altpart
 
 
 class MIMETreeDFWalker:
     def __init__(self, *, visitor_fn=None, debug=False):
-        self._visitor_fn = visitor_fn
+        self._visitor_fn = visitor_fn or self._echovisit
         self._debug = debug
 
+    def _echovisit(self, node, ancestry, debugprint):
+        debugprint(f"node={node} ancestry={ancestry}")
+
     def walk(self, root, *, visitor_fn=None):
         """
         Recursive function to implement a depth-dirst walk of the MIME-tree
         rooted at `root`.
         """
-
         if isinstance(root, list):
-            root = Multipart("mixed", children=root)
+            if len(root) > 1:
+                root = Multipart("mixed", children=root)
+            else:
+                root = root[0]
 
         self._walk(
             root,
-            stack=[],
+            ancestry=[],
             visitor_fn=visitor_fn or self._visitor_fn,
         )
 
-    def _walk(self, node, *, stack, visitor_fn):
+    def _walk(self, node, *, ancestry, visitor_fn):
         # Let's start by enumerating the parts at the current level. At the
-        # root level, stack will be the empty list, and we expect a multipart/*
-        # container at this level. Later, e.g. within a mutlipart/alternative
-        # container, the subtree will just be the alternative parts, while the
-        # top of the stack will be the multipart/alternative container, which
-        # we will process after the following loop.
-
-        lead = f"{'| '*len(stack)}|-"
+        # root level, ancestry will be the empty list, and we expect a
+        # multipart/* container at this level. Later, e.g. within a
+        # mutlipart/alternative container, the subtree will just be the
+        # alternative parts, while the top of the ancestry will be the
+        # multipart/alternative container, which we will process after the
+        # following loop.
+
+        lead = f"{'│ '*len(ancestry)}"
         if isinstance(node, Multipart):
             self.debugprint(
-                f"{lead}{node} parents={[s.subtype for s in stack]}"
+                f"{lead}├{node} ancestry={[s.subtype for s in ancestry]}"
             )
 
-            # Depth-first, so push the current container onto the stack,
-            # then descend …
-            stack.append(node)
-            self.debugprint("| " * (len(stack) + 1))
+            # Depth-first, so push the current container onto the ancestry
+            # stack, then descend …
+            ancestry.append(node)
+            self.debugprint(lead + "│ " * 2)
             for child in node.children:
                 self._walk(
                     child,
-                    stack=stack,
+                    ancestry=ancestry,
                     visitor_fn=visitor_fn,
                 )
-            self.debugprint("| " * len(stack))
-            assert stack.pop() == node
+            assert ancestry.pop() == node
 
         else:
-            self.debugprint(f"{lead}{node}")
+            self.debugprint(f"{lead}├{node}")
+
+        if False and ancestry:
+            self.debugprint(lead[:-1] + " │")
 
         if visitor_fn:
-            visitor_fn(node, stack, debugprint=self.debugprint)
+            visitor_fn(node, ancestry, debugprint=self.debugprint)
 
     def debugprint(self, s, **kwargs):
         if self._debug:
@@ -401,7 +503,9 @@ def do_massage(
     cmd_f,
     *,
     extensions=None,
+    cssfile=None,
     converter=convert_markdown_to_html,
+    related_to_html_only=True,
     only_build=False,
     tempdir=None,
     debug_commands=False,
@@ -426,17 +530,26 @@ def do_massage(
     cmds.flush()
 
     extensions = extensions.split(",") if extensions else []
-    tree = converter(draft_f.read(), draftpath, tempdir=tempdir, extensions=extensions)
+    tree = converter(
+        draft_f.read(),
+        draftpath,
+        cssfile=cssfile,
+        related_to_html_only=related_to_html_only,
+        tempdir=tempdir,
+        extensions=extensions,
+    )
 
     mimetree = MIMETreeDFWalker(debug=debug_walk)
 
-    def visitor_fn(item, stack, *, debugprint=None):
+    state = dict(pos=1, tags={}, parts=1)
+
+    def visitor_fn(item, ancestry, *, debugprint=None):
         """
         Visitor function called for every node (part) of the MIME tree,
         depth-first, and responsible for telling NeoMutt how to assemble
         the tree.
         """
-        KILL_LINE=r'\Ca\Ck'
+        KILL_LINE = r"\Ca\Ck"
 
         if isinstance(item, Part):
             # We've hit a leaf-node, i.e. an alternative or a related part
@@ -447,13 +560,27 @@ def do_massage(
                 # The original source already exists in the NeoMutt tree, but
                 # the underlying file may have been modified, so we need to
                 # update the encoding, but that's it:
+                cmds.push("<first-entry>")
                 cmds.push("<update-encoding>")
+
+                # We really just need to be able to assume that at this point,
+                # NeoMutt is at position 1, and that we've processed only this
+                # part so far. Nevermind about actual attachments, we can
+                # safely ignore those as they stay at the end.
+                assert state["pos"] == 1
+                assert state["parts"] == 1
             else:
                 # … whereas all other parts need to be added, and they're all
                 # considered to be temporary and inline:
                 cmds.push(f"<attach-file>{item.path}<enter>")
                 cmds.push("<toggle-unlink><toggle-disposition>")
 
+                # This added a part at the end of the list of parts, and that's
+                # just how many parts we've seen so far, so it's position in
+                # the NeoMutt compose list is the count of parts
+                state["parts"] += 1
+                state["pos"] = state["parts"]
+
             # If the item (including the original) comes with additional
             # information, then we might just as well update the NeoMutt
             # tree now:
@@ -462,29 +589,47 @@ def do_massage(
 
         elif isinstance(item, Multipart):
             # This node has children, but we already visited them (see
-            # above), and so they have been tagged in NeoMutt's compose
-            # window. Now it's just a matter of telling NeoMutt to do the
-            # appropriate grouping:
+            # above). The tags dictionary of State should contain a list of
+            # their positions in the NeoMutt compose window, so iterate those
+            # and tag the parts there:
+            for tag in state["tags"][item]:
+                cmds.push(f"<jump>{tag}<enter><tag-entry>")
+
             if item.subtype == "alternative":
                 cmds.push("<group-alternatives>")
             elif item.subtype in ("relative", "related"):
                 cmds.push("<group-related>")
             elif item.subtype == "multilingual":
                 cmds.push("<group-multilingual>")
+            else:
+                raise NotImplementedError(
+                    f"Handling of multipart/{item.subtype} is not implemented"
+                )
+
+            state["pos"] -= len(state["tags"][item]) - 1
+            state["parts"] += 1
+            del state["tags"][item]
 
         else:
             # We should never get here
-            assert not "is valid part"
+            raise RuntimeError(f"Type {type(item)} is unexpected: {item}")
 
         # If the item has a description, we might just as well add it
         if item.desc:
             cmds.push(f"<edit-description>{KILL_LINE}{item.desc}<enter>")
 
-        # Finally, if we're at non-root level, tag the new container,
-        # as it might itself be part of a container, to be processed
-        # one level up:
-        if stack:
-            cmds.push("<tag-entry>")
+        if ancestry:
+            # If there's an ancestry, record the current (assumed) position in
+            # the NeoMutt compose window as needed-to-tag by our direct parent
+            # (i.e. the last item of the ancestry)
+            state["tags"].setdefault(ancestry[-1], []).append(state["pos"])
+
+            lead = "│ " * (len(ancestry) + 1) + "* "
+            debugprint(
+                f"{lead}ancestry={[a.subtype for a in ancestry]}\n"
+                f"{lead}children_positions={state['tags'][ancestry[-1]]}\n"
+                f"{lead}pos={state['pos']}, parts={state['parts']}"
+            )
 
     # -----------------
     # End of visitor_fn
@@ -527,6 +672,8 @@ if __name__ == "__main__":
                 pathlib.Path(args.MAILDRAFT),
                 cmd_f,
                 extensions=args.extensions,
+                cssfile=args.css_file,
+                related_to_html_only=args.related_to_html_only,
                 only_build=args.only_build,
                 tempdir=args.tempdir,
                 debug_commands=args.debug_commands,
@@ -596,7 +743,7 @@ try:
             assert lines[5] in lines_out[7]
 
         @pytest.fixture
-        def basic_mime_tree(self):
+        def mime_tree_related_to_alternative(self):
             return Multipart(
                 "relative",
                 children=[
@@ -621,15 +768,49 @@ try:
                 desc="Related",
             )
 
-        def test_MIMETreeDFWalker_depth_first_walk(self, basic_mime_tree):
+        @pytest.fixture
+        def mime_tree_related_to_html(self):
+            return Multipart(
+                "alternative",
+                children=[
+                    Part(
+                        "text",
+                        "plain",
+                        "part.txt",
+                        desc="Plain",
+                        orig=True,
+                    ),
+                    Multipart(
+                        "relative",
+                        children=[
+                            Part("text", "html", "part.html", desc="HTML"),
+                            Part(
+                                "text",
+                                "png",
+                                "logo.png",
+                                cid="logo.png",
+                                desc="Logo",
+                            ),
+                        ],
+                        desc="Related",
+                    ),
+                ],
+                desc="Alternative",
+            )
+
+        def test_MIMETreeDFWalker_depth_first_walk(
+            self, mime_tree_related_to_alternative
+        ):
             mimetree = MIMETreeDFWalker()
 
             items = []
 
-            def visitor_fn(item, stack, debugprint):
-                items.append((item, len(stack)))
+            def visitor_fn(item, ancestry, debugprint):
+                items.append((item, len(ancestry)))
 
-            mimetree.walk(basic_mime_tree, visitor_fn=visitor_fn)
+            mimetree.walk(
+                mime_tree_related_to_alternative, visitor_fn=visitor_fn
+            )
             assert len(items) == 5
             assert items[0][0].subtype == "plain"
             assert items[0][1] == 2
@@ -642,26 +823,29 @@ try:
             assert items[4][0].subtype == "relative"
             assert items[4][1] == 0
 
-        def test_MIMETreeDFWalker_list_to_mixed(self, basic_mime_tree):
+        def test_MIMETreeDFWalker_list_to_mixed(self, const1):
             mimetree = MIMETreeDFWalker()
             items = []
 
-            def visitor_fn(item, stack, debugprint):
+            def visitor_fn(item, ancestry, debugprint):
                 items.append(item)
 
-            mimetree.walk([basic_mime_tree], visitor_fn=visitor_fn)
+            p = Part("text", "plain", const1)
+            mimetree.walk([p], visitor_fn=visitor_fn)
+            assert items[-1].subtype == "plain"
+            mimetree.walk([p, p], visitor_fn=visitor_fn)
             assert items[-1].subtype == "mixed"
 
         def test_MIMETreeDFWalker_visitor_in_constructor(
-            self, basic_mime_tree
+            self, mime_tree_related_to_alternative
         ):
             items = []
 
-            def visitor_fn(item, stack, debugprint):
+            def visitor_fn(item, ancestry, debugprint):
                 items.append(item)
 
             mimetree = MIMETreeDFWalker(visitor_fn=visitor_fn)
-            mimetree.walk(basic_mime_tree)
+            mimetree.walk(mime_tree_related_to_alternative)
             assert len(items) == 5
 
         @pytest.fixture
@@ -669,7 +853,14 @@ try:
             return StringIO(text or const1)
 
         def test_do_massage_basic(self, const1, string_io, capsys):
-            def converter(drafttext, draftpath, extensions, tempdir):
+            def converter(
+                drafttext,
+                draftpath,
+                cssfile,
+                related_to_html_only,
+                extensions,
+                tempdir,
+            ):
                 return Part("text", "plain", draftpath, orig=True)
 
             do_massage(
@@ -687,14 +878,22 @@ try:
             assert "unset my_edit_headers" == lines.pop(0)
             assert "send-message" in lines.pop(0)
             assert "update-encoding" in lines.pop(0)
+            assert "first-entry" in lines.pop(0)
             assert "source 'rm -f " in lines.pop(0)
             assert "unset my_mdwn_postprocess_cmd_file" == lines.pop(0)
 
         def test_do_massage_fulltree(
-            self, string_io, const1, basic_mime_tree, capsys
+            self, string_io, const1, mime_tree_related_to_alternative, capsys
         ):
-            def converter(drafttext, draftpath, extensions, tempdir):
-                return basic_mime_tree
+            def converter(
+                drafttext,
+                draftpath,
+                cssfile,
+                related_to_html_only,
+                extensions,
+                tempdir,
+            ):
+                return mime_tree_related_to_alternative
 
             do_massage(
                 draft_f=string_io,
@@ -704,26 +903,27 @@ try:
             )
 
             captured = capsys.readouterr()
-            lines = captured.out.splitlines()[4:]
-            assert "send-message" in lines.pop(0)
-            assert "Related" in lines.pop(0)
-            assert "group-related" in lines.pop(0)
-            assert "tag-entry" in lines.pop(0)
-            assert "Logo" in lines.pop(0)
-            assert "content-id" in lines.pop(0)
-            assert "toggle-unlink" in lines.pop(0)
-            assert "logo.png" in lines.pop(0)
-            assert "tag-entry" in lines.pop(0)
-            assert "Alternative" in lines.pop(0)
-            assert "group-alternatives" in lines.pop(0)
-            assert "tag-entry" in lines.pop(0)
-            assert "HTML" in lines.pop(0)
-            assert "toggle-unlink" in lines.pop(0)
-            assert "part.html" in lines.pop(0)
-            assert "tag-entry" in lines.pop(0)
-            assert "Plain" in lines.pop(0)
-            assert "update-encoding" in lines.pop(0)
-            assert len(lines) == 2
+            lines = captured.out.splitlines()[4:-2]
+            assert "first-entry" in lines.pop()
+            assert "update-encoding" in lines.pop()
+            assert "Plain" in lines.pop()
+            assert "part.html" in lines.pop()
+            assert "toggle-unlink" in lines.pop()
+            assert "HTML" in lines.pop()
+            assert "jump>1" in lines.pop()
+            assert "jump>2" in lines.pop()
+            assert "group-alternatives" in lines.pop()
+            assert "Alternative" in lines.pop()
+            assert "logo.png" in lines.pop()
+            assert "toggle-unlink" in lines.pop()
+            assert "content-id" in lines.pop()
+            assert "Logo" in lines.pop()
+            assert "jump>1" in lines.pop()
+            assert "jump>4" in lines.pop()
+            assert "group-related" in lines.pop()
+            assert "Related" in lines.pop()
+            assert "send-message" in lines.pop()
+            assert len(lines) == 0
 
         @pytest.fixture
         def fake_filewriter(self):
@@ -743,9 +943,7 @@ try:
         def markdown_non_converter(self, const1, const2):
             return lambda s, text: f"{const1}{text}{const2}"
 
-        def test_converter_tree_basic(
-            self, const1, const2, fake_filewriter, markdown_non_converter
-        ):
+        def test_converter_tree_basic(self, const1, const2, fake_filewriter):
             path = pathlib.Path(const2)
             tree = convert_markdown_to_html(
                 const1, path, filewriter_fn=fake_filewriter
@@ -864,15 +1062,53 @@ try:
             text = f"![inline base64 image]({test_png})"
             path = pathlib.Path(const1)
             tree = convert_markdown_to_html(
-                text, path, filewriter_fn=fake_filewriter
+                text,
+                path,
+                filewriter_fn=fake_filewriter,
+                related_to_html_only=False,
             )
-
             assert tree.subtype == "relative"
+            assert tree.children[0].subtype == "alternative"
             assert tree.children[1].subtype == "png"
             written = fake_filewriter.pop()
             assert tree.children[1].path == written[0]
             assert written[1] == request.urlopen(test_png).read()
 
+        def test_converter_tree_inline_image_base64_related_to_html(
+            self, test_png, const1, fake_filewriter
+        ):
+            text = f"![inline base64 image]({test_png})"
+            path = pathlib.Path(const1)
+            tree = convert_markdown_to_html(
+                text,
+                path,
+                filewriter_fn=fake_filewriter,
+                related_to_html_only=True,
+            )
+            assert tree.subtype == "alternative"
+            assert tree.children[1].subtype == "relative"
+            assert tree.children[1].children[1].subtype == "png"
+            written = fake_filewriter.pop()
+            assert tree.children[1].children[1].path == written[0]
+            assert written[1] == request.urlopen(test_png).read()
+
+        def test_converter_tree_inline_image_cid(
+            self, const1, fake_filewriter
+        ):
+            text = f"![inline base64 image](cid:{const1})"
+            path = pathlib.Path(const1)
+            tree = convert_markdown_to_html(
+                text,
+                path,
+                filewriter_fn=fake_filewriter,
+                related_to_html_only=False,
+            )
+            assert len(tree.children) == 2
+            assert tree.children[0].cid != const1
+            assert tree.children[0].type != "image"
+            assert tree.children[1].cid != const1
+            assert tree.children[1].type != "image"
+
         def test_inline_image_collection(
             self, test_png, const1, const2, fake_filewriter
         ):
@@ -889,5 +1125,64 @@ try:
             assert relparts[0].cid == const1
             assert relparts[0].desc.endswith(const2)
 
+        def test_apply_stylesheet(self):
+            if _PYNLINER:
+                html = "<p>Hello, world!</p>"
+                css = "p { color:red }"
+                out = apply_styling(html, css)
+                assert 'p style="color' in out
+
+        def test_apply_stylesheet_pygments(self):
+            if _PYGMENTS_CSS:
+                html = (
+                    f'<div class="{_CODEHILITE_CLASS}">'
+                    "<pre>def foo():\n    return</pre></div>"
+                )
+                out = apply_styling(html, _PYGMENTS_CSS)
+                assert f'{_CODEHILITE_CLASS}" style="' in out
+
+        def test_mime_tree_relative_within_alternative(
+            self, string_io, const1, capsys, mime_tree_related_to_html
+        ):
+            def converter(
+                drafttext,
+                draftpath,
+                cssfile,
+                related_to_html_only,
+                extensions,
+                tempdir,
+            ):
+                return mime_tree_related_to_html
+
+            do_massage(
+                draft_f=string_io,
+                draftpath=const1,
+                cmd_f=sys.stdout,
+                converter=converter,
+            )
+
+            captured = capsys.readouterr()
+            lines = captured.out.splitlines()[4:-2]
+            assert "first-entry" in lines.pop()
+            assert "update-encoding" in lines.pop()
+            assert "Plain" in lines.pop()
+            assert "part.html" in lines.pop()
+            assert "toggle-unlink" in lines.pop()
+            assert "HTML" in lines.pop()
+            assert "logo.png" in lines.pop()
+            assert "toggle-unlink" in lines.pop()
+            assert "content-id" in lines.pop()
+            assert "Logo" in lines.pop()
+            assert "jump>2" in lines.pop()
+            assert "jump>3" in lines.pop()
+            assert "group-related" in lines.pop()
+            assert "Related" in lines.pop()
+            assert "jump>1" in lines.pop()
+            assert "jump>2" in lines.pop()
+            assert "group-alternative" in lines.pop()
+            assert "Alternative" in lines.pop()
+            assert "send-message" in lines.pop()
+            assert len(lines) == 0
+
 except ImportError:
     pass