add utility function to calculate underline size for category names

src/towncrier/_builder.py

@@ -7,6 +7,7 @@
 import os
 import re
 import textwrap
+import unicodedata
 
 from collections import defaultdict
 from fnmatch import fnmatch
@@ -203,6 +204,22 @@ def find_fragments(
     return content, fragment_files
 
 
+def get_underline_size(text: str) -> int:
+    """
+    Given `text` determine the underline size needed for the reStructuredText output.
+
+    Particularly helps determine if an extra underline is needed for wide characters like emojis.
+    """
+    underline_size: int = 0
+    for char in text:
+        if unicodedata.east_asian_width(char) in ("W", "F"):
+            underline_size += 2
+        else:
+            underline_size += 1
+
+    return underline_size
+
+
 def indent(text: str, prefix: str) -> str:
     """
     Adds `prefix` to the beginning of non-empty lines in `text`.
@@ -246,6 +263,10 @@ def split_fragments(
                 # it's recorded.
                 content = ""
 
+            definitions[category]["underline_size"] = get_underline_size(
+                definitions[category]["name"]
+            )
+
             texts = section.setdefault(category, {})
 
             issues = texts.setdefault(content, [])
@@ -411,6 +432,7 @@ def get_indent(text: str) -> str:
         top_underline=top_underline,
         get_indent=get_indent,  # simplify indentation in the jinja template.
         issues_by_category=issues_by_category,
+        versiondata_name_underline_size=get_underline_size(versiondata.get("name", "")),
     )
 
     for line in res.split("\n"):

src/towncrier/build.py

@@ -19,7 +19,12 @@
 
 from towncrier import _git
 
-from ._builder import find_fragments, render_fragments, split_fragments
+from ._builder import (
+    find_fragments,
+    get_underline_size,
+    render_fragments,
+    split_fragments,
+)
 from ._project import get_project_name, get_version
 from ._settings import ConfigError, config_option_help, load_config_from_options
 from ._writer import append_to_newsfile
@@ -234,7 +239,7 @@ def __main(
         if is_markdown:
             parts = [top_line]
         else:
-            parts = [top_line, config.underlines[0] * len(top_line)]
+            parts = [top_line, config.underlines[0] * get_underline_size(top_line)]
         parts.append(rendered)
         content = "\n".join(parts)
     else:

src/towncrier/newsfragments/626.bugfix.rst

@@ -0,0 +1,2 @@
+For reStructuredText format, you can now use emojis in category names.
+In previous versions, the generated underline was not matching the title width.

src/towncrier/templates/default.rst

@@ -1,7 +1,7 @@
 {% if render_title %}
 {% if versiondata.name %}
 {{ versiondata.name }} {{ versiondata.version }} ({{ versiondata.date }})
-{{ top_underline * ((versiondata.name + versiondata.version + versiondata.date)|length + 4)}}
+{{ top_underline * ((versiondata.version + versiondata.date)|length + 4 + versiondata_name_underline_size)}}
 {% else %}
 {{ versiondata.version }} ({{ versiondata.date }})
 {{ top_underline * ((versiondata.version + versiondata.date)|length + 3)}}
@@ -16,7 +16,7 @@
 {% if sections[section] %}
 {% for category, val in definitions.items() if category in sections[section]%}
 {{ definitions[category]['name'] }}
-{{ underline * definitions[category]['name']|length }}
+{{ underline * definitions[category]['underline_size'] }}
 
 {% for text, values in sections[section][category].items() %}
 - {% if text %}{{ text }}{% if values %} ({{ values|join(', ') }}){% endif %}{% else %}{{ values|join(', ') }}{% endif  %}

src/towncrier/templates/hr-between-versions.rst

@@ -1,7 +1,7 @@
 {% if render_title %}
 {% if versiondata.name %}
 {{ versiondata.name }} {{ versiondata.version }} ({{ versiondata.date }})
-{{ top_underline * ((versiondata.name + versiondata.version + versiondata.date)|length + 4)}}
+{{ top_underline * ((versiondata.version + versiondata.date)|length + 4 + versiondata_name_underline_size)}}
 {% else %}
 {{ versiondata.version }} ({{ versiondata.date }})
 {{ top_underline * ((versiondata.version + versiondata.date)|length + 3)}}
@@ -16,7 +16,7 @@
 {% if sections[section] %}
 {% for category, val in definitions.items() if category in sections[section]%}
 {{ definitions[category]['name'] }}
-{{ underline * definitions[category]['name']|length }}
+{{ underline * definitions[category]['underline_size'] }}
 
 {% if definitions[category]['showcontent'] %}
 {% for text, values in sections[section][category].items() %}

src/towncrier/templates/single-file-no-bullets.rst

@@ -1,7 +1,7 @@
 {% if render_title %}
 {% if versiondata.name %}
 {{ versiondata.name }} {{ versiondata.version }} ({{ versiondata.date }})
-{{ top_underline * ((versiondata.name + versiondata.version + versiondata.date)|length + 4)}}
+{{ top_underline * ((versiondata.version + versiondata.date)|length + 4 + versiondata_name_underline_size)}}
 {% else %}
 {{ versiondata.version }} ({{ versiondata.date }})
 {{ top_underline * ((versiondata.version + versiondata.date)|length + 3)}}
@@ -16,7 +16,7 @@
 {% for category, val in definitions.items() if category in sections[section] %}
 
 {{ definitions[category]['name'] }}
-{{ underline * definitions[category]['name']|length }}
+{{ underline * definitions[category]['underline_size'] }}
 
 {% if definitions[category]['showcontent'] %}
 {% for text, values in sections[section][category].items() %}

src/towncrier/test/helpers.py

@@ -29,7 +29,7 @@ def write(path: str | Path, contents: str, dedent: bool = False) -> None:
     p.parent.mkdir(parents=True, exist_ok=True)
     if dedent:
         contents = textwrap.dedent(contents)
-    p.write_text(contents)
+    p.write_text(contents, encoding="utf-8")
 
 
 def read_pkg_resource(path: str) -> str:
@@ -65,9 +65,9 @@ def setup_simple_project(
         config = "[tool.towncrier]\n" 'package = "foo"\n' + extra_config
     else:
         config = textwrap.dedent(config)
-    Path(pyproject_path).write_text(config)
+    Path(pyproject_path).write_text(config, encoding="utf-8")
     Path("foo").mkdir()
-    Path("foo/__init__.py").write_text('__version__ = "1.2.3"\n')
+    Path("foo/__init__.py").write_text('__version__ = "1.2.3"\n', encoding="utf-8")
 
     if mkdir_newsfragments:
         Path("foo/newsfragments").mkdir()

src/towncrier/test/test_build.py

@@ -1398,6 +1398,62 @@ def test_default_start_string_markdown(self, runner):
 
         self.assertEqual(expected_output, output)
 
+    @with_project(
+        config="""
+        [tool.towncrier]
+        name = "🍫 FooBar"
+
+          [[tool.towncrier.type]]
+          directory = "bugfix"
+          name = "🐛 Bugfixes"
+          showcontent = true
+        """
+    )
+    def test_underline_size_unicode(self, runner):
+        """
+        The news file can be generated for project names,
+        and categories that contains emoji in their names.
+
+        This is a test for generating the RST section
+        underline to meet the docutils requirements.
+        """
+        os.mkdir("newsfragments")
+        with open("newsfragments/321.bugfix", "w") as f:
+            f.write("Squashed a bug")
+
+        result = runner.invoke(
+            _main,
+            [
+                "--version=7.8.9",
+                "--date=01-01-2001",
+                "--draft",
+            ],
+        )
+
+        expected_output = dedent(
+            """\
+            Loading template...
+            Finding news fragments...
+            Rendering news fragments...
+            Draft only -- nothing has been written.
+            What is seen below is what would be written.
+
+            🍫 FooBar 7.8.9 (01-01-2001)
+            ============================
+
+            🐛 Bugfixes
+            -----------
+
+            - Squashed a bug (#321)
+
+
+
+        """
+        )
+
+        self.assertEqual(0, result.exit_code, result.output)
+        self.assertEqual(expected_output, result.output)
+
     @with_project(
         config="""
         [tool.towncrier]

src/towncrier/test/test_builder.py

@@ -5,7 +5,7 @@
 
 from twisted.trial.unittest import TestCase
 
-from .._builder import parse_newfragment_basename, render_fragments
+from .._builder import get_underline_size, parse_newfragment_basename, render_fragments
 
 
 class TestParseNewsfragmentBasename(TestCase):
@@ -41,6 +41,14 @@ def test_counter_with_extension(self):
             ("123", "feature", 1),
         )
 
+    def test_get_underline_size_ascii(self):
+        """Determine underline size for normal ASCII strings."""
+        assert get_underline_size("bugfixes") == 8
+
+    def test_get_underline_size_wide_character(self):
+        """Determine underline size for strings with wide characters."""
+        assert get_underline_size("🐛 Bugfixes") == 11
+
     def test_ignores_extension(self):
         """File extensions are ignored."""
         self.assertEqual(