Insert newlines if issue numbers would be inserted inside a code block

src/towncrier/_builder.py

@@ -349,6 +349,17 @@ def render_fragments(
     data: dict[str, dict[str, dict[str, list[str]]]] = {}
     issues_by_category: dict[str, dict[str, list[str]]] = {}
 
+    def maybe_append_newlines(text: str) -> str:
+        # if a newsfragment text ends with a code block, we want to append two newlines
+        # so issue number(s) don't get inserted into the block
+        if re.search(r"::\n\n([ \t]*\S*)*$", text):
+            # We insert one space, the default template inserts another, which results
+            # in the correct indentation given default bullet indentation.
+            # TODO: This breaks on different indentation though, and would require instead
+            # doing this change after the template has been applied.... I thought?
+            return text + "\n\n "
+        return text
+
     for section_name, section_value in fragments.items():
         data[section_name] = {}
         issues_by_category[section_name] = {}
@@ -381,6 +392,7 @@ def render_fragments(
             # for the template, after formatting each issue number
             categories = {}
             for text, issues in entries:
+                text = maybe_append_newlines(text)
                 rendered = [render_issue(issue_format, i) for i in issues]
                 categories[text] = rendered
 

src/towncrier/newsfragments/614.bugfix.rst

@@ -0,0 +1 @@
+Multi-line newsfragments that ends with a code block will now have a newline inserted before appending the link to the issue, to avoid breaking formatting.

src/towncrier/test/test_format.py

@@ -462,3 +462,100 @@ def test_line_wrapping_disabled(self):
             versiondata={"name": "MyProject", "version": "1.0", "date": "never"},
         )
         self.assertEqual(output, expected_output)
+
+    def test_trailing_block(self):
+        """
+        Make sure a newline gets inserted before appending the issue number, if the
+        newsfragment ends with an indented block.
+        """
+
+        fragments = {
+            "": {
+                (
+                    "1",
+                    "feature",
+                    0,
+                ): "text::\n\n    def foo(): ..."
+            }
+        }
+        expected_output = """MyProject 1.0 (never)
+=====================
+
+Features
+--------
+
+- text::
+
+      def foo(): ...
+
+  (#1)
+
+
+"""
+
+        # TODO: I copy-pasted the below lines from previous test, they probably contain
+        # crap that's irrelevant to this test.
+        definitions = {
+            "feature": {"name": "Features", "showcontent": True},
+        }
+        template = read_pkg_resource("templates/default.rst")
+
+        fragments = split_fragments(fragments, definitions)
+        output = render_fragments(
+            template,
+            None,
+            fragments,
+            definitions,
+            ["-", "~"],
+            wrap=True,
+            versiondata={"name": "MyProject", "version": "1.0", "date": "never"},
+        )
+        self.assertEqual(output, expected_output)
+
+    def test_trailing_block_nondefault_bullets(self):
+        """
+        Test insertion of newlines after code block with single-file-no-bullets.
+        """
+        # TODO: I expected this to break with the issue number being indented, but
+        # instead I got an extra newline? Which seems fine?
+
+        fragments = {
+            "": {
+                (
+                    "1",
+                    "feature",
+                    0,
+                ): "text::\n\n    def foo(): ..."
+            }
+        }
+        expected_output = """MyProject 1.0 (never)
+=====================
+
+Features
+--------
+
+text::
+
+      def foo(): ...
+
+
+(#1)
+
+"""
+
+        definitions = {
+            "feature": {"name": "Features", "showcontent": True},
+        }
+        template = read_pkg_resource("templates/single-file-no-bullets.rst")
+
+        fragments = split_fragments(fragments, definitions)
+        output = render_fragments(
+            template,
+            None,
+            fragments,
+            definitions,
+            ["-", "~"],
+            wrap=True,
+            versiondata={"name": "MyProject", "version": "1.0", "date": "never"},
+        )
+        self.assertEqual(output, expected_output)