Add --check-names option to towncrier build

src/towncrier/_builder.py

@@ -17,15 +17,18 @@
 from towncrier._settings.load import Config
 
 
-# Returns issue, category and counter or (None, None, None) if the basename
-# could not be parsed or doesn't contain a valid category.
+# Returns issue, category and counter. But if the basename could not be parsed
+# or doesn't contain a valid category, returns (None, None, None) or raises
+# a ValueError if in strict mode.
 def parse_newfragment_basename(
-    basename: str, frag_type_names: Iterable[str]
+    basename: str, frag_type_names: Iterable[str], strict: bool = False
 ) -> tuple[str, str, int] | tuple[None, None, None]:
     invalid = (None, None, None)
     parts = basename.split(".")
 
     if len(parts) == 1:
+        if strict:
+            raise ValueError(f"Invalid news fragment name: {basename}")
         return invalid
 
     # There are at least 2 parts. Search for a valid category from the second
@@ -53,6 +56,8 @@ def parse_newfragment_basename(
             return issue, category, counter
     else:
         # No valid category found.
+        if strict:
+            raise ValueError(f"Invalid news fragment name: {basename}")
         return invalid
 
 
@@ -106,11 +111,17 @@ def __call__(self, section_directory: str = "") -> str:
 def find_fragments(
     base_directory: str,
     config: Config,
+    strict: bool = False,
 ) -> tuple[Mapping[str, Mapping[tuple[str, str, int], str]], list[tuple[str, str]]]:
     """
     Sections are a dictonary of section names to paths.
     """
     get_section_path = FragmentsPath(base_directory, config)
+    template_filename = (
+        os.path.basename(config.template)
+        if isinstance(config.template, str)
+        else config.template[1]
+    )
 
     content = {}
     fragment_files = []
@@ -129,8 +140,10 @@ def find_fragments(
         file_content = {}
 
         for basename in files:
+            if basename == template_filename:
+                continue
             issue, category, counter = parse_newfragment_basename(
-                basename, config.types
+                basename, config.types, strict
             )
             if category is None:
                 continue

src/towncrier/build.py

@@ -106,6 +106,16 @@ def _validate_answer(ctx: Context, param: Option, value: bool) -> bool:
     help="Do not ask for confirmations. But keep news fragments.",
     callback=_validate_answer,
 )
+@click.option(
+    "--check-names",
+    "check_names",
+    default=False,
+    flag_value=True,
+    help=(
+        "Fail if there are any files in the news fragments directory that "
+        "have invalid names (excluding the template file)."
+    ),
+)
 def _main(
     draft: bool,
     directory: str | None,
@@ -115,6 +125,7 @@ def _main(
     project_date: str | None,
     answer_yes: bool,
     answer_keep: bool,
+    check_names: bool,
 ) -> None:
     """
     Build a combined news file from news fragment.
@@ -129,6 +140,7 @@ def _main(
             project_date,
             answer_yes,
             answer_keep,
+            check_names,
         )
     except ConfigError as e:
         print(e, file=sys.stderr)
@@ -144,6 +156,7 @@ def __main(
     project_date: str | None,
     answer_yes: bool,
     answer_keep: bool,
+    check_names: bool,
 ) -> None:
     """
     The main entry point.
@@ -178,7 +191,9 @@ def __main(
 
     click.echo("Finding news fragments...", err=to_err)
 
-    fragment_contents, fragment_files = find_fragments(base_directory, config)
+    fragment_contents, fragment_files = find_fragments(
+        base_directory, config, strict=check_names
+    )
     fragment_filenames = [filename for (filename, _category) in fragment_files]
 
     click.echo("Rendering news fragments...", err=to_err)

src/towncrier/newsfragments/622.feature.rst

@@ -0,0 +1 @@
+Added an option called ``--check-names`` to ``towncrier build``, that will cause the command to fail if any filenames in the news fragments directory are invalid (excluding the template file).