New -N/--add-eof-newline option to add ending NL

src/xml_fmt/__main__.py

@@ -25,6 +25,7 @@ class Options(Namespace):
 
     indent: str
     expand_empty_elements: bool
+    add_eof_newline: bool
 
 
 def run(args: Sequence[str] | None = None) -> int:
@@ -76,6 +77,12 @@ def _build_cli() -> ArgumentParser:
         action="store_true",
         help="controls if empty XML elements should be collapsed into a self closing element or expanded",
     )
+    format_group.add_argument(
+        "-N",
+        "--add-eof-newline",
+        action="store_true",
+        help="controls if a trailing newline is appended to the output",
+    )
 
     msg = "XML (XSD) file(s) to format, use '-' to read from stdin"
     parser.add_argument("inputs", nargs="+", type=_path_creator, help=msg)
@@ -133,11 +140,14 @@ def _handle_one(filename: Path | None, opts: Options) -> bool:
 def _format(raw: str, opts: Options) -> str:
     element = XML(raw)
     indent(element, opts.indent)
-    return tostring(
-        element,
-        encoding="unicode",
-        xml_declaration=True,
-        short_empty_elements=not opts.expand_empty_elements,
+    return (
+        tostring(
+            element,
+            encoding="unicode",
+            xml_declaration=True,
+            short_empty_elements=not opts.expand_empty_elements,
+        )
+        + "\n" * opts.add_eof_newline
     )
 
 

tests/test_main.py

@@ -128,3 +128,17 @@ def test_xml_path_no_write(capsys: pytest.CaptureFixture[str], min_xml: Path) ->
     out, err = capsys.readouterr()
     assert "\nxml-fmt: error: argument inputs: cannot write path\n" in err
     assert not out
+
+
+def test_xml_format_add_newline(capsys: pytest.CaptureFixture[str], tmp_path: Path, min_xml_str: str) -> None:
+    xml = tmp_path / "name.xml"
+    xml.write_text(min_xml_str)
+
+    exit_code = run([str(xml), "--no-print-diff", "--add-eof-newline"])
+
+    assert xml.read_text() == min_xml_str + "\n"
+    assert exit_code == 1
+
+    out, err = capsys.readouterr()
+    assert not err
+    assert out.splitlines() == []