fix(formatter): leave empty lines in descriptions

src/ops2deb/formatter.py

@@ -28,8 +28,9 @@ def sort_blueprints(blueprints: List[Blueprint]) -> List[Blueprint]:
 
 def format_description(description: str) -> str:
     lines: List[str] = []
+    description = description.strip("\n")
     for line in description.split("\n"):
-        lines.extend(wrap(line, width=79))
+        lines.extend(wrap(line, width=79) or [""])
     return "\n".join(lines)
 
 

tests/test_formatter.py

@@ -1,6 +1,8 @@
+import pytest
+
 from ops2deb.formatter import format_description
 
-description_with_empty_line = """\
+description_with_empty_line = """
 This thing does the following:
 
 - It does this
@@ -12,13 +14,18 @@
 """
 
 
-def test_format_description_should_remove_empty_lines():
+def test_format_description_should_only_remove_empty_lines_at_start_or_end():
     result = format_description(description_with_empty_line)
-    assert "" not in result.split("\n")
+    assert result[0] != "\n"
+    assert result[-1] != "\n"
+    assert "\n" in result
 
 
-def test_format_description_should_be_idempotent():
-    result = format_description(description_with_empty_line)
+@pytest.mark.parametrize(
+    "description", [description_with_empty_line, description_with_long_line]
+)
+def test_format_description_should_be_idempotent(description):
+    result = format_description(description)
     assert format_description(result) == result