test: cover --list-sheets error cases

Author: Arturo R Montesinos

tests/test_cli.py

@@ -46,3 +46,20 @@ def test_list_sheets_prints_sheet_names_and_exits_zero() -> None:
     # should be at least one non-empty line of output.
     lines = [line.strip() for line in result.stdout.splitlines() if line.strip()]
     assert lines
+
+
+def test_list_sheets_without_file_is_usage_error() -> None:
+    result = run_cli("--list-sheets")
+    assert result.returncode == 2
+    assert "--list-sheets requires a FILE argument" in result.stderr
+
+
+def test_list_sheets_with_missing_file_is_runtime_error() -> None:
+    project_root = Path(__file__).resolve().parents[1]
+    missing = project_root / "tests" / "fixtures" / "does-not-exist.ods"
+    assert not missing.exists()
+
+    result = run_cli("--list-sheets", str(missing))
+    assert result.returncode == 1
+    # Error message should mention the missing file path.
+    assert str(missing) in result.stderr