fix: add newline indentation after existing items in Container class (#421)

Fix #387

Signed-off-by: Frost Ming <[email protected]>

Author: frostming

CHANGELOG.md

@@ -9,6 +9,7 @@
 ### Fixed
 
 - Fix non-existing key error when deleting an item from an out-of-order table. ([#383](https://github.com/python-poetry/tomlkit/issues/383))
+- Ensure newline is added between the plain values and the first table. ([#387](https://github.com/python-poetry/tomlkit/issues/387))
 - Fix repeated whitespace when removing an array item. ([#405](https://github.com/python-poetry/tomlkit/issues/405))
 - Fix invalid serialization after removing array item if the comma is on its own line. ([#408](https://github.com/python-poetry/tomlkit/issues/408))
 - Fix serialization of a nested dotted key table. ([#411](https://github.com/python-poetry/tomlkit/issues/411))

tests/test_toml_document.py

@@ -692,6 +692,7 @@ def test_update_nested_out_of_order_table():
         == """\
 [root1.root2.a]
 tmp = "hi"
+
 [root1.root2.a.b.c]
   value = 2
 [WALRUS]
@@ -814,6 +815,7 @@ def test_replace_table_with_value():
     assert (
         doc.as_string()
         == """bar = 42
+
 [foo]
 a = 1
 

tomlkit/container.py

@@ -289,6 +289,12 @@ def append(
             last_index = self._get_last_index_before_table()
 
             if last_index < len(self._body):
+                after_item = self._body[last_index][1]
+                if not (
+                    isinstance(after_item, Whitespace)
+                    or "\n" in after_item.trivia.indent
+                ):
+                    after_item.trivia.indent = "\n" + after_item.trivia.indent
                 return self._insert_at(last_index, key, item)
             else:
                 previous_item = self._body[-1][1]