Test array literal serialization

docs/migration.md

@@ -44,6 +44,7 @@ The following features are new or are now built-in where they weren't before.
 
 These features are not yet included in Python Liquid2, but can be if there is a demand.
 
+- We no longer offer a "lax" or "warn" parsing mode, previously controlled by the `tolerance` argument to `Environment`. The assertion is that errors should be loud and we should be made aware as early as possible, whether you're an experienced developer or not.
 - Async filters have not been implemented.
 - Contextual template analysis has not been implemented.
 - Template tag analysis (analyzing tokens instead of a syntax tree) has not been implemented.

tests/test_template_str.py

@@ -436,3 +436,9 @@ def test_template_string_str() -> None:
     source = "{{ 'Hello' if not you else 'Hello there, ${you}!' }}"
     template = parse(source)
     assert str(template) == source
+
+
+def test_array_literal_str() -> None:
+    source = "{% assign my_array = 1, 2, 3 %}"
+    template = parse(source)
+    assert str(template) == source