code: def test_string_literal_var(env):
      t = env.from_string("[{{ 'all' }}]")
      result = t.render()
      assert isinstance(result, str)
      assert result == "[all]"
  
imports: import math
  import pytest
  from jinja2.exceptions import UndefinedError
  from jinja2.nativetypes import NativeEnvironment
  from jinja2.nativetypes import NativeTemplate
  from jinja2.runtime import Undefined
label_desc: Use image node_id 15 for calling a global function with example usage: test_string_literal_var(env) without return types