Fix Markup truthiness in boolean expressions

[xtrime-ru]

Summary

Fixes Markup truthiness handling in boolean expressions.

trim can return a Twig\Markup instance for safe strings. Empty Markup objects must behave like empty strings in Twig truth tests, but PHP treats all objects as truthy. This caused expressions like this to incorrectly evaluate as true:

{% set x %}    {% endset %}
{% if x|trim and x|trim %}fail{% else %}ok{% endif %}

This case was working properly in https://github.com/twigphp/Twig/releases/tag/v3.14.2 and earlier.

Related commits

• Bug was introduced in v3.15.0 in this commit 10c3142
• Partially fixed here: 10c3142

Changes

• Added TrueTest::wrap() to centralize wrapping non-primitive expressions with Twig’s Markup-aware true test.
• Reused TrueTest::wrap() in:
  • IfNode
  • conditional ternary expressions
  • and, or, and xor binary expressions
  • Elvis expressions
  • unary not
• Added regression coverage for boolean operators (and, or, xor, not) and ternary/Elvis expressions whose operands evaluate to empty Markup.

Tests

./vendor/bin/simple-phpunit tests/IntegrationTest.php --filter markup_test

[fabpot]

Thank you @xtrime-ru.