Issue #2417733 by joelpittet, martin107: Drupal 8 breaks Twig's round filter

core/tests/Drupal/Tests/Core/Theme/TwigEngineTest.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\Core\Theme\TwigEngineTest.
+ */
+
+namespace Drupal\Tests\Core\Theme;
+
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * Test coverage for the file core/themes/engines/twig/twig.engine.
+ *
+ * @group Theme
+ */
+class TwigEngineTest extends UnitTestCase {
+
+  /**
+   * The mocked Twig environment.
+   *
+   * @var \Twig_Environment|\PHPUnit_Framework_MockObject_MockObject
+   */
+  protected $twigEnvironment;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    // Ensure that twig.engine is loaded, it is needed to access
+    // twig_drupal_escape_filter().
+    require_once $this->root . '/core/themes/engines/twig/twig.engine';
+
+    $this->twigEnvironment = $this->getMock('\Twig_Environment');
+  }
+
+  /**
+   * Tests output of integer and double 0 values of twig_render_var().
+   *
+   * @see https://www.drupal.org/node/2417733
+   */
+  public function testsRenderZeroValue() {
+    $this->assertSame(twig_render_var(0), 0, 'twig_render_var() renders zero correctly when provided as an integer.');
+    $this->assertSame(twig_render_var(0.0), 0, 'twig_render_var() renders zero correctly when provided as a double.');
+  }
+
+  /**
+   * Tests output of integer and double 0 values of twig_drupal_escape_filter().
+   *
+   * @see https://www.drupal.org/node/2417733
+   */
+  public function testsRenderEscapedZeroValue() {
+    $this->assertSame(twig_drupal_escape_filter($this->twigEnvironment, 0), 0, 'twig_escape_filter() returns zero correctly when provided as an integer.');
+    $this->assertSame(twig_drupal_escape_filter($this->twigEnvironment, 0.0), 0, 'twig_escape_filter() returns zero correctly when provided as a double.');
+  }
+
+}

core/themes/engines/twig/twig.engine

@@ -127,8 +127,8 @@ function twig_render_template($template_file, array $variables) {
  * @see TwigNodeVisitor
  */
 function twig_render_var($arg) {
-  // Check for numeric zero.
-  if ($arg === 0) {
+  // Check for a numeric zero int or float.
+  if ($arg === 0 || $arg === 0.0) {
     return 0;
   }
 
@@ -213,8 +213,8 @@ function twig_without($element) {
  *   The escaped, rendered output, or NULL if there is no valid output.
  */
 function twig_drupal_escape_filter(\Twig_Environment $env, $string, $strategy = 'html', $charset = NULL, $autoescape = FALSE) {
-  // Check for a numeric zero.
-  if ($string === 0) {
+  // Check for a numeric zero int or float.
+  if ($string === 0 || $string === 0.0) {
     return 0;
   }