Add template for getRuntime method (#164)

.editorconfig

@@ -0,0 +1,10 @@
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+indent_style = space
+indent_size = 2
+
+[{*.php, *.json}]
+indent_size = 4

src/Stubs/common/TwigEnvironment.stubphp

@@ -11,4 +11,15 @@ class Environment
      * @psalm-taint-specialize
      */
     public function render($name, array $context = []): string {}
+
+    /**
+     * @template T of object
+     *
+     * @param class-string<T> $class
+     *
+     * @return T
+     *
+     * @throws RuntimeError When the template cannot be found
+     */
+    public function getRuntime($class) {}
 }

tests/acceptance/acceptance/TwigEnvironment.feature

@@ -0,0 +1,37 @@
+@symfony-common
+Feature: Twig Environment
+
+  Background:
+    Given I have the following config
+      """
+      <?xml version="1.0"?>
+      <psalm errorLevel="1">
+        <projectFiles>
+          <directory name="."/>
+          <ignoreFiles> <directory name="../../vendor"/> </ignoreFiles>
+        </projectFiles>
+
+        <plugins>
+          <pluginClass class="Psalm\SymfonyPsalmPlugin\Plugin"/>
+        </plugins>
+      </psalm>
+      """
+
+  Scenario: getRuntime method return type is dynamic
+    Given I have the following code
+    """
+    <?php
+
+    use Symfony\Component\Form\FormRenderer;
+    use Twig\Environment;
+
+    class Foo
+    {
+    public function foo(Environment $environment): FormRenderer
+    {
+      return $environment->getRuntime(FormRenderer::class);
+    }
+    }
+    """
+    When I run Psalm
+    Then I see no errors