Introduce registerUndefinedTestCallback

Author: VincentLanglet

src/Environment.php

@@ -827,6 +827,14 @@ public function getTest(string $name): ?TwigTest
         return $this->extensionSet->getTest($name);
     }
 
+    /**
+     * @param callable(string): (TokenParserInterface|false) $callable
+     */
+    public function registerUndefinedTestCallback(callable $callable): void
+    {
+        $this->extensionSet->registerUndefinedTestCallback($callable);
+    }
+
     /**
      * @return void
      */

src/ExtensionSet.php

@@ -59,6 +59,8 @@ final class ExtensionSet
     private $functionCallbacks = [];
     /** @var array<callable(string): (TwigFilter|false)> */
     private $filterCallbacks = [];
+    /** @var array<callable(string): (TwigTest|false)> */
+    private $testCallbacks = [];
     /** @var array<callable(string): (TokenParserInterface|false)> */
     private $parserCallbacks = [];
     private $lastModified = 0;
@@ -410,9 +412,23 @@ public function getTest(string $name): ?TwigTest
             }
         }
 
+        foreach ($this->testCallbacks as $callback) {
+            if (false !== $test = $callback($name)) {
+                return $test;
+            }
+        }
+
         return null;
     }
 
+    /**
+     * @param callable(string): (TwigTest|false) $callable
+     */
+    public function registerUndefinedTestCallback(callable $callable): void
+    {
+        $this->testCallbacks[] = $callable;
+    }
+
     public function getExpressionParsers(): ExpressionParsers
     {
         if (!$this->initialized) {

tests/EnvironmentTest.php

@@ -425,6 +425,22 @@ public function testUndefinedFilterCallback()
         $this->assertSame('dynamic', $filter->getName());
     }
 
+    public function testUndefinedTestCallback()
+    {
+        $twig = new Environment(new ArrayLoader());
+        $twig->registerUndefinedTestCallback(function (string $name) {
+            if ('dynamic' === $name) {
+                return new TwigTest('dynamic', function () { return 'dynamic'; });
+            }
+
+            return false;
+        });
+
+        $this->assertNull($twig->getTest('does_not_exist'));
+        $this->assertInstanceOf(TwigTest::class, $test = $twig->getTest('dynamic'));
+        $this->assertSame('dynamic', $test->getName());
+    }
+
     public function testUndefinedTokenParserCallback()
     {
         $twig = new Environment(new ArrayLoader());