Added asResource() method

README.md

@@ -67,6 +67,7 @@ composer require std-library/type-guard
 - [`asCallable()`](#ascallable)
 - [`not()->null()`](#notnull)
 - [`asArray()`](#asarray)
+- [`asResource()`](#asresource)
 
 ### `as`
 
@@ -140,6 +141,14 @@ Asserts and narrows down the type of the given variable to an array.
 $variable = type($variable)->asArray();
 ```
 
+### `asResource()`
+
+Asserts and narrows down the type of the given variable to a resource.
+
+```php
+$variable = type($variable)->asResource();
+```
+
 ------
 
 **Type Guard** is part of the [PHP's Standard Library](https://github.com/std-library) project. It was created by **[Nuno Maduro](https://twitter.com/enunomaduro)** and open-sourced under the **[MIT license](https://opensource.org/licenses/MIT)**.

src/Type.php

@@ -129,6 +129,22 @@ public function asArray(): array
         return $this->variable;
     }
 
+    /**
+     * Asserts and narrow down the type to a resource.
+     *
+     * @phpstan-assert-if-true resource $this->variable
+     *
+     * @return resource
+     */
+    public function asResource(): mixed
+    {
+        if (! is_resource($this->variable)) {
+            throw new TypeError('Variable is not a [resource].');
+        }
+
+        return $this->variable;
+    }
+
     /**
      * Asserts and narrow down the type to a callable.
      *

tests/AsResourceTest.php

@@ -0,0 +1,19 @@
+<?php
+
+declare(strict_types=1);
+
+test('resource type', function (): void {
+    $variable = fopen('php://memory', 'r');
+
+    $value = type($variable)->asResource();
+
+    expect($value)->toBeResource();
+
+    fclose($variable);
+});
+
+test('not resource', function (): void {
+    $variable = [];
+
+    type($variable)->asResource();
+})->throws(TypeError::class, 'Variable is not a [resource].');

types/AsResourceTest.php

@@ -0,0 +1,10 @@
+<?php
+
+declare(strict_types=1);
+
+use function PHPStan\Testing\assertType;
+
+$resource = fopen('php://memory', 'r');
+$variable = random_int(0, 1) !== 0 ? 'string' : $resource;
+assertType('resource', $variable = type($variable)->asResource());
+fclose($variable);