Add a handy CallbackReader to read from Closure (#119)

* Add a handy CallbackReader to read from Closure

* Add class comment to CallbackReader

Author: yann-eugone

src/batch/docs/domain/item-job/item-reader.md

@@ -21,6 +21,8 @@ It can be any class implementing [ItemReaderInterface](../../../src/Job/Item/Ite
   read from multiple item reader, one after the other.
 - [StaticIterableReader](../../../src/Job/Item/Reader/StaticIterableReader.php):
   read from an iterable you provide during construction.
+- [CallbackReader](../../../src/Job/Item/Reader/CallbackReader.php):
+  read from a `Closure` you provide during construction.
 
 **Item readers from bridges:**
 - [FlatFileReader (`openspout/openspout`)](https://github.com/yokai-php/batch-openspout/blob/0.x/src/Reader/FlatFileReader.php):

src/batch/src/Job/Item/Reader/CallbackReader.php

@@ -0,0 +1,28 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Yokai\Batch\Job\Item\Reader;
+
+use Yokai\Batch\Job\Item\ItemReaderInterface;
+
+/**
+ * An {@see ItemReaderInterface} that read from a {@see Closure} provided at construction.
+ *
+ * Provided {@see Closure} must accept no argument and must return an iterable of read items.
+ */
+final class CallbackReader implements ItemReaderInterface
+{
+    public function __construct(
+        /**
+         * @var \Closure(): iterable<mixed>
+         */
+        private readonly \Closure $callback,
+    ) {
+    }
+
+    public function read(): iterable
+    {
+        return ($this->callback)();
+    }
+}

src/batch/tests/Job/Item/Reader/CallbackReaderTest.php

@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Yokai\Batch\Tests\Job\Item\Reader;
+
+use PHPUnit\Framework\TestCase;
+use Yokai\Batch\Job\Item\Reader\CallbackReader;
+
+class CallbackReaderTest extends TestCase
+{
+    /**
+     * @dataProvider provider
+     */
+    public function test(array $expected, \Closure $closure): void
+    {
+        $items = [];
+        foreach ((new CallbackReader($closure))->read() as $item) {
+            $items[] = $item;
+        }
+
+        self::assertSame($expected, $items);
+    }
+
+    public static function provider(): \Generator
+    {
+        yield 'array' => [
+            [1, 2, 3],
+            fn() => [1, 2, 3],
+        ];
+        yield 'iterator' => [
+            [1, 2, 3],
+            fn() => new \ArrayIterator([1, 2, 3]),
+        ];
+        yield 'generator' => [
+            [1, 2, 3],
+            function () {
+                yield 1;
+                yield 2;
+                yield 3;
+            },
+        ];
+    }
+}