[11.x] Add multiply to collection (laravel#51870)

* Add multiply to collection

Multiply the items in the collection by the multiplier.

* Update Collection.php

* Update LazyCollection.php

---------

Co-authored-by: Taylor Otwell <taylor@laravel.com>

src/Illuminate/Collections/Collection.php

@@ -831,6 +831,23 @@ public function mergeRecursive($items)
         return new static(array_merge_recursive($this->items, $this->getArrayableItems($items)));
     }
 
+    /**
+     * Multiply the items in the collection by the multiplier.
+     *
+     * @param  int  $multiplier
+     * @return static
+     */
+    public function multiply(int $multiplier)
+    {
+        $new = new static;
+
+        for ($i = 0; $i < $multiplier; $i++) {
+            $new->push(...$this->items);
+        }
+
+        return $new;
+    }
+
     /**
      * Create a collection by using this collection for keys and another for its values.
      *

src/Illuminate/Collections/LazyCollection.php

@@ -841,6 +841,17 @@ public function mergeRecursive($items)
         return $this->passthru('mergeRecursive', func_get_args());
     }
 
+    /**
+     * Multiply the items in the collection by the multiplier.
+     *
+     * @param  int  $multiplier
+     * @return static
+     */
+    public function multiply(int $multiplier)
+    {
+        return $this->passthru('multiply', func_get_args());
+    }
+
     /**
      * Create a collection by using this collection for keys and another for its values.
      *

tests/Database/DatabaseEloquentCollectionTest.php

@@ -510,6 +510,21 @@ public function testMakeVisibleRemovesHiddenAndIncludesVisible()
         $this->assertEquals(['visible', 'hidden'], $c[0]->getVisible());
     }
 
+    public function testMultiply()
+    {
+        $a = new TestEloquentCollectionModel();
+        $b = new TestEloquentCollectionModel();
+
+        $c = new Collection([$a, $b]);
+
+        $this->assertEquals([], $c->multiply(-1)->all());
+        $this->assertEquals([], $c->multiply(0)->all());
+
+        $this->assertEquals([$a, $b], $c->multiply(1)->all());
+
+        $this->assertEquals([$a, $b, $a, $b, $a, $b], $c->multiply(3)->all());
+    }
+
     public function testQueueableCollectionImplementation()
     {
         $c = new Collection([new TestEloquentCollectionModel, new TestEloquentCollectionModel]);

tests/Support/SupportCollectionTest.php

@@ -1259,6 +1259,25 @@ public function testMergeRecursiveCollection($collection)
         );
     }
 
+    #[DataProvider('collectionClassProvider')]
+    public function testMultiplyCollection($collection)
+    {
+        $c = new $collection(['Hello', 1, ['tags' => ['a', 'b'], 'admin']]);
+
+        $this->assertEquals([], $c->multiply(-1)->all());
+        $this->assertEquals([], $c->multiply(0)->all());
+
+        $this->assertEquals(
+            ['Hello', 1, ['tags' => ['a', 'b'], 'admin']],
+            $c->multiply(1)->all()
+        );
+
+        $this->assertEquals(
+            ['Hello', 1, ['tags' => ['a', 'b'], 'admin'], 'Hello', 1, ['tags' => ['a', 'b'], 'admin'], 'Hello', 1, ['tags' => ['a', 'b'], 'admin']],
+            $c->multiply(3)->all()
+        );
+    }
+
     #[DataProvider('collectionClassProvider')]
     public function testReplaceNull($collection)
     {