add the reduce() method which is a wrapper of the native array_reduce…

…() method.

src/ArrayUtils.php

@@ -94,4 +94,17 @@ public function search(string $searchParam)
     {
         return array_search($searchParam, $this->collection);
     }
+
+    /**
+     * Wrapper method for array_reduce
+     *
+     * @param Closure $callback
+     * @param mixed $initial
+     * 
+     * @return mixed
+     */
+    public function reduce(Closure $callback, $initial = null)
+    {
+        return array_reduce($this->collection, $callback, $initial);
+    }
 }

tests/ArrayUtilsTest.php

@@ -45,4 +45,26 @@ public function it_successfully_gets_array_values()
 
         $this->assertEquals(['Peter', '41', 'USA'], ArrayUtils::getInstance()->collect($user)->getValues());
     }
+
+    /** @test */
+    public function it_successfully_reduces_array()
+    {
+        $this->assertEquals(15, ArrayUtils::getInstance()
+            ->collect([1, 2, 3, 4, 5])
+            ->reduce(function($carry, $item) {
+                $carry += $item;
+                return $carry;
+            }));
+    }
+
+    /** @test */
+    public function it_successfully_reduces_array_with_initial_value()
+    {
+        $this->assertEquals(1200, ArrayUtils::getInstance()
+            ->collect([1, 2, 3, 4, 5])
+            ->reduce(function($carry, $item) {
+                $carry *= $item;
+                return $carry;
+            }, 10));
+    }
 }