test sum

Author: brenoroosevelt

composer.json

@@ -54,7 +54,7 @@
             "src/RemoveKey.php",
             "src/Set.php",
             "src/Some.php",
-            "src/array_functions.php"
+            "src/Sum.php"
         ]
     },
     "autoload-dev": {

src/Sum.php

@@ -0,0 +1,36 @@
+<?php
+declare(strict_types=1);
+
+namespace BrenoRoosevelt;
+
+/**
+ * Sums the values returned by the callabck function for each element in the collection
+ *
+ * @param iterable $items The collection
+ * @param callable $callback The callable that must return int or float value
+ * @param int $mode [optional] <p>
+ * Flag determining what arguments are sent to <i>callback</i>:
+ * </p><ul>
+ * <li>
+ * <b>CALLBACK_USE_VALUE</b> - <b>default</b> pass value as the only argument
+ * </li>
+ * <li>
+ * <b>CALLBACK_USE_KEY</b> - pass key as the only argument
+ * to <i>callback</i> instead of the value</span>
+ * </li>
+ * <li>
+ * <b>CALLBACK_USE_BOTH</b> - pass both value and key as
+ * arguments to <i>callback</i></span>
+ * </li>
+ * </ul>
+ * @return array
+ */
+function sum(iterable $items, callable $callback, int $mode = 0)
+{
+    $sum = 0;
+    foreach ($items as $key => $value) {
+        $sum += call_user_func_array($callback, __args($mode, $key, $value));
+    }
+
+    return $sum;
+}

src/array_functions.php

@@ -0,0 +1,36 @@
+<?php
+declare(strict_types=1);
+
+namespace BrenoRoosevelt\Tests;
+
+use PHPUnit\Framework\TestCase;
+use function BrenoRoosevelt\sum;
+use const BrenoRoosevelt\CALLBACK_USE_BOTH;
+use const BrenoRoosevelt\CALLBACK_USE_KEY;
+
+class SumTest extends TestCase
+{
+    public function testSum()
+    {
+        $elements = [1, 2, 3];
+        $this->assertEquals(15, sum($elements, fn($v) => 5));
+    }
+
+    public function testSumValues()
+    {
+        $elements = [1, 2, 3];
+        $this->assertEquals(6, sum($elements, fn($v) => $v));
+    }
+
+    public function testSumKeys()
+    {
+        $elements = [1, 2, 3];
+        $this->assertEquals(3, sum($elements, fn($k) => $k, CALLBACK_USE_KEY));
+    }
+
+    public function testSumBoth()
+    {
+        $elements = [1, 2, 3];
+        $this->assertEquals(9, sum($elements, fn($v, $k) => $k + $v, CALLBACK_USE_BOTH));
+    }
+}