test only

Author: brenoroosevelt

composer.json

@@ -43,6 +43,7 @@
             "src/IndexOf.php",
             "src/Map.php",
             "src/None.php",
+            "src/Only.php",
             "src/Pipe.php",
             "src/Pull.php",
             "src/Pull.php",

src/Only.php

@@ -0,0 +1,17 @@
+<?php
+declare(strict_types=1);
+
+namespace BrenoRoosevelt;
+
+/**
+ * Returns a subset of the collection with elements that match given keys.
+ * The keys are preserved
+ *
+ * @param array $items The collection
+ * @param mixed ...$keys keys to be filtered
+ * @return array
+ */
+function only(array $items, ...$keys): array
+{
+    return array_intersect_key($items, array_flip($keys));
+}

src/array_functions.php

@@ -3,11 +3,6 @@
 
 namespace BrenoRoosevelt;
 
-function only(array $items, ...$keys): array
-{
-    return array_intersect_key($items, array_flip($keys));
-}
-
 function except(array $items, ...$keys): array
 {
     return array_diff_key($items, array_flip($keys));

tests/OnlyTest.php

@@ -0,0 +1,35 @@
+<?php
+declare(strict_types=1);
+
+namespace BrenoRoosevelt\Tests;
+
+use PHPUnit\Framework\TestCase;
+use function BrenoRoosevelt\only;
+use function BrenoRoosevelt\reject;
+
+class OnlyTest extends TestCase
+{
+    public function testOnly()
+    {
+        $elements = [1, 'b', 'c', 'd'];
+        $this->assertEquals([1, 'b'], only($elements, 0, 1));
+    }
+
+    public function testOnlyPreserveKeys()
+    {
+        $elements = [1, 'b', 'c', 'd'];
+        $this->assertEquals([2 => 'c'], only($elements, 2));
+    }
+
+    public function testOnlyKeyNotExists()
+    {
+        $elements = [1, 'b', 'c', 'd'];
+        $this->assertEquals([], only($elements, 'b'));
+    }
+
+    public function testOnlyKeyPreserveValues()
+    {
+        $elements = [1, 'c' => [[[2]]]];
+        $this->assertEquals(['c' => [[[2]]]], only($elements, 'c'));
+    }
+}