Initial commit after splitting from main project

tests/TapTest.php

@@ -0,0 +1,62 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tez\Utils\Tests\Fn;
+
+use PHPUnit\Framework\TestCase;
+use Tez\Utils\Fn\Tap;
+
+final class TapTest extends TestCase
+{
+    public function testReturnsOriginalValue(): void
+    {
+        $result = Tap::value('hello', fn($v) => strtoupper($v));
+
+        self::assertSame('hello', $result);
+    }
+
+    public function testCallableSideEffectIsExecuted(): void
+    {
+        $called = false;
+
+        Tap::value('anything', function () use (&$called): void {
+            $called = true;
+        });
+
+        self::assertTrue($called);
+    }
+
+    public function testCallableReceivesTheValue(): void
+    {
+        $received = null;
+
+        Tap::value(42, function (int $v) use (&$received): void {
+            $received = $v;
+        });
+
+        self::assertSame(42, $received);
+    }
+
+    public function testReturnValueOfCallableIsDiscarded(): void
+    {
+        $result = Tap::value('original', fn() => 'ignored');
+
+        self::assertSame('original', $result);
+    }
+
+    public function testWorksWithObjects(): void
+    {
+        $obj    = new \stdClass();
+        $result = Tap::value($obj, fn($v) => null);
+
+        self::assertSame($obj, $result);
+    }
+
+    public function testWorksWithNull(): void
+    {
+        $result = Tap::value(null, fn($v) => 'ignored');
+
+        self::assertNull($result);
+    }
+}