Add addLast() function

tests/Functions/LastFunctionTest.php

@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Functions;
+
+use Arendsen\FluxQueryBuilder\Functions\Last;
+use PHPUnit\Framework\TestCase;
+
+final class LastFunctionTest extends TestCase
+{
+	public function testSimpleLast()
+	{
+		$expression = new Last();
+
+		$query = '|> last(column: "_value") ';
+
+		$this->assertEquals($query, $expression->__toString());
+	}
+
+	public function testLastWithValue()
+	{
+		$expression = new Last('something');
+
+		$query = '|> last(column: "something") ';
+
+		$this->assertEquals($query, $expression->__toString());
+	}
+}