chore: implement basic tests

Signed-off-by: Sebastian Krupinski <krupinski01@gmail.com>

tests/php/BaseTest.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace KTXT;
+
+use PHPUnit\Framework\TestCase;
+
+class BaseTest extends TestCase
+{
+    public function testBasicAssertion(): void
+    {
+        $this->assertTrue(true);
+    }
+
+    public function testArrayOperations(): void
+    {
+        $array = ['foo' => 'bar'];
+        
+        $this->assertArrayHasKey('foo', $array);
+        $this->assertEquals('bar', $array['foo']);
+    }
+
+    public function testStringOperations(): void
+    {
+        $string = 'Hello, World!';
+        
+        $this->assertStringContainsString('World', $string);
+        $this->assertEquals(13, strlen($string));
+    }
+}