Add more tests

Author: JBlond

tests/Diff/Renderer/Html/MergedTest.php

@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Diff\Renderer\Html;
+
+use jblond\Diff;
+use jblond\Diff\Renderer\Html\Merged;
+use PHPUnit\Framework\TestCase;
+
+class MergedTest extends TestCase
+{
+    public function testMergedRendererReplaceCase()
+    {
+        $a = "line1\nsame\nline3";
+        $b = "line1\nchanged\nline3";
+
+        $diff = new Diff($a, $b);
+        $output = $diff->render(new Merged());
+
+        $this->assertStringContainsString('<del', $output);
+        $this->assertStringContainsString('<ins', $output);
+    }
+}