feat: add unit tests

t/10-html-escape.t

@@ -0,0 +1,30 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+
+use Test::More tests => 4;
+use MarkdownParser;
+
+my $parser = MarkdownParser->new();
+
+is(
+    $parser->parse("Text with <tag>"),
+    "<p>Text with &lt;tag&gt;</p>\n",
+    "HTML tags escaped"
+);
+is(
+    $parser->parse("Text with & symbol"),
+    "<p>Text with &amp; symbol</p>\n",
+    "Ampersand escaped"
+);
+is(
+    $parser->parse('Text with "quotes"'),
+    "<p>Text with &quot;quotes&quot;</p>\n",
+    "Quotes escaped"
+);
+is(
+    $parser->parse("Text with 'apostrophe'"),
+    "<p>Text with &#39;apostrophe&#39;</p>\n",
+    "Apostrophe escaped"
+);
+