Includes: Started foundations for new include tag parser

tests/Unit/PageIncludeParserTest.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace Tests\Unit;
+
+use BookStack\Entities\Tools\PageIncludeParser;
+use Tests\TestCase;
+
+class PageIncludeParserTest extends TestCase
+{
+    public function test_include_simple_inline_text()
+    {
+        $this->runParserTest(
+            '<p>{{@45#content}}</p>',
+            ['45' => '<p id="content">Testing</p>'],
+            '<p>Testing</p>',
+        );
+    }
+
+    public function test_include_simple_inline_text_with_existing_siblings()
+    {
+        $this->runParserTest(
+            '<p>{{@45#content}} <strong>Hi</strong>there!</p>',
+            ['45' => '<p id="content">Testing</p>'],
+            '<p>Testing <strong>Hi</strong>there!</p>',
+        );
+    }
+
+    public function test_include_simple_inline_text_within_other_text()
+    {
+        $this->runParserTest(
+            '<p>Hello {{@45#content}}there!</p>',
+            ['45' => '<p id="content">Testing</p>'],
+            '<p>Hello Testingthere!</p>',
+        );
+    }
+
+    protected function runParserTest(string $html, array $contentById, string $expected)
+    {
+        $parser = new PageIncludeParser($html, function (int $id) use ($contentById) {
+            return $contentById[strval($id)] ?? null;
+        });
+
+        $result = $parser->parse();
+        $this->assertEquals($expected, $result);
+    }
+}