Add cases

Test/Integration/AbstractTestCase.php

@@ -0,0 +1,16 @@
+<?php declare(strict_types=1);
+
+namespace Yireo\LinkPreload\Test\Integration;
+
+use Magento\Framework\App\Config\ScopeConfigInterface;
+use Magento\TestFramework\TestCase\AbstractController;
+
+class AbstractTestCase extends AbstractController
+{
+    protected function assertEnabledValue(int $expectedValue): void
+    {
+        /** @var ScopeConfigInterface $scopeConfig */
+        $scopeConfig = $this->_objectManager->get(ScopeConfigInterface::class);
+        $this->assertEquals($expectedValue, $scopeConfig->getValue('system/yireo_linkpreload/enabled'));
+    }
+}

Test/Integration/BodyTest.php

@@ -0,0 +1,55 @@
+<?php declare(strict_types=1);
+
+namespace Yireo\LinkPreload\Test\Integration;
+
+class BodyTest extends AbstractTestCase
+{
+    /**
+     * @magentoAdminConfigFixture system/yireo_linkpreload/enabled 1
+     */
+    public function testIfLinkHeadersExistsWhenModuleIsEnabled()
+    {
+        $this->assertEnabledValue(1);
+        $this->dispatch('/');
+        $body = (string)$this->getResponse()->getBody();
+        foreach ((new LinkDataProvider())->getLinks() as $link) {
+            $this->assertBodyContainsLink($link[0], $link[1], $body);
+        }
+    }
+
+    /**
+     * @magentoAdminConfigFixture system/yireo_linkpreload/enabled 1
+     * @magentoCache full_page enabled
+     * @magentoDbIsolation enabled
+     * @magentoAppIsolation enabled
+     */
+    public function testIfLinkHeadersExistsWhenModuleIsEnabledAndWithFullPageCache()
+    {
+        if (constant('TESTS_CLEANUP') === 'disabled') {
+            $this->markTestSkipped('Test does not work with TESTS_CLEANUP disabled');
+        }
+
+        $this->assertEnabledValue(1);
+        $this->dispatch('/');
+        $body = (string)$this->getResponse()->getBody();
+        $this->assertNotEmpty($body);
+
+        foreach ((new LinkDataProvider())->getLinks() as $link) {
+            $this->assertBodyContainsLink($link[0], $link[1], $body);
+        }
+    }
+
+    private function assertBodyContainsLink(string $type, string $uri, string $body)
+    {
+        preg_match_all('#<link(.*)rel="preload"(.*)>#', $body, $matches);
+
+        $foundUri = false;
+        foreach ($matches[0] as $match) {
+            if (strstr($match, $uri)) {
+                $foundUri = true;
+            }
+        }
+
+        $this->assertTrue($foundUri, 'URI "'.$uri.'" not found in body: '.$body);
+    }
+}

Test/Integration/LinkDataProvider.php

@@ -0,0 +1,19 @@
+<?php declare(strict_types=1);
+
+namespace Yireo\LinkPreload\Test\Integration;
+
+class LinkDataProvider
+{
+    public function getLinks(): array
+    {
+        return [
+            ['style', 'css/styles-l.css'],
+            ['style', 'css/styles-m.css'],
+            ['style', 'css/print.css'],
+            ['style', 'mage/calendar.css'],
+            ['script', 'requirejs/require.js'],
+            ['script', 'jquery.js'],
+            ['script', 'mage/bootstrap.js'],
+        ];
+    }
+}

etc/frontend/di.xml

@@ -5,10 +5,4 @@
     <type name="Magento\Framework\App\ResponseInterface">
         <plugin name="linkpreload-response" type="Yireo\LinkPreload\Plugin\ResponsePlugin" sortOrder="99"/>
     </type>
-
-    <!--
-    <type name="Magento\Framework\View\Result\Layout">
-        <plugin name="linkpreload-result" type="Yireo\LinkPreload\Plugin\LayoutPlugin" sortOrder="99"/>
-    </type>
-    -->
 </config>