Add initial test

tests/Unit/inc/Engine/Media/Fonts/Controller/Filesystem/writeFontCss.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace WP_Rocket\Tests\Unit\inc\Engine\Media\Fonts\Controller\Filesystem;
+
+
+use Brain\Monkey\Functions;
+use WP_Rocket\Engine\Media\Fonts\Controller\Filesystem;
+use WP_Rocket\Tests\Unit\FilesystemTestCase;
+
+/**
+ * Test class covering \WP_Rocket\Engine\Media\Fonts\Controller\Filesystem::write_font_css
+ *
+ * @group FontOptimisation
+ */
+class test_WriteFontCss extends FilesystemTestCase {
+    protected function setUp(): void {
+        parent::setUp();
+
+        Functions\when( 'get_current_blog_id' )->justReturn( 1 );
+    }
+
+
+    /**
+     * @dataProvider providerTestData
+     */
+    public function testShouldReturnExpected( $url, $file ) {
+        $filesystem = new Filesystem( $this->filesystem->getUrl( 'wp-content/cache/wp-rocket/fonts/' ) );
+
+
+    }
+}