diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 3cc29bb..691376e 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,20 +1,21 @@
 <?xml version="1.0"?>
 <phpunit
-	bootstrap="tests/bootstrap.php"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.5/phpunit.xsd"
+	bootstrap="tests/phpunit/bootstrap.php"
 	backupGlobals="false"
 	colors="true"
-	convertErrorsToExceptions="true"
-	convertNoticesToExceptions="true"
-	convertWarningsToExceptions="true"
+	beStrictAboutTestsThatDoNotTestAnything="true"
+	beStrictAboutOutputDuringTests="true"
 >
 	<testsuites>
-		<testsuite name="IndieWeb">
-			<directory prefix="test-" suffix=".php">./tests/</directory>
+		<testsuite name="Indieweb">
+			<directory prefix="class-test-" suffix=".php">tests/phpunit/tests/</directory>
 		</testsuite>
 	</testsuites>
-	<coverage>
+	<source>
 		<include>
 			<directory suffix=".php">./includes</directory>
 		</include>
-	</coverage>
+	</source>
 </phpunit>
diff --git a/tests/bootstrap.php b/tests/phpunit/bootstrap.php
similarity index 60%
rename from tests/bootstrap.php
rename to tests/phpunit/bootstrap.php
index 984dcb3..434daf8 100644
--- a/tests/bootstrap.php
+++ b/tests/phpunit/bootstrap.php
@@ -1,37 +1,44 @@
 <?php
 /**
- * PHPUnit bootstrap file
+ * PHPUnit bootstrap file.
  *
- * @package IndieWeb
+ * @package Indieweb
  */
 
+define( 'INDIEWEB_TESTS_DIR', __DIR__ );
+
+// Forward custom PHPUnit Polyfills configuration to PHPUnit bootstrap file.
+$_phpunit_polyfills_path = getenv( 'WP_TESTS_PHPUNIT_POLYFILLS_PATH' );
+if ( false !== $_phpunit_polyfills_path ) {
+	define( 'WP_TESTS_PHPUNIT_POLYFILLS_PATH', $_phpunit_polyfills_path );
+}
+
 $_tests_dir = getenv( 'WP_TESTS_DIR' );
 
 if ( ! $_tests_dir ) {
 	$_tests_dir = rtrim( sys_get_temp_dir(), '/\\' ) . '/wordpress-tests-lib';
 }
 
-if ( ! file_exists( $_tests_dir . '/includes/functions.php' ) ) {
-	echo "Could not find $_tests_dir/includes/functions.php, have you run bin/install-wp-tests.sh ?" . PHP_EOL; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
-	exit( 1 );
+if ( ! is_dir( $_tests_dir ) ) {
+	$_tests_dir = rtrim( sys_get_temp_dir(), '/\\' ) . '/classicpress-tests-lib';
 }
 
-// Forward custom PHPUnit Polyfills configuration to PHPUnit bootstrap file.
-$_phpunit_polyfills_path = getenv( 'WP_TESTS_PHPUNIT_POLYFILLS_PATH' );
-if ( false !== $_phpunit_polyfills_path ) {
-	define( 'WP_TESTS_PHPUNIT_POLYFILLS_PATH', $_phpunit_polyfills_path );
-} elseif ( file_exists( dirname( __DIR__ ) . '/vendor/yoast/phpunit-polyfills/phpunitpolyfills-autoload.php' ) ) {
-	define( 'WP_TESTS_PHPUNIT_POLYFILLS_PATH', dirname( __DIR__ ) . '/vendor/yoast/phpunit-polyfills' );
+if ( ! file_exists( $_tests_dir . '/includes/functions.php' ) ) {
+	echo "Could not find {$_tests_dir}/includes/functions.php, have you run bin/install-wp-tests.sh ?" . PHP_EOL; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
+	exit( 1 );
 }
 
 // Give access to tests_add_filter() function.
 require_once $_tests_dir . '/includes/functions.php';
 
+// Load PHPUnit Polyfills.
+require_once dirname( __DIR__, 2 ) . '/vendor/yoast/phpunit-polyfills/phpunitpolyfills-autoload.php';
+
 /**
  * Manually load the plugin being tested.
  */
 function _manually_load_plugin() {
-	require dirname( __DIR__ ) . '/indieweb.php';
+	require dirname( __DIR__, 2 ) . '/indieweb.php';
 }
 tests_add_filter( 'muplugins_loaded', '_manually_load_plugin' );
 
diff --git a/tests/phpunit/tests/includes/class-test-indieweb.php b/tests/phpunit/tests/includes/class-test-indieweb.php
new file mode 100644
index 0000000..0a90dda
--- /dev/null
+++ b/tests/phpunit/tests/includes/class-test-indieweb.php
@@ -0,0 +1,85 @@
+<?php
+/**
+ * Test Indieweb class.
+ *
+ * @package Indieweb
+ */
+
+/**
+ * Test Indieweb class.
+ */
+class Test_Indieweb extends WP_UnitTestCase {
+
+	/**
+	 * Test that the plugin version constant is defined.
+	 */
+	public function test_version_constant_defined() {
+		$this->assertTrue( defined( 'INDIEWEB_VERSION' ) );
+		$this->assertNotEmpty( INDIEWEB_VERSION );
+	}
+
+	/**
+	 * Test that plugin constants are defined.
+	 */
+	public function test_plugin_constants_defined() {
+		$this->assertTrue( defined( 'INDIEWEB_PLUGIN_DIR' ) );
+		$this->assertTrue( defined( 'INDIEWEB_PLUGIN_BASENAME' ) );
+		$this->assertTrue( defined( 'INDIEWEB_PLUGIN_FILE' ) );
+		$this->assertTrue( defined( 'INDIEWEB_PLUGIN_URL' ) );
+	}
+
+	/**
+	 * Test that the singleton returns an instance.
+	 */
+	public function test_get_instance() {
+		$instance = \Indieweb\Indieweb::get_instance();
+
+		$this->assertInstanceOf( \Indieweb\Indieweb::class, $instance );
+	}
+
+	/**
+	 * Test that get_instance returns the same instance.
+	 */
+	public function test_singleton_returns_same_instance() {
+		$instance1 = \Indieweb\Indieweb::get_instance();
+		$instance2 = \Indieweb\Indieweb::get_instance();
+
+		$this->assertSame( $instance1, $instance2 );
+	}
+
+	/**
+	 * Test that get_version returns the version constant.
+	 */
+	public function test_get_version() {
+		$instance = \Indieweb\Indieweb::get_instance();
+
+		$this->assertEquals( INDIEWEB_VERSION, $instance->get_version() );
+	}
+
+	/**
+	 * Test that the version function exists and returns version.
+	 */
+	public function test_version_function() {
+		$this->assertEquals( INDIEWEB_VERSION, \Indieweb\version() );
+	}
+
+	/**
+	 * Test that hooks are registered after init.
+	 */
+	public function test_hooks_registered() {
+		$instance = \Indieweb\Indieweb::get_instance();
+		$instance->init();
+
+		$this->assertNotFalse( has_action( 'wp_enqueue_scripts', array( $instance, 'enqueue_style' ) ) );
+		$this->assertNotFalse( has_action( 'admin_enqueue_scripts', array( $instance, 'enqueue_admin_style' ) ) );
+		$this->assertNotFalse( has_action( 'admin_menu', array( $instance, 'add_menu_item' ) ) );
+		$this->assertNotFalse( has_action( 'admin_init', array( $instance, 'privacy_declaration' ) ) );
+	}
+
+	/**
+	 * Test that the indieweb_loaded action is fired.
+	 */
+	public function test_indieweb_loaded_action_fired() {
+		$this->assertNotFalse( did_action( 'indieweb_loaded' ) );
+	}
+}
diff --git a/tests/phpunit/tests/includes/hcard/class-test-user.php b/tests/phpunit/tests/includes/hcard/class-test-user.php
new file mode 100644
index 0000000..67aafb9
--- /dev/null
+++ b/tests/phpunit/tests/includes/hcard/class-test-user.php
@@ -0,0 +1,190 @@
+<?php
+/**
+ * Test Hcard User class.
+ *
+ * @package Indieweb
+ */
+
+/**
+ * Test Hcard User class.
+ */
+class Test_Hcard_User extends WP_UnitTestCase {
+
+	/**
+	 * Test user ID.
+	 *
+	 * @var int
+	 */
+	protected static $user_id;
+
+	/**
+	 * Set up before class.
+	 *
+	 * @param WP_UnitTest_Factory $factory Factory instance.
+	 */
+	public static function wpSetUpBeforeClass( WP_UnitTest_Factory $factory ) {
+		self::$user_id = $factory->user->create(
+			array(
+				'role'         => 'administrator',
+				'display_name' => 'Test User',
+				'user_url'     => 'https://example.com',
+			)
+		);
+	}
+
+	/**
+	 * Test that silos returns an array.
+	 */
+	public function test_silos_returns_array() {
+		$silos = \Indieweb\Hcard\User::silos();
+
+		$this->assertIsArray( $silos );
+		$this->assertNotEmpty( $silos );
+	}
+
+	/**
+	 * Test that silos contains expected keys.
+	 */
+	public function test_silos_contains_expected_keys() {
+		$silos = \Indieweb\Hcard\User::silos();
+
+		$this->assertArrayHasKey( 'github', $silos );
+		$this->assertArrayHasKey( 'twitter', $silos );
+		$this->assertArrayHasKey( 'mastodon', $silos );
+		$this->assertArrayHasKey( 'bluesky', $silos );
+	}
+
+	/**
+	 * Test that silos have required structure.
+	 */
+	public function test_silos_have_required_structure() {
+		$silos = \Indieweb\Hcard\User::silos();
+
+		foreach ( $silos as $silo => $details ) {
+			$this->assertArrayHasKey( 'baseurl', $details, "Silo {$silo} should have baseurl" );
+			$this->assertArrayHasKey( 'display', $details, "Silo {$silo} should have display" );
+		}
+	}
+
+	/**
+	 * Test address fields returns an array.
+	 */
+	public function test_address_fields_returns_array() {
+		$fields = \Indieweb\Hcard\User::address_fields();
+
+		$this->assertIsArray( $fields );
+		$this->assertNotEmpty( $fields );
+	}
+
+	/**
+	 * Test address fields contains expected keys.
+	 */
+	public function test_address_fields_contains_expected_keys() {
+		$fields = \Indieweb\Hcard\User::address_fields();
+
+		$this->assertArrayHasKey( 'street_address', $fields );
+		$this->assertArrayHasKey( 'locality', $fields );
+		$this->assertArrayHasKey( 'region', $fields );
+		$this->assertArrayHasKey( 'postal_code', $fields );
+		$this->assertArrayHasKey( 'country_name', $fields );
+	}
+
+	/**
+	 * Test extra fields returns an array.
+	 */
+	public function test_extra_fields_returns_array() {
+		$fields = \Indieweb\Hcard\User::extra_fields();
+
+		$this->assertIsArray( $fields );
+		$this->assertNotEmpty( $fields );
+	}
+
+	/**
+	 * Test extra fields contains expected keys.
+	 */
+	public function test_extra_fields_contains_expected_keys() {
+		$fields = \Indieweb\Hcard\User::extra_fields();
+
+		$this->assertArrayHasKey( 'job_title', $fields );
+		$this->assertArrayHasKey( 'organization', $fields );
+		$this->assertArrayHasKey( 'honorific_prefix', $fields );
+	}
+
+	/**
+	 * Test clean_url with valid URL.
+	 */
+	public function test_clean_url_with_valid_url() {
+		$url    = 'https://example.com/path';
+		$result = \Indieweb\Hcard\User::clean_url( $url );
+
+		$this->assertEquals( $url, $result );
+	}
+
+	/**
+	 * Test clean_url with invalid URL.
+	 */
+	public function test_clean_url_with_invalid_url() {
+		$result = \Indieweb\Hcard\User::clean_url( 'not-a-url' );
+
+		$this->assertFalse( $result );
+	}
+
+	/**
+	 * Test clean_url upgrades http to https for known domains.
+	 */
+	public function test_clean_url_upgrades_http_to_https() {
+		$result = \Indieweb\Hcard\User::clean_url( 'http://github.com/user' );
+
+		$this->assertStringStartsWith( 'https://', $result );
+	}
+
+	/**
+	 * Test clean_urls filters array of URLs.
+	 */
+	public function test_clean_urls_filters_array() {
+		$urls   = array(
+			'https://example.com',
+			'not-a-url',
+			'https://example.org',
+			'',
+		);
+		$result = \Indieweb\Hcard\User::clean_urls( $urls );
+
+		$this->assertCount( 2, $result );
+		$this->assertContains( 'https://example.com', $result );
+		$this->assertContains( 'https://example.org', $result );
+	}
+
+	/**
+	 * Test get_hcard_display_defaults returns array.
+	 */
+	public function test_get_hcard_display_defaults() {
+		$defaults = \Indieweb\Hcard\User::get_hcard_display_defaults();
+
+		$this->assertIsArray( $defaults );
+		$this->assertArrayHasKey( 'avatar', $defaults );
+		$this->assertArrayHasKey( 'location', $defaults );
+		$this->assertArrayHasKey( 'notes', $defaults );
+		$this->assertArrayHasKey( 'email', $defaults );
+		$this->assertArrayHasKey( 'me', $defaults );
+	}
+
+	/**
+	 * Test hcard returns false for invalid user.
+	 */
+	public function test_hcard_returns_false_for_invalid_user() {
+		$result = \Indieweb\Hcard\User::hcard( null );
+
+		$this->assertFalse( $result );
+	}
+
+	/**
+	 * Test hcard returns string for valid user.
+	 */
+	public function test_hcard_returns_string_for_valid_user() {
+		$result = \Indieweb\Hcard\User::hcard( self::$user_id );
+
+		$this->assertIsString( $result );
+		$this->assertStringContainsString( 'h-card', $result );
+	}
+}
diff --git a/tests/phpunit/tests/includes/relme/class-test-domain-icon-map.php b/tests/phpunit/tests/includes/relme/class-test-domain-icon-map.php
new file mode 100644
index 0000000..1b94005
--- /dev/null
+++ b/tests/phpunit/tests/includes/relme/class-test-domain-icon-map.php
@@ -0,0 +1,150 @@
+<?php
+/**
+ * Test Relme Domain_Icon_Map class.
+ *
+ * @package Indieweb
+ */
+
+/**
+ * Test Relme Domain_Icon_Map class.
+ */
+class Test_Relme_Domain_Icon_Map extends WP_UnitTestCase {
+
+	/**
+	 * Test split_domain with two-part domain.
+	 */
+	public function test_split_domain_two_parts() {
+		$result = \Indieweb\Relme\Domain_Icon_Map::split_domain( 'example.com' );
+
+		$this->assertEquals( 'example', $result );
+	}
+
+	/**
+	 * Test split_domain with three-part domain.
+	 */
+	public function test_split_domain_three_parts() {
+		$result = \Indieweb\Relme\Domain_Icon_Map::split_domain( 'www.example.com' );
+
+		$this->assertEquals( 'example', $result );
+	}
+
+	/**
+	 * Test split_domain with single part.
+	 */
+	public function test_split_domain_single_part() {
+		$result = \Indieweb\Relme\Domain_Icon_Map::split_domain( 'localhost' );
+
+		$this->assertEquals( 'localhost', $result );
+	}
+
+	/**
+	 * Test url_to_name with known domain.
+	 */
+	public function test_url_to_name_known_domain() {
+		$result = \Indieweb\Relme\Domain_Icon_Map::url_to_name( 'https://github.com/user' );
+
+		$this->assertEquals( 'github', $result );
+	}
+
+	/**
+	 * Test url_to_name with Twitter.
+	 */
+	public function test_url_to_name_twitter() {
+		$result = \Indieweb\Relme\Domain_Icon_Map::url_to_name( 'https://twitter.com/username' );
+
+		$this->assertEquals( 'twitter', $result );
+	}
+
+	/**
+	 * Test url_to_name with Bluesky.
+	 */
+	public function test_url_to_name_bluesky() {
+		$result = \Indieweb\Relme\Domain_Icon_Map::url_to_name( 'https://bsky.app/profile/user.bsky.social' );
+
+		$this->assertEquals( 'bluesky', $result );
+	}
+
+	/**
+	 * Test url_to_name with mailto scheme.
+	 */
+	public function test_url_to_name_mailto() {
+		$result = \Indieweb\Relme\Domain_Icon_Map::url_to_name( 'mailto:test@example.com' );
+
+		$this->assertEquals( 'mail', $result );
+	}
+
+	/**
+	 * Test url_to_name with sms scheme.
+	 */
+	public function test_url_to_name_sms() {
+		$result = \Indieweb\Relme\Domain_Icon_Map::url_to_name( 'sms:+1234567890' );
+
+		$this->assertEquals( 'phone', $result );
+	}
+
+	/**
+	 * Test url_to_name with unknown domain returns website.
+	 */
+	public function test_url_to_name_unknown_domain() {
+		$result = \Indieweb\Relme\Domain_Icon_Map::url_to_name( 'https://unknowndomain12345.com' );
+
+		$this->assertEquals( 'website', $result );
+	}
+
+	/**
+	 * Test url_to_name with non-http scheme returns notice.
+	 */
+	public function test_url_to_name_non_http() {
+		$result = \Indieweb\Relme\Domain_Icon_Map::url_to_name( 'ftp://example.com' );
+
+		$this->assertEquals( 'notice', $result );
+	}
+
+	/**
+	 * Test get_title returns name when not found.
+	 */
+	public function test_get_title_returns_name_when_not_found() {
+		$result = \Indieweb\Relme\Domain_Icon_Map::get_title( 'unknownicon12345' );
+
+		$this->assertEquals( 'unknownicon12345', $result );
+	}
+
+	/**
+	 * Test get_icon_filename returns null for non-existent icon.
+	 */
+	public function test_get_icon_filename_returns_null_for_nonexistent() {
+		$result = \Indieweb\Relme\Domain_Icon_Map::get_icon_filename( 'nonexistenticon12345' );
+
+		$this->assertNull( $result );
+	}
+
+	/**
+	 * Test get_icon returns name for non-existent icon.
+	 */
+	public function test_get_icon_returns_name_for_nonexistent() {
+		$result = \Indieweb\Relme\Domain_Icon_Map::get_icon( 'nonexistenticon12345' );
+
+		$this->assertEquals( 'nonexistenticon12345', $result );
+	}
+
+	/**
+	 * Test url_to_name filter is applied.
+	 */
+	public function test_url_to_name_filter() {
+		add_filter(
+			'indieweb_links_url_to_name',
+			function ( $name, $url ) {
+				if ( strpos( $url, 'custom.example.com' ) !== false ) {
+					return 'custom';
+				}
+				return $name;
+			},
+			10,
+			2
+		);
+
+		$result = \Indieweb\Relme\Domain_Icon_Map::url_to_name( 'https://custom.example.com' );
+
+		$this->assertEquals( 'custom', $result );
+	}
+}
diff --git a/tests/test-microformats.php b/tests/test-microformats.php
deleted file mode 100644
index 86c49b3..0000000
--- a/tests/test-microformats.php
+++ /dev/null
@@ -1,18 +0,0 @@
-<?php
-/**
- * Microformats test case.
- *
- * @package IndieWeb
- */
-
-/**
- * Test class for Microformats functionality.
- */
-class MicroformatsTest extends WP_UnitTestCase {
-	/**
-	 * Basic test placeholder.
-	 */
-	public function test() {
-		$this->assertTrue( true );
-	}
-}