diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index 853a419..a0ee43d 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -6,8 +6,11 @@ parameters:
 	level: 9
 	paths:
 		- user-switching.php
+		- tests/acceptance
+		- tests/integration
 	scanDirectories:
 		- tests/_support/
+		- vendor/lucatume/wp-browser/src/includes/factory/
 	excludePaths:
 		analyse:
 			- tests/integration/Supports/
diff --git a/tests/acceptance/SwitchFromEnglishCest.php b/tests/acceptance/SwitchFromEnglishCest.php
index 7edbd76..48501cf 100644
--- a/tests/acceptance/SwitchFromEnglishCest.php
+++ b/tests/acceptance/SwitchFromEnglishCest.php
@@ -1,10 +1,12 @@
-<?php
+<?php declare(strict_types = 1);
+
+namespace UserSwitching\Tests;
+
 /**
  * Acceptance tests for switching from a user who uses English to a user who doesn't
  */
-
-class SwitchFromEnglishCest {
-	public function _before( AcceptanceTester $I ) {
+final class SwitchFromEnglishCest {
+	public function _before( \AcceptanceTester $I ): void {
 		$I->comment( 'As an administrator of a site which uses more than one language' );
 		$I->comment( 'I need to be able to switch to user accounts that use a different language' );
 		$I->comment( 'And see the output of User Switching in my original language' );
@@ -17,7 +19,7 @@ public function _before( AcceptanceTester $I ) {
 		] );
 	}
 
-	public function SwitchFromEnglishAdminToItalianAuthorAndBack( AcceptanceTester $I ) {
+	public function SwitchFromEnglishAdminToItalianAuthorAndBack( \AcceptanceTester $I ): void {
 		$I->loginAsAdmin();
 		$I->switchToUser( 'autore' );
 		$I->canSeeThePageInLanguage( 'it-IT' );
diff --git a/tests/acceptance/SwitchOffCest.php b/tests/acceptance/SwitchOffCest.php
index 4228fc8..374f4bb 100644
--- a/tests/acceptance/SwitchOffCest.php
+++ b/tests/acceptance/SwitchOffCest.php
@@ -1,16 +1,18 @@
-<?php
+<?php declare(strict_types = 1);
+
+namespace UserSwitching\Tests;
+
 /**
  * Acceptance tests for switching off.
  */
-
-class SwitchOffCest {
-	public function _before( AcceptanceTester $I ) {
+final class SwitchOffCest {
+	public function _before( \AcceptanceTester $I ): void {
 		$I->comment( 'As an administrator' );
 		$I->comment( 'I need to be able to switch off' );
 		$I->comment( 'In order to view the site without logging out completely' );
 	}
 
-	public function SwitchOffFromDashboardAndBackFromFrontEnd( AcceptanceTester $I ) {
+	public function SwitchOffFromDashboardAndBackFromFrontEnd( \AcceptanceTester $I ): void {
 		$I->loginAsAdmin();
 		$I->amOnAdminPage( '/' );
 		$I->switchOff();
@@ -22,7 +24,7 @@ public function SwitchOffFromDashboardAndBackFromFrontEnd( AcceptanceTester $I )
 		$I->amLoggedInAs( 'admin' );
 	}
 
-	public function SwitchOffFromDashboardAndBackFromLoginScreen( AcceptanceTester $I ) {
+	public function SwitchOffFromDashboardAndBackFromLoginScreen( \AcceptanceTester $I ): void {
 		$I->loginAsAdmin();
 		$I->amOnAdminPage( '/' );
 		$I->switchOff();
@@ -36,7 +38,7 @@ public function SwitchOffFromDashboardAndBackFromLoginScreen( AcceptanceTester $
 		$I->amLoggedInAs( 'admin' );
 	}
 
-	public function SwitchOffFromPublishedPostEditingScreen( AcceptanceTester $I ) {
+	public function SwitchOffFromPublishedPostEditingScreen( \AcceptanceTester $I ): void {
 		$I->loginAsAdmin();
 		$id = $I->havePostInDatabase( [
 			'post_status' => 'publish',
@@ -49,7 +51,7 @@ public function SwitchOffFromPublishedPostEditingScreen( AcceptanceTester $I ) {
 		$I->amLoggedOut();
 	}
 
-	public function SwitchOffFromDraftPostEditingScreen( AcceptanceTester $I ) {
+	public function SwitchOffFromDraftPostEditingScreen( \AcceptanceTester $I ): void {
 		$I->loginAsAdmin();
 		$id = $I->havePostInDatabase( [
 			'post_status' => 'draft',
@@ -62,7 +64,7 @@ public function SwitchOffFromDraftPostEditingScreen( AcceptanceTester $I ) {
 		$I->amLoggedOut();
 	}
 
-	public function SwitchOffFromTermEditingScreen( AcceptanceTester $I ) {
+	public function SwitchOffFromTermEditingScreen( \AcceptanceTester $I ): void {
 		$I->loginAsAdmin();
 		$term = $I->haveTermInDatabase( 'hello', 'category' );
 		$I->amOnAdminPage( '/term.php?taxonomy=category&tag_ID=' . $term[0] );
@@ -79,7 +81,7 @@ public function SwitchOffFromTermEditingScreen( AcceptanceTester $I ) {
 		$I->amLoggedOut();
 	}
 
-	public function SwitchOffFromUserEditingScreen( AcceptanceTester $I ) {
+	public function SwitchOffFromUserEditingScreen( \AcceptanceTester $I ): void {
 		$I->loginAsAdmin();
 		$id = $I->haveUserInDatabase( 'example', 'editor' );
 		// https://github.com/lucatume/wp-browser/pull/586
@@ -90,7 +92,7 @@ public function SwitchOffFromUserEditingScreen( AcceptanceTester $I ) {
 		$I->amLoggedOut();
 	}
 
-	public function SwitchOffFromApprovedCommentEditingScreen( AcceptanceTester $I ) {
+	public function SwitchOffFromApprovedCommentEditingScreen( \AcceptanceTester $I ): void {
 		$I->loginAsAdmin();
 		$postId = $I->havePostInDatabase( [
 			'post_status' => 'publish',
@@ -105,7 +107,7 @@ public function SwitchOffFromApprovedCommentEditingScreen( AcceptanceTester $I )
 		$I->amLoggedOut();
 	}
 
-	public function SwitchOffFromUnapprovedCommentEditingScreen( AcceptanceTester $I ) {
+	public function SwitchOffFromUnapprovedCommentEditingScreen( \AcceptanceTester $I ): void {
 		$I->loginAsAdmin();
 		$postId = $I->havePostInDatabase( [
 			'post_status' => 'publish',
diff --git a/tests/acceptance/SwitchToEnglishCest.php b/tests/acceptance/SwitchToEnglishCest.php
index 947bbc2..3db08e0 100644
--- a/tests/acceptance/SwitchToEnglishCest.php
+++ b/tests/acceptance/SwitchToEnglishCest.php
@@ -1,10 +1,12 @@
-<?php
+<?php declare(strict_types = 1);
+
+namespace UserSwitching\Tests;
+
 /**
  * Acceptance tests for switching from a user who doesn't use English to a user who does
  */
-
-class SwitchToEnglishCest {
-	public function _before( AcceptanceTester $I ) {
+final class SwitchToEnglishCest {
+	public function _before( \AcceptanceTester $I ): void {
 		$I->comment( 'As an administrator of a site which uses more than one language' );
 		$I->comment( 'I need to be able to switch between users' );
 		$I->comment( 'And see the output of User Switching in my original language' );
@@ -20,7 +22,7 @@ public function _before( AcceptanceTester $I ) {
 		] );
 	}
 
-	public function SwitchFromItalianAdminToEnglishAuthorAndBack( AcceptanceTester $I ) {
+	public function SwitchFromItalianAdminToEnglishAuthorAndBack( \AcceptanceTester $I ): void {
 		$I->loginAs( 'admin_it', 'admin_it' );
 		$I->switchToUser( 'author_en' );
 		$I->canSeeThePageInLanguage( 'en-US' );
diff --git a/tests/acceptance/SwitchUserCest.php b/tests/acceptance/SwitchUserCest.php
index 8cd77f7..ecd39ce 100644
--- a/tests/acceptance/SwitchUserCest.php
+++ b/tests/acceptance/SwitchUserCest.php
@@ -1,16 +1,18 @@
-<?php
+<?php declare(strict_types = 1);
+
+namespace UserSwitching\Tests;
+
 /**
  * Acceptance tests for switching users.
  */
-
-class SwitchUserCest {
-	public function _before( AcceptanceTester $I ) {
+final class SwitchUserCest {
+	public function _before( \AcceptanceTester $I ): void {
 		$I->comment( 'As an administrator' );
 		$I->comment( 'I need to be able to switch between users' );
 		$I->comment( 'In order to access different user accounts' );
 	}
 
-	public function SwitchToEditorThenBackFromFrontEnd( AcceptanceTester $I ) {
+	public function SwitchToEditorThenBackFromFrontEnd( \AcceptanceTester $I ): void {
 		$I->loginAsAdmin();
 		$I->haveUserInDatabase( 'editor', 'editor' );
 
@@ -25,7 +27,7 @@ public function SwitchToEditorThenBackFromFrontEnd( AcceptanceTester $I ) {
 		$I->amLoggedInAs( 'admin' );
 	}
 
-	public function SwitchToEditorThenBackFromAdminArea( AcceptanceTester $I ) {
+	public function SwitchToEditorThenBackFromAdminArea( \AcceptanceTester $I ): void {
 		$I->loginAsAdmin();
 		$I->haveUserInDatabase( 'editor', 'editor' );
 
diff --git a/tests/integration/Test.php b/tests/integration/Test.php
index 9bd861e..60c0fa8 100644
--- a/tests/integration/Test.php
+++ b/tests/integration/Test.php
@@ -1,25 +1,22 @@
-<?php
-
-declare(strict_types = 1);
+<?php declare(strict_types = 1);
 
 namespace UserSwitching\Tests;
 
 abstract class Test extends \Codeception\TestCase\WPTestCase {
-
 	/**
 	 * @var array<string, \WP_User>
 	 */
-	protected static $users = array();
+	protected static $users = [];
 
 	/**
 	 * @var array<string, \WP_User>
 	 */
-	protected static $testers = array();
+	protected static $testers = [];
 
 	/**
 	 * @var array<int, string>
 	 */
-	protected $sessions = array();
+	protected $sessions = [];
 
 	/**
 	 * @return void
@@ -57,48 +54,51 @@ public static function wpSetUpBeforeClass( \WP_UnitTest_Factory $factory ) {
 		add_filter( 'user_switching_send_auth_cookies', '__return_false' );
 	}
 
-	/**
-	 * @return void
-	 */
-	public function _before() {
+	public function _before(): void {
 		add_action( 'set_auth_cookie',           array( $this, 'action_set_auth_cookie' ), 10, 6 );
-		add_action( 'set_logged_in_cookie',      array( $this, 'action_set_logged_in_cookie' ), 10, 6 );
+		add_action( 'set_logged_in_cookie',      array( $this, 'action_set_logged_in_cookie' ), 10 );
 		add_action( 'clear_auth_cookie',         array( $this, 'action_clear_auth_cookie' ) );
 
-		add_action( 'set_user_switching_cookie', array( $this, 'action_set_user_switching_cookie' ), 10, 5 );
-		add_action( 'set_olduser_cookie',        array( $this, 'action_set_olduser_cookie' ), 10, 5 );
+		add_action( 'set_user_switching_cookie', array( $this, 'action_set_user_switching_cookie' ), 10 );
+		add_action( 'set_olduser_cookie',        array( $this, 'action_set_olduser_cookie' ), 10 );
 		add_action( 'clear_olduser_cookie',      array( $this, 'action_clear_olduser_cookie' ) );
 	}
 
-	public function action_set_auth_cookie( $cookie, $expire, $expiration, $user_id, $scheme, $token ) {
+	final public function action_set_auth_cookie(
+		string $cookie,
+		int $expire,
+		int $expiration,
+		int $user_id,
+		string $scheme,
+		string $token
+	): void {
 		$_COOKIE[ SECURE_AUTH_COOKIE ] = $cookie;
 		$_COOKIE[ AUTH_COOKIE ] = $cookie;
 		$this->sessions[ $user_id ] = $token;
 	}
 
-	public function action_set_logged_in_cookie( $cookie, $expire, $expiration, $user_id, $scheme, $token ) {
+	final public function action_set_logged_in_cookie( string $cookie ): void {
 		$_COOKIE[ LOGGED_IN_COOKIE ] = $cookie;
 	}
 
-	public function action_clear_auth_cookie() {
+	final public function action_clear_auth_cookie(): void {
 		unset( $_COOKIE[ LOGGED_IN_COOKIE ] );
 		unset( $_COOKIE[ SECURE_AUTH_COOKIE ] );
 		unset( $_COOKIE[ AUTH_COOKIE ] );
 	}
 
-	public function action_set_user_switching_cookie( $cookie, $expiration, $user_id, $scheme, $token ) {
+	final public function action_set_user_switching_cookie( string $cookie ): void {
 		$_COOKIE[ USER_SWITCHING_COOKIE ] = $cookie;
 		$_COOKIE[ USER_SWITCHING_SECURE_COOKIE ] = $cookie;
 	}
 
-	public function action_set_olduser_cookie( $cookie, $expiration, $user_id, $scheme, $token ) {
+	final public function action_set_olduser_cookie( string $cookie ): void {
 		$_COOKIE[ USER_SWITCHING_OLDUSER_COOKIE ] = $cookie;
 	}
 
-	public function action_clear_olduser_cookie() {
+	final public function action_clear_olduser_cookie(): void {
 		unset( $_COOKIE[ USER_SWITCHING_COOKIE ] );
 		unset( $_COOKIE[ USER_SWITCHING_SECURE_COOKIE ] );
 		unset( $_COOKIE[ USER_SWITCHING_OLDUSER_COOKIE ] );
 	}
-
 }
diff --git a/tests/integration/authenticationTest.php b/tests/integration/authenticationTest.php
index 0c40416..1e3747f 100644
--- a/tests/integration/authenticationTest.php
+++ b/tests/integration/authenticationTest.php
@@ -1,6 +1,4 @@
-<?php
-
-declare(strict_types = 1);
+<?php declare(strict_types = 1);
 
 namespace UserSwitching\Tests;
 
@@ -9,9 +7,8 @@
 /**
  * @covers \user_switching::authenticate_old_user
  */
-class AuthenticationTest extends Test {
-
-	public function testValidCookiePassesAuthentication() {
+final class AuthenticationTest extends Test {
+	public function testValidCookiePassesAuthentication(): void {
 		$expiry = time() + 172800;
 
 		$auth_cookie = wp_generate_auth_cookie( self::$testers['editor']->ID, $expiry, 'auth' );
@@ -20,14 +17,14 @@ public function testValidCookiePassesAuthentication() {
 		self::assertFalse( user_switching::authenticate_old_user( self::$testers['admin'] ) );
 	}
 
-	public function testExpiredCookieDoesNotPassAuthentication() {
+	public function testExpiredCookieDoesNotPassAuthentication(): void {
 		$auth_cookie = wp_generate_auth_cookie( self::$testers['editor']->ID, time() - 1000, 'auth' );
 		$_COOKIE[ USER_SWITCHING_COOKIE ] = json_encode( array( $auth_cookie ) );
 		self::assertFalse( user_switching::authenticate_old_user( self::$testers['editor'] ) );
 		self::assertFalse( user_switching::authenticate_old_user( self::$testers['admin'] ) );
 	}
 
-	public function testValidCookieWithIncorrectSchemeDoesNotPassAuthentication() {
+	public function testValidCookieWithIncorrectSchemeDoesNotPassAuthentication(): void {
 		$expiry = time() + 172800;
 
 		$logged_in_cookie = wp_generate_auth_cookie( self::$testers['editor']->ID, $expiry, 'logged_in' );
@@ -40,16 +37,13 @@ public function testValidCookieWithIncorrectSchemeDoesNotPassAuthentication() {
 		self::assertFalse( user_switching::authenticate_old_user( self::$testers['admin'] ) );
 	}
 
-	public function testMalformedCookieDoesNotPassAuthentication() {
+	public function testMalformedCookieDoesNotPassAuthentication(): void {
 		$_COOKIE[ USER_SWITCHING_COOKIE ] = 'hello';
 		self::assertFalse( user_switching::authenticate_old_user( self::$testers['editor'] ) );
 		self::assertFalse( user_switching::authenticate_old_user( self::$testers['admin'] ) );
 	}
 
-	/**
-	 * @testdox A non-JSON encoded cookie does not pass authentication
-	 */
-	public function testANonJsonEncodedCookieDoesNotPassAuthentication() {
+	public function testANonJsonEncodedCookieDoesNotPassAuthentication(): void {
 		$expiry = time() + 172800;
 
 		$auth_cookie = wp_generate_auth_cookie( self::$testers['editor']->ID, $expiry, 'auth' );
@@ -58,10 +52,9 @@ public function testANonJsonEncodedCookieDoesNotPassAuthentication() {
 		self::assertFalse( user_switching::authenticate_old_user( self::$testers['admin'] ) );
 	}
 
-	public function testNoCookieDoesNotPassAuthentication() {
+	public function testNoCookieDoesNotPassAuthentication(): void {
 		unset( $_COOKIE[ USER_SWITCHING_COOKIE ] );
 		self::assertFalse( user_switching::authenticate_old_user( self::$testers['editor'] ) );
 		self::assertFalse( user_switching::authenticate_old_user( self::$testers['admin'] ) );
 	}
-
 }
diff --git a/tests/integration/capabilitiesTest.php b/tests/integration/capabilitiesTest.php
index e49f282..edd0316 100644
--- a/tests/integration/capabilitiesTest.php
+++ b/tests/integration/capabilitiesTest.php
@@ -1,6 +1,4 @@
-<?php
-
-declare(strict_types = 1);
+<?php declare(strict_types = 1);
 
 namespace UserSwitching\Tests;
 
@@ -8,12 +6,11 @@
  * @covers \user_switching::filter_user_has_cap
  * @covers \user_switching::filter_map_meta_cap
  */
-class CapabilitiesTest extends Test {
-
+final class CapabilitiesTest extends Test {
 	/**
 	 * @return array<string, array<int, string|bool>>
 	 */
-	public function data_roles() {
+	public function data_roles(): array {
 		$roles = [
 			'admin' => [
 				'admin',
@@ -51,7 +48,7 @@ public function data_roles() {
 		return $roles;
 	}
 
-	public function testAllRolesAreTested() {
+	public function testAllRolesAreTested(): void {
 		$tested_roles = array_column( $this->data_roles(), 0 );
 
 		self::assertSame( array_keys( self::$testers ), $tested_roles );
@@ -60,9 +57,8 @@ public function testAllRolesAreTested() {
 
 	/**
 	 * @dataProvider data_roles
-	 * @testdox User with role of $role can or cannot switch according to role
 	 */
-	public function testUserCanOrCannotSwitchAccordingToRole( $role, $can_switch ) {
+	public function testUserCanOrCannotSwitchAccordingToRole( string $role, bool $can_switch ): void {
 		foreach ( self::$users as $user_role => $user ) {
 			if ( self::$testers[ $role ]->ID === $user->ID ) {
 				# No user can switch to themselves:
@@ -80,7 +76,7 @@ public function testUserCanOrCannotSwitchAccordingToRole( $role, $can_switch ) {
 		self::assertSame( $can_switch, user_can( self::$testers[ $role ]->ID, 'switch_off' ) );
 	}
 
-	public function testAbilityToSwitchUsersCanBeGrantedToUser() {
+	public function testAbilityToSwitchUsersCanBeGrantedToUser(): void {
 		# Editors cannot switch to other users:
 		$can_already_switch = user_can( self::$testers['editor']->ID, 'switch_to_user', self::$users['admin']->ID );
 
@@ -100,7 +96,7 @@ public function testAbilityToSwitchUsersCanBeGrantedToUser() {
 		self::assertTrue( $can_switch_off );
 	}
 
-	public function testAbilityToSwitchUsersCanBeGrantedToRole() {
+	public function testAbilityToSwitchUsersCanBeGrantedToRole(): void {
 		# Editors cannot switch to other users:
 		$can_already_switch = user_can( self::$testers['editor']->ID, 'switch_to_user', self::$users['admin']->ID );
 
@@ -126,7 +122,7 @@ public function testAbilityToSwitchUsersCanBeGrantedToRole() {
 	/**
 	 * @group ms-excluded
 	 */
-	public function testAbilityToSwitchUsersCanBeDeniedFromUser() {
+	public function testAbilityToSwitchUsersCanBeDeniedFromUser(): void {
 		# Admins can switch to other users:
 		$can_already_switch = user_can( self::$testers['admin']->ID, 'switch_to_user', self::$users['author']->ID );
 
@@ -149,7 +145,7 @@ public function testAbilityToSwitchUsersCanBeDeniedFromUser() {
 	/**
 	 * @group ms-excluded
 	 */
-	public function testAbilityToSwitchUsersCanBeDeniedFromRole() {
+	public function testAbilityToSwitchUsersCanBeDeniedFromRole(): void {
 		# Admins can switch to other users:
 		$can_already_switch = user_can( self::$testers['admin']->ID, 'switch_to_user', self::$users['author']->ID );
 
@@ -176,7 +172,7 @@ public function testAbilityToSwitchUsersCanBeDeniedFromRole() {
 	 * @group multisite
 	 * @group ms-required
 	 */
-	public function testAbilityToSwitchUsersCanBeGrantedToAdministratorRoleOnMultisite() {
+	public function testAbilityToSwitchUsersCanBeGrantedToAdministratorRoleOnMultisite(): void {
 		# Admins on Multisite cannot switch to other users:
 		$can_already_switch = user_can( self::$testers['admin']->ID, 'switch_to_user', self::$users['author']->ID );
 
@@ -203,7 +199,7 @@ public function testAbilityToSwitchUsersCanBeGrantedToAdministratorRoleOnMultisi
 	 * @group multisite
 	 * @group ms-required
 	 */
-	public function testAbilityToSwitchUsersCanBeGrantedToAdministratorUserOnMultisite() {
+	public function testAbilityToSwitchUsersCanBeGrantedToAdministratorUserOnMultisite(): void {
 		# Admins on Multisite cannot switch to other users:
 		$can_already_switch = user_can( self::$testers['admin']->ID, 'switch_to_user', self::$users['author']->ID );
 
@@ -225,10 +221,8 @@ public function testAbilityToSwitchUsersCanBeGrantedToAdministratorUserOnMultisi
 
 	/**
 	 * @dataProvider data_roles
-	 * @testdox User with role of $role cannot switch to no user
 	 */
-	public function testSwitchingToNoUserIsNotAllowed( $role ) {
+	public function testSwitchingToNoUserIsNotAllowed( string $role ): void {
 		self::assertFalse( user_can( self::$testers[ $role ]->ID, 'switch_to_user', 0 ) );
 	}
-
 }
diff --git a/tests/integration/pluginTest.php b/tests/integration/pluginTest.php
index fb598e4..55a03df 100644
--- a/tests/integration/pluginTest.php
+++ b/tests/integration/pluginTest.php
@@ -1,16 +1,14 @@
-<?php
-
-declare(strict_types = 1);
+<?php declare(strict_types = 1);
 
 namespace UserSwitching\Tests;
 
-class PluginTest extends Test {
+final class PluginTest extends Test {
 	/**
 	 * @var ?array<string, string>
 	 */
 	private $readme_data;
 
-	public function testStableTagMatchesVersion() {
+	public function testStableTagMatchesVersion(): void {
 		$readme_data = $this->get_readme();
 		if ( null === $readme_data ) {
 			self::fail( 'There is no readme file' );
@@ -24,7 +22,7 @@ public function testStableTagMatchesVersion() {
 	/**
 	 * @return ?array<string, string>
 	 */
-	private function get_readme() {
+	private function get_readme(): ?array {
 		if ( ! isset( $this->readme_data ) ) {
 			$file = dirname( dirname( __DIR__ ) ) . '/readme.md';
 
@@ -49,5 +47,4 @@ private function get_readme() {
 
 		return $this->readme_data;
 	}
-
 }
diff --git a/tests/integration/sessionsTest.php b/tests/integration/sessionsTest.php
index e04babd..8f21555 100644
--- a/tests/integration/sessionsTest.php
+++ b/tests/integration/sessionsTest.php
@@ -1,18 +1,15 @@
-<?php
-
-declare(strict_types = 1);
+<?php declare(strict_types = 1);
 
 namespace UserSwitching\Tests;
 
 use user_switching;
 use WP_Session_Tokens;
 
-class SessionsTest extends Test {
-
+final class SessionsTest extends Test {
 	/**
 	 * @covers \switch_to_user
 	 */
-	public function testExtraSessionsAreNotCreatedForUsersWhenSwitching() {
+	public function testExtraSessionsAreNotCreatedForUsersWhenSwitching(): void {
 		if ( is_multisite() ) {
 			$admin = self::$testers['super'];
 		} else {
@@ -49,7 +46,7 @@ public function testExtraSessionsAreNotCreatedForUsersWhenSwitching() {
 	/**
 	 * @covers \switch_off_user
 	 */
-	public function testExtraSessionsAreNotCreatedForUserWhenSwitchingOff() {
+	public function testExtraSessionsAreNotCreatedForUserWhenSwitchingOff(): void {
 		if ( is_multisite() ) {
 			$admin = self::$testers['super'];
 		} else {
@@ -79,7 +76,7 @@ public function testExtraSessionsAreNotCreatedForUserWhenSwitchingOff() {
 	 * @covers \switch_to_user
 	 * @covers \switch_off_user
 	 */
-	public function testPreviousSessionForUserIsReusedWhenSwitchingBack() {
+	public function testPreviousSessionForUserIsReusedWhenSwitchingBack(): void {
 		if ( is_multisite() ) {
 			$admin = self::$testers['super'];
 		} else {
@@ -132,7 +129,7 @@ public function testPreviousSessionForUserIsReusedWhenSwitchingBack() {
 	/**
 	 * @covers \switch_to_user
 	 */
-	public function testExpiredSessionPreventsUserFromSwitchingBack() {
+	public function testExpiredSessionPreventsUserFromSwitchingBack(): void {
 		if ( is_multisite() ) {
 			$admin = self::$testers['super'];
 		} else {
@@ -188,7 +185,7 @@ public function testExpiredSessionPreventsUserFromSwitchingBack() {
 	 * @covers \switch_to_user
 	 * @covers \switch_off_user
 	 */
-	public function testSessionTokensAreCorrectlyReusedWhenSwitching() {
+	public function testSessionTokensAreCorrectlyReusedWhenSwitching(): void {
 		if ( is_multisite() ) {
 			$admin = self::$testers['super'];
 		} else {
@@ -261,5 +258,4 @@ public function testSessionTokensAreCorrectlyReusedWhenSwitching() {
 		self::assertCount( 1, $admin_manager->get_all() );
 		self::assertNotNull( $admin_manager->get( $admin_token ) );
 	}
-
 }
diff --git a/tests/integration/switchingTest.php b/tests/integration/switchingTest.php
index 2beb005..4c7e016 100644
--- a/tests/integration/switchingTest.php
+++ b/tests/integration/switchingTest.php
@@ -1,34 +1,31 @@
-<?php
-
-declare(strict_types = 1);
+<?php declare(strict_types = 1);
 
 namespace UserSwitching\Tests;
 
 use user_switching;
 
-class SwitchingTest extends Test {
-
+final class SwitchingTest extends Test {
 	/**
 	 * @var int|false
 	 */
-	public $test_switching_user_id;
+	private $test_switching_user_id;
 
 	/**
 	 * @var int|false
 	 */
-	public $test_switching_old_user_id;
+	private $test_switching_old_user_id;
 
 	/**
 	 * @var int
 	 */
-	public $test_switching_auth_cookie_user_id;
+	private $test_switching_auth_cookie_user_id;
 
 	/**
 	 * @var bool
 	 */
-	public $test_switching_auth_cookie_remember;
+	private $test_switching_auth_cookie_remember;
 
-	public function _before() {
+	public function _before(): void {
 		parent::_before();
 
 		add_action( 'switch_to_user',         array( $this, '_action_switch_user' ), 10, 2 );
@@ -40,7 +37,7 @@ public function _before() {
 	/**
 	 * @covers \switch_to_user
 	 */
-	public function testSwitchUserAndBack() {
+	public function testSwitchUserAndBack(): void {
 		if ( is_multisite() ) {
 			$admin = self::$testers['super'];
 		} else {
@@ -145,7 +142,7 @@ public function testSwitchUserAndBack() {
 	 * @covers \switch_to_user
 	 * @covers \switch_off_user
 	 */
-	public function testSwitchOffAndBack() {
+	public function testSwitchOffAndBack(): void {
 		if ( is_multisite() ) {
 			$admin = self::$testers['super'];
 		} else {
@@ -200,7 +197,7 @@ public function testSwitchOffAndBack() {
 	/**
 	 * @covers \switch_to_user
 	 */
-	public function testSwitchToNonExistentUserFails() {
+	public function testSwitchToNonExistentUserFails(): void {
 		// Switch user
 		$user = switch_to_user( 0 );
 
@@ -208,10 +205,9 @@ public function testSwitchToNonExistentUserFails() {
 	}
 
 	/**
-	 * @testdox Current URL is detected correctly
 	 * @covers \user_switching::current_url
 	 */
-	public function testCurrentUrl() {
+	public function testCurrentUrl(): void {
 		$url = add_query_arg( 'foo', 'bar', home_url( 'baz' ) );
 		$this->go_to( $url );
 		self::assertSame( user_switching::current_url(), $url );
@@ -221,23 +217,20 @@ public function testCurrentUrl() {
 	 * @param int       $user_id
 	 * @param int|false $old_user_id
 	 */
-	public function _action_switch_user( $user_id, $old_user_id ) {
+	public function _action_switch_user( $user_id, $old_user_id ): void {
 		$this->test_switching_user_id = $user_id;
 		$this->test_switching_old_user_id = $old_user_id;
 	}
 
-	public function _action_switch_off( $old_user_id ) {
+	public function _action_switch_off( int $old_user_id ): void {
 		$this->test_switching_user_id = false;
 		$this->test_switching_old_user_id = $old_user_id;
 	}
 
-	/**
-	 * @return int
-	 */
-	public function _filter_auth_cookie_expiration( $length, $user_id, $remember ) {
+	public function _filter_auth_cookie_expiration( int $length, int $user_id, bool $remember ): int {
 		$this->test_switching_auth_cookie_user_id = $user_id;
 		$this->test_switching_auth_cookie_remember = $remember;
+
 		return $length;
 	}
-
 }
diff --git a/tests/phpstan/stubs.php b/tests/phpstan/stubs.php
index 3a58cd1..02c4188 100644
--- a/tests/phpstan/stubs.php
+++ b/tests/phpstan/stubs.php
@@ -41,7 +41,6 @@ function bp_get_button( array $args ) {}
 function buddypress() {}
 
 class BuddyPress {
-
 	/**
 	 * @var array<string, string>
 	 */
@@ -59,7 +58,6 @@ function bbp_get_user_id() {}
 function bbp_get_user_profile_url( int $user_id ) {}
 
 class WooCommerce {
-
 	/**
 	 * @var \WC_Session
 	 */