diff --git a/inc/Engine/CDN/RocketCDN/AdminPageSubscriber.php b/inc/Engine/CDN/RocketCDN/AdminPageSubscriber.php
index eeba4355b3..fe9319e19d 100644
--- a/inc/Engine/CDN/RocketCDN/AdminPageSubscriber.php
+++ b/inc/Engine/CDN/RocketCDN/AdminPageSubscriber.php
@@ -86,18 +86,21 @@ public function display_rocketcdn_status() {
 
 		$subscription_data = $this->api_client->get_subscription_data();
 
+		$container_class = '';
+		$status_class    = '';
+		$label           = '';
+		$status_text     = '';
+		$is_active       = false;
+
 		if ( 'running' === $subscription_data['subscription_status'] ) {
-			$label           = __( 'Next Billing Date', 'rocket' );
-			$status_class    = ' wpr-isValid';
-			$container_class = '';
-			$status_text     = date_i18n( get_option( 'date_format' ), strtotime( $subscription_data['subscription_next_date_update'] ) );
-			$is_active       = true;
+			$label        = __( 'Next Billing Date', 'rocket' );
+			$status_class = ' wpr-isValid';
+			$status_text  = date_i18n( get_option( 'date_format' ), strtotime( $subscription_data['subscription_next_date_update'] ) );
+			$is_active    = true;
 		} elseif ( 'cancelled' === $subscription_data['subscription_status'] ) {
-			$label           = '';
 			$status_class    = ' wpr-isInvalid';
 			$container_class = ' wpr-flex--egal';
 			$status_text     = __( 'No Subscription', 'rocket' );
-			$is_active       = false;
 		}
 
 		$data = [
diff --git a/inc/Engine/CDN/RocketCDN/views/cta-big.php b/inc/Engine/CDN/RocketCDN/views/cta-big.php
index cb5b3608d7..f5ccf86b32 100644
--- a/inc/Engine/CDN/RocketCDN/views/cta-big.php
+++ b/inc/Engine/CDN/RocketCDN/views/cta-big.php
@@ -15,6 +15,8 @@
  */
 
 defined( 'ABSPATH' ) || die( 'Cheatin’ uh?' );
+
+$data = isset( $data ) && is_array( $data ) ? $data : []; // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedVariableFound
 ?>
 <div class="wpr-rocketcdn-cta <?php echo esc_attr( $data['container_class'] ); ?>" id="wpr-rocketcdn-cta">
 	<?php if ( ! empty( $data['promotion_campaign'] ) ) : ?>
diff --git a/inc/Engine/CDN/RocketCDN/views/cta-small.php b/inc/Engine/CDN/RocketCDN/views/cta-small.php
index 93d8285592..dd5167561f 100644
--- a/inc/Engine/CDN/RocketCDN/views/cta-small.php
+++ b/inc/Engine/CDN/RocketCDN/views/cta-small.php
@@ -10,6 +10,8 @@
  */
 
 defined( 'ABSPATH' ) || die( 'Cheatin&#8217; uh?' );
+
+$data = isset( $data ) && is_array( $data ) ? $data : []; // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedVariableFound
 ?>
 <div class="wpr-rocketcdn-cta-small notice-alt notice-warning <?php echo esc_attr( $data['container_class'] ); ?>" id="wpr-rocketcdn-cta-small">
 	<div class="wpr-flex">
diff --git a/inc/Engine/CDN/RocketCDN/views/dashboard-status.php b/inc/Engine/CDN/RocketCDN/views/dashboard-status.php
index ac22d8a4c2..48ab3841eb 100644
--- a/inc/Engine/CDN/RocketCDN/views/dashboard-status.php
+++ b/inc/Engine/CDN/RocketCDN/views/dashboard-status.php
@@ -14,6 +14,7 @@
  * }
  */
 
+$data = isset( $data ) && is_array( $data ) ? $data : []; // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedVariableFound
 ?>
 <div class="wpr-optionHeader">
 	<h3 class="wpr-title2">RocketCDN</h3>
diff --git a/inc/Engine/Common/Database/Queries/AbstractQuery.php b/inc/Engine/Common/Database/Queries/AbstractQuery.php
index f74d93b1dc..29f15f599b 100644
--- a/inc/Engine/Common/Database/Queries/AbstractQuery.php
+++ b/inc/Engine/Common/Database/Queries/AbstractQuery.php
@@ -511,7 +511,7 @@ protected function table_exists(): bool {
 		$db = $this->get_db();
 
 		// Bail if no database interface is available.
-		if ( empty( $db ) ) {
+		if ( ! $db ) {
 			return false;
 		}
 
diff --git a/inc/Engine/Common/Database/Tables/AbstractTable.php b/inc/Engine/Common/Database/Tables/AbstractTable.php
index f8fd6a6885..283c9736cc 100644
--- a/inc/Engine/Common/Database/Tables/AbstractTable.php
+++ b/inc/Engine/Common/Database/Tables/AbstractTable.php
@@ -49,7 +49,7 @@ public function delete_old_rows() {
 		$db = $this->get_db();
 
 		// Bail if no database interface is available.
-		if ( empty( $db ) ) {
+		if ( ! $db ) {
 			return false;
 		}
 
@@ -89,7 +89,7 @@ public function get_old_rows(): array {
 		$db = $this->get_db();
 
 		// Bail if no database interface is available.
-		if ( empty( $db ) ) {
+		if ( ! $db ) {
 			return false;
 		}
 
@@ -113,7 +113,7 @@ public function remove_all_completed_rows() {
 		$db = $this->get_db();
 
 		// Bail if no database interface is available.
-		if ( empty( $db ) ) {
+		if ( ! $db ) {
 			return false;
 		}
 
diff --git a/inc/Engine/CriticalPath/APIClient.php b/inc/Engine/CriticalPath/APIClient.php
index ec285aa100..5112731297 100644
--- a/inc/Engine/CriticalPath/APIClient.php
+++ b/inc/Engine/CriticalPath/APIClient.php
@@ -108,7 +108,11 @@ private function get_response_success( $response_code, $response_data ) {
 		return (
 			200 === $response_code
 			&&
-			! empty( $response_data )
+			(
+				$response_data instanceof stdClass
+				&&
+				! empty( (array) $response_data )
+			)
 			&&
 			(
 				(
diff --git a/inc/Engine/License/views/promo-banner.php b/inc/Engine/License/views/promo-banner.php
index 78c42b396f..73bd727d9b 100644
--- a/inc/Engine/License/views/promo-banner.php
+++ b/inc/Engine/License/views/promo-banner.php
@@ -6,6 +6,8 @@
  */
 
 defined( 'ABSPATH' ) || exit;
+
+$data = isset( $data ) ? $data : []; // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedVariableFound
 ?>
 <div class="rocket-promo-banner" id="rocket-promo-banner">
 	<div>
diff --git a/inc/Engine/License/views/renewal-expired-banner-ocd-disabled.php b/inc/Engine/License/views/renewal-expired-banner-ocd-disabled.php
index 777030c6db..79995f55b6 100644
--- a/inc/Engine/License/views/renewal-expired-banner-ocd-disabled.php
+++ b/inc/Engine/License/views/renewal-expired-banner-ocd-disabled.php
@@ -6,6 +6,8 @@
  */
 
 defined( 'ABSPATH' ) || exit;
+
+$data = isset( $data ) ? $data : []; // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedVariableFound
 ?>
 <section class="rocket-renewal-expired-banner" id="rocket-renewal-banner">
 	<h3 class="rocket-expired-title"><?php esc_html_e( 'The Optimize CSS Delivery feature is disabled.', 'rocket' ); ?></h3>
diff --git a/inc/Engine/License/views/renewal-expired-banner-ocd.php b/inc/Engine/License/views/renewal-expired-banner-ocd.php
index 5aad300ed6..e8bb28a4ee 100644
--- a/inc/Engine/License/views/renewal-expired-banner-ocd.php
+++ b/inc/Engine/License/views/renewal-expired-banner-ocd.php
@@ -6,6 +6,8 @@
  */
 
 defined( 'ABSPATH' ) || exit;
+
+$data = isset( $data ) ? $data : []; // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedVariableFound
 ?>
 <section class="rocket-renewal-expired-banner" id="rocket-renewal-banner">
 	<h3 class="rocket-expired-title"><?php esc_html_e( 'You will soon lose access to some features.', 'rocket' ); ?></h3>
diff --git a/inc/Engine/License/views/renewal-expired-banner.php b/inc/Engine/License/views/renewal-expired-banner.php
index c3572769d2..eb294e4c03 100644
--- a/inc/Engine/License/views/renewal-expired-banner.php
+++ b/inc/Engine/License/views/renewal-expired-banner.php
@@ -6,6 +6,8 @@
  */
 
 defined( 'ABSPATH' ) || exit;
+
+$data = isset( $data ) ? $data : []; // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedVariableFound
 ?>
 <section class="rocket-renewal-expired-banner" id="rocket-renewal-banner">
 	<h3 class="rocket-expired-title"><?php esc_html_e( 'Your WP Rocket license is expired!', 'rocket' ); ?></h3>
diff --git a/inc/Engine/License/views/renewal-soon-banner.php b/inc/Engine/License/views/renewal-soon-banner.php
index 46bb3392d7..18a16985f5 100644
--- a/inc/Engine/License/views/renewal-soon-banner.php
+++ b/inc/Engine/License/views/renewal-soon-banner.php
@@ -6,6 +6,8 @@
  */
 
 defined( 'ABSPATH' ) || exit;
+
+$data = isset( $data ) ? $data : []; // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedVariableFound
 ?>
 <div class="rocket-renewal-banner">
 	<ul class="rocket-promo-countdown" id="rocket-renew-countdown">
diff --git a/inc/Engine/License/views/upgrade-popin.php b/inc/Engine/License/views/upgrade-popin.php
index 5a4ec990cd..af78aa4a51 100644
--- a/inc/Engine/License/views/upgrade-popin.php
+++ b/inc/Engine/License/views/upgrade-popin.php
@@ -6,6 +6,8 @@
  */
 
 defined( 'ABSPATH' ) || exit;
+
+$data = isset( $data ) ? $data : []; // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedVariableFound
 ?>
 <div class="wpr-Popin wpr-Popin-Upgrade">
 	<div class="wpr-Popin-header">
diff --git a/inc/Engine/Media/AboveTheFold/Database/Queries/AboveTheFold.php b/inc/Engine/Media/AboveTheFold/Database/Queries/AboveTheFold.php
index 74d539fa47..02230da8f7 100644
--- a/inc/Engine/Media/AboveTheFold/Database/Queries/AboveTheFold.php
+++ b/inc/Engine/Media/AboveTheFold/Database/Queries/AboveTheFold.php
@@ -85,7 +85,7 @@ public function make_job_completed( string $url, bool $is_mobile, array $data )
 		$db = $this->get_db();
 
 		// Bail if no database interface is available.
-		if ( empty( $db ) ) {
+		if ( ! $db ) {
 			return false;
 		}
 
@@ -115,7 +115,7 @@ public function delete_old_rows() {
 		$db = $this->get_db();
 
 		// Bail if no database interface is available.
-		if ( empty( $db ) ) {
+		if ( ! $db ) {
 			return false;
 		}
 
diff --git a/inc/Engine/Media/AboveTheFold/Frontend/Controller.php b/inc/Engine/Media/AboveTheFold/Frontend/Controller.php
index f5bb1dece3..26856608f5 100644
--- a/inc/Engine/Media/AboveTheFold/Frontend/Controller.php
+++ b/inc/Engine/Media/AboveTheFold/Frontend/Controller.php
@@ -147,7 +147,7 @@ private function set_fetchpriority( $lcp, string $html ): string {
 			'picture',
 		];
 
-		if ( empty( $lcp ) || empty( $lcp->type ) || ! in_array( $lcp->type, $allowed_types, true ) ) {
+		if ( empty( (array) $lcp ) || empty( $lcp->type ) || ! in_array( $lcp->type, $allowed_types, true ) ) {
 			return $html;
 		}
 
@@ -488,7 +488,7 @@ private function generate_source_tags( $lcp, $start_tag, $end_tag ) {
 			$link_attribute = ( substr_count( $source->srcset, ',' ) > 0 ) ? 'imagesrcset' : 'href';
 
 			// Append the source and media query to the tag string.
-			$tag .= $start_tag . $link_attribute . '="' . $source->srcset . '"' . ( $media ?? '' ) . $sizes . $end_tag;
+			$tag .= $start_tag . $link_attribute . '="' . $source->srcset . '"' . ( $media ) . $sizes . $end_tag;
 
 			// If a max-width is found in the source's media attribute, update the previous max-width.
 			if ( preg_match( '/\(max-width: (\d+(\.\d+)?)px\)/', $source->media, $matches ) ) {
diff --git a/inc/Engine/Media/ImageDimensions/ImageDimensions.php b/inc/Engine/Media/ImageDimensions/ImageDimensions.php
index 77e3832511..1a6f024299 100644
--- a/inc/Engine/Media/ImageDimensions/ImageDimensions.php
+++ b/inc/Engine/Media/ImageDimensions/ImageDimensions.php
@@ -208,10 +208,6 @@ private function is_external_file( $url ) {
 
 		$hosts = array_unique( $hosts );
 
-		if ( empty( $hosts ) ) {
-			return true;
-		}
-
 		// URL has domain and domain is part of the internal domains.
 		if ( ! empty( $file['host'] ) ) {
 			foreach ( $hosts as $host ) {
diff --git a/inc/Engine/Optimization/CSSTrait.php b/inc/Engine/Optimization/CSSTrait.php
index 58bbbf4641..3a90e18c1c 100644
--- a/inc/Engine/Optimization/CSSTrait.php
+++ b/inc/Engine/Optimization/CSSTrait.php
@@ -469,10 +469,6 @@ protected function is_external_path( $url ) {
 
 		$hosts = array_unique( $hosts );
 
-		if ( empty( $hosts ) ) {
-			return true;
-		}
-
 		// URL has domain and domain is part of the internal domains.
 		if ( ! empty( $file['host'] ) ) {
 			foreach ( $hosts as $host ) {
diff --git a/inc/Engine/Optimization/RUCSS/Controller/UsedCSS.php b/inc/Engine/Optimization/RUCSS/Controller/UsedCSS.php
index 9a8ba4a31a..27d40d8f53 100644
--- a/inc/Engine/Optimization/RUCSS/Controller/UsedCSS.php
+++ b/inc/Engine/Optimization/RUCSS/Controller/UsedCSS.php
@@ -499,6 +499,8 @@ private function add_used_fonts_preload( string $html, string $used_css ): strin
 
 			// Making sure the excluded fonts array isn't empty to avoid excluding all fonts.
 			if ( ! empty( $exclude_fonts_preload ) ) {
+				$exclude_fonts_preload = array_filter( $exclude_fonts_preload );
+
 				// Combine the array elements into a single string with | as a separator and returning a pattern.
 				$exclude_fonts_preload_pattern = implode(
 					'|',
diff --git a/inc/Engine/Optimization/RUCSS/Database/Queries/UsedCSS.php b/inc/Engine/Optimization/RUCSS/Database/Queries/UsedCSS.php
index 89ed6188bf..99e8a5087c 100644
--- a/inc/Engine/Optimization/RUCSS/Database/Queries/UsedCSS.php
+++ b/inc/Engine/Optimization/RUCSS/Database/Queries/UsedCSS.php
@@ -87,7 +87,7 @@ public function make_status_completed( string $url, bool $is_mobile, string $has
 		$db = $this->get_db();
 
 		// Bail if no database interface is available.
-		if ( empty( $db ) ) {
+		if ( ! $db ) {
 			return false;
 		}
 
diff --git a/inc/Engine/Optimization/UrlTrait.php b/inc/Engine/Optimization/UrlTrait.php
index 07e5b08c30..979c6db72a 100644
--- a/inc/Engine/Optimization/UrlTrait.php
+++ b/inc/Engine/Optimization/UrlTrait.php
@@ -51,10 +51,6 @@ private function is_external_file( $url ) {
 
 		$hosts = array_unique( $hosts );
 
-		if ( empty( $hosts ) ) {
-			return true;
-		}
-
 		// URL has domain and domain is part of the internal domains.
 		if ( ! empty( $file['host'] ) ) {
 			foreach ( $hosts as $host ) {
diff --git a/inc/Engine/Preload/Controller/PreloadUrl.php b/inc/Engine/Preload/Controller/PreloadUrl.php
index a085e0ad8c..7e8f41987c 100755
--- a/inc/Engine/Preload/Controller/PreloadUrl.php
+++ b/inc/Engine/Preload/Controller/PreloadUrl.php
@@ -61,6 +61,9 @@ public function __construct( Options_Data $options, Queue $queue, Cache $rocket_
 	 * @return void
 	 */
 	public function preload_url( string $url ) {
+		$start    = 0;
+		$duration = 0;
+
 		$is_mobile = $this->options->get( 'do_caching_mobile_files', false );
 
 		if ( $this->is_already_cached( $url ) && ( ! $is_mobile || $this->is_already_cached( $url, true ) ) ) {
diff --git a/inc/Engine/Preload/Database/Queries/Cache.php b/inc/Engine/Preload/Database/Queries/Cache.php
index 82d06fb935..c03aa909e6 100644
--- a/inc/Engine/Preload/Database/Queries/Cache.php
+++ b/inc/Engine/Preload/Database/Queries/Cache.php
@@ -303,7 +303,7 @@ public function get_old_cache( float $delay = 1, string $unit = 'month' ): array
 		$db = $this->get_db();
 
 		// Bail if no database interface is available.
-		if ( empty( $db ) ) {
+		if ( ! $db ) {
 			return [];
 		}
 
@@ -473,7 +473,7 @@ public function revert_old_in_progress() {
 		$db = $this->get_db();
 
 		// Bail if no database interface is available.
-		if ( empty( $db ) ) {
+		if ( ! $db ) {
 			return false;
 		}
 
@@ -489,7 +489,7 @@ public function revert_old_failed() {
 		$db = $this->get_db();
 
 		// Bail if no database interface is available.
-		if ( empty( $db ) ) {
+		if ( ! $db ) {
 			return false;
 		}
 
@@ -505,7 +505,7 @@ public function set_all_to_pending() {
 		$db = $this->get_db();
 
 		// Bail if no database interface is available.
-		if ( empty( $db ) ) {
+		if ( ! $db ) {
 			return false;
 		}
 
@@ -568,7 +568,7 @@ public function remove_all() {
 		$db = $this->get_db();
 
 		// Bail if no database interface is available.
-		if ( empty( $db ) ) {
+		if ( ! $db ) {
 			return false;
 		}
 
@@ -603,7 +603,7 @@ public function unlock_all() {
 		$db = $this->get_db();
 
 		// Bail if no database interface is available.
-		if ( empty( $db ) ) {
+		if ( ! $db ) {
 			return false;
 		}
 
diff --git a/inc/ThirdParty/Plugins/Optimization/AMP.php b/inc/ThirdParty/Plugins/Optimization/AMP.php
index 5b66ae55fb..2a27e9ae3f 100644
--- a/inc/ThirdParty/Plugins/Optimization/AMP.php
+++ b/inc/ThirdParty/Plugins/Optimization/AMP.php
@@ -126,7 +126,7 @@ public function disable_options_on_amp() {
 
 		global $wp_filter;
 
-		remove_filter( 'wp_resource_hints', 'rocket_dns_prefetch', 10, 2 );
+		remove_filter( 'wp_resource_hints', 'rocket_dns_prefetch', 10 );
 		add_filter( 'do_rocket_lazyload', '__return_false' );
 		add_filter( 'do_rocket_lazyload_iframes', '__return_false' );
 		add_filter( 'pre_get_rocket_option_async_css', '__return_false' );
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index 71ae4fda0b..db347384e3 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -1,7 +1,7 @@
 includes:
 	- phar://phpstan.phar/conf/bleedingEdge.neon
 parameters:
-	level: 0
+	level: 1
 	inferPrivatePropertyTypeFromConstructor: true
 	paths:
 		# Test only the new architecture for now.
@@ -13,6 +13,8 @@ parameters:
 	bootstrapFiles:
 		# Must be first
 		- %currentWorkingDirectory%/inc/functions/options.php
+		# PHPStan bootstrap
+		- %currentWorkingDirectory%/tests/phpstan/phpstan-bootstrap.php
 		# Procedural code
 		- %currentWorkingDirectory%/inc/constants.php
 		- %currentWorkingDirectory%/inc/common/purge.php
@@ -41,6 +43,7 @@ parameters:
 		- %currentWorkingDirectory%/inc/admin/options.php
 		- %currentWorkingDirectory%/vendor/php-stubs/wordpress-stubs/wordpress-stubs.php
 		- %currentWorkingDirectory%/vendor/php-stubs/wordpress-tests-stubs/wordpress-tests-stubs.php
+		- %currentWorkingDirectory%/wp-rocket.php
 	excludePaths:
 		 - %currentWorkingDirectory%/inc/vendors/
 		 # These need plugin stubs!
diff --git a/tests/Fixtures/inc/ThirdParty/Hostings/LiteSpeed/override_header_functions.php b/tests/Fixtures/inc/ThirdParty/Hostings/LiteSpeed/override_header_functions.php
index 0adabf1196..4d47890a17 100644
--- a/tests/Fixtures/inc/ThirdParty/Hostings/LiteSpeed/override_header_functions.php
+++ b/tests/Fixtures/inc/ThirdParty/Hostings/LiteSpeed/override_header_functions.php
@@ -10,7 +10,7 @@ function headers_sent()
 	return false;
 }
 
-function header($string)
+function header($string, $replace)
 {
 	if (  in_array( $string , HeaderCollector::$headers, true ) ) {
 		return;
diff --git a/tests/Fixtures/inc/ThirdParty/Plugins/SEO/SEOPress/fixtures.php b/tests/Fixtures/inc/ThirdParty/Plugins/SEO/SEOPress/fixtures.php
index d66b82443c..f4af1fd2a4 100644
--- a/tests/Fixtures/inc/ThirdParty/Plugins/SEO/SEOPress/fixtures.php
+++ b/tests/Fixtures/inc/ThirdParty/Plugins/SEO/SEOPress/fixtures.php
@@ -1,6 +1,6 @@
 <?php
 if(! function_exists('seopress_get_toggle_option')) {
-	function seopress_get_toggle_option() {
+	function seopress_get_toggle_option( $name ) {
 		return '1';
 	}
 }
diff --git a/tests/Integration/inc/Engine/CriticalPath/CriticalCSSSubscriber/deleteCpcss.php b/tests/Integration/inc/Engine/CriticalPath/CriticalCSSSubscriber/deleteCpcss.php
index 0e409b656c..262da98bb1 100644
--- a/tests/Integration/inc/Engine/CriticalPath/CriticalCSSSubscriber/deleteCpcss.php
+++ b/tests/Integration/inc/Engine/CriticalPath/CriticalCSSSubscriber/deleteCpcss.php
@@ -67,6 +67,8 @@ public function testShouldDoExpected( $config, $expected ) {
 		$this->filesystem->put_contents( $item_path, '.cpcss { color: red; }');
 		$this->assertTrue( $this->filesystem->exists( $item_path ) );
 
+		$mobile_item_path = '';
+
 		if ( $this->async_css_mobile ) {
 			$mobile_item_path = 'wp-content/cache/critical-css/1/posts' . DIRECTORY_SEPARATOR . "{$post_type}-" . self::$post_id . "-mobile.css";
 			$this->filesystem->put_contents( $mobile_item_path, '.cpcss-mobile { color: red; }');
diff --git a/tests/Integration/inc/Engine/CriticalPath/ProcessorService/processGenerate.php b/tests/Integration/inc/Engine/CriticalPath/ProcessorService/processGenerate.php
index 0a9ad2c3c9..862b0f61d1 100644
--- a/tests/Integration/inc/Engine/CriticalPath/ProcessorService/processGenerate.php
+++ b/tests/Integration/inc/Engine/CriticalPath/ProcessorService/processGenerate.php
@@ -138,7 +138,7 @@ public function testShouldDoExpected( $config, $expected ) {
 			}
 		}
 
-		if ( isset( $save_cpcss ) && is_wp_error( $save_cpcss ) ) {
+		if ( is_wp_error( $save_cpcss ) ) {
 			$this->filesystem->chmod( 'wp-content/cache/critical-css/1/', 0444 );
 		}
 
diff --git a/tests/Integration/inc/Engine/Media/ImageDimensions/Subscriber/specifyImageDimensions.php b/tests/Integration/inc/Engine/Media/ImageDimensions/Subscriber/specifyImageDimensions.php
index 1269bfbe06..aec2370c49 100644
--- a/tests/Integration/inc/Engine/Media/ImageDimensions/Subscriber/specifyImageDimensions.php
+++ b/tests/Integration/inc/Engine/Media/ImageDimensions/Subscriber/specifyImageDimensions.php
@@ -28,7 +28,7 @@ public function tear_down() {
 			remove_filter( 'rocket_specify_image_dimensions', [$this, 'filter_rocket_specify_image_dimensions'] );
 		}
 
-		if ( isset( $config['rocket_specify_dimension_skip_pictures_filter'] ) ){
+		if ( isset( $this->config_data['rocket_specify_dimension_skip_pictures_filter'] ) ){
 			remove_filter( 'rocket_specify_dimension_skip_pictures', [$this, 'filter_rocket_specify_dimension_skip_pictures'] );
 		}
 
diff --git a/tests/Integration/inc/Engine/Optimization/DelayJS/Subscriber/delayJs.php b/tests/Integration/inc/Engine/Optimization/DelayJS/Subscriber/delayJs.php
index ca19af9e4b..52ef757140 100644
--- a/tests/Integration/inc/Engine/Optimization/DelayJS/Subscriber/delayJs.php
+++ b/tests/Integration/inc/Engine/Optimization/DelayJS/Subscriber/delayJs.php
@@ -40,7 +40,7 @@ public function tear_down() {
 		delete_transient( 'wpr_dynamic_lists' );
 
 		if ( isset( $this->post->ID ) ) {
-			delete_post_meta( $this->post->ID, '_rocket_exclude_delay_js', 1, true );
+			delete_post_meta( $this->post->ID, '_rocket_exclude_delay_js', 1 );
 		}
 
 		$this->restoreWpHook( 'rocket_buffer' );
diff --git a/tests/Integration/inc/Engine/Optimization/RUCSS/Frontend/Subscriber/maybeDisablePreloadFonts.php b/tests/Integration/inc/Engine/Optimization/RUCSS/Frontend/Subscriber/maybeDisablePreloadFonts.php
index dc04c5b875..5b1c3fb795 100644
--- a/tests/Integration/inc/Engine/Optimization/RUCSS/Frontend/Subscriber/maybeDisablePreloadFonts.php
+++ b/tests/Integration/inc/Engine/Optimization/RUCSS/Frontend/Subscriber/maybeDisablePreloadFonts.php
@@ -30,7 +30,7 @@ public function tear_down() {
 		remove_filter( 'pre_get_rocket_option_remove_unused_css', [ $this, 'rucss' ] );
 
 		if ( isset( $this->post->ID ) ) {
-			delete_post_meta( $this->post->ID, '_rocket_exclude_remove_unused_css', 1, true );
+			delete_post_meta( $this->post->ID, '_rocket_exclude_remove_unused_css', 1 );
 		}
 
 		remove_filter( 'pre_option_wp_rocket_prewarmup_stats', [ $this, 'return_prewarmup_stats' ] );
diff --git a/tests/Unit/inc/Engine/Cache/Purge/purgePostTermsUrls.php b/tests/Unit/inc/Engine/Cache/Purge/purgePostTermsUrls.php
index b95b242715..795ce442ab 100644
--- a/tests/Unit/inc/Engine/Cache/Purge/purgePostTermsUrls.php
+++ b/tests/Unit/inc/Engine/Cache/Purge/purgePostTermsUrls.php
@@ -120,7 +120,7 @@ public function testShouldReturnExpectedUrls( $post_data, $terms, $expected ) {
 				}
 			}
 		}
-		Filters\expectApplied( 'rocket_post_terms_urls', $expected )->once();
+		Filters\expectApplied( 'rocket_post_terms_urls' )->once();
 
 		$this->stubWpParseUrl();
 
diff --git a/tests/Unit/inc/Engine/Common/JobManager/Strategy/Strategies/JobSetFail/execute.php b/tests/Unit/inc/Engine/Common/JobManager/Strategy/Strategies/JobSetFail/execute.php
index 6f4f6862c0..fe43ed9e04 100644
--- a/tests/Unit/inc/Engine/Common/JobManager/Strategy/Strategies/JobSetFail/execute.php
+++ b/tests/Unit/inc/Engine/Common/JobManager/Strategy/Strategies/JobSetFail/execute.php
@@ -34,6 +34,10 @@ public function testShouldBehaveAsExpected( $config, $expected )
 		} else {
 			$row_details = null;
 		}
+		$job_details = [
+			'code' => '',
+			'message' => '',
+		];
 		if ( isset( $config['job_details'] ) ) {
 			$job_details = $config['job_details'];
 		}
diff --git a/tests/Unit/inc/Engine/CriticalPath/Admin/Admin/enqueueAdminCpcssHeartbeatScript.php b/tests/Unit/inc/Engine/CriticalPath/Admin/Admin/enqueueAdminCpcssHeartbeatScript.php
index 781ddd90f0..368c8661d0 100644
--- a/tests/Unit/inc/Engine/CriticalPath/Admin/Admin/enqueueAdminCpcssHeartbeatScript.php
+++ b/tests/Unit/inc/Engine/CriticalPath/Admin/Admin/enqueueAdminCpcssHeartbeatScript.php
@@ -44,7 +44,7 @@ public function testShouldEnqueueAdminScript( $config, $expected ) {
 				->andReturn( $config['options']['async_css'] );
 
 		if ( $expected ) {
-			$this->assertExpected( $config );
+			$this->assertExpected();
 		} else {
 			$this->assertNotExpected();
 		}
diff --git a/tests/Unit/inc/ThirdParty/Plugins/Optimization/AMP/disableOptionsOnAmp.php b/tests/Unit/inc/ThirdParty/Plugins/Optimization/AMP/disableOptionsOnAmp.php
index c822fa3071..411690687a 100644
--- a/tests/Unit/inc/ThirdParty/Plugins/Optimization/AMP/disableOptionsOnAmp.php
+++ b/tests/Unit/inc/ThirdParty/Plugins/Optimization/AMP/disableOptionsOnAmp.php
@@ -58,7 +58,7 @@ public function testShouldDoExpected( $config, $expected ) {
 			// Check the hooks before invoking the method.
 			$this->assertSame(
 				10,
-				has_filter( 'wp_resource_hints', 'rocket_dns_prefetch', 10, 2 )
+				has_filter( 'wp_resource_hints', 'rocket_dns_prefetch' )
 			);
 			$this->assertFalse( has_filter( 'do_rocket_lazyload', '__return_false' ) );
 			$this->assertFalse( has_filter( 'do_rocket_lazyload_iframes', '__return_false' ) );
@@ -70,7 +70,7 @@ public function testShouldDoExpected( $config, $expected ) {
 
 			$this->assertSame(
 				PHP_INT_MAX,
-				has_filter( 'wp_calculate_image_srcset', 'rocket_protocol_rewrite_srcset', PHP_INT_MAX )
+				has_filter( 'wp_calculate_image_srcset', 'rocket_protocol_rewrite_srcset' )
 			);
 			$this->assertFalse( has_filter( 'rocket_buffer', [ $this->cdn_subscriber, 'rewrite' ] ) );
 			$this->assertFalse( has_filter( 'rocket_buffer', [ $this->cdn_subscriber, 'rewrite_srcset' ] ) );
@@ -85,7 +85,7 @@ public function testShouldDoExpected( $config, $expected ) {
 
 		if ( ! $expected[ 'bailout' ] ) {
 			// Check the hooks after invoking the method.
-			$this->assertFalse( has_filter( 'wp_resource_hints', 'rocket_dns_prefetch', 10, 2 ) );
+			$this->assertFalse( has_filter( 'wp_resource_hints', 'rocket_dns_prefetch' ) );
 			$this->assertSame(
 				10,
 				has_filter( 'do_rocket_lazyload', '__return_false' )
diff --git a/tests/Unit/inc/functions/rocketRrmdir.php b/tests/Unit/inc/functions/rocketRrmdir.php
index dc88aea255..40a9f94db9 100644
--- a/tests/Unit/inc/functions/rocketRrmdir.php
+++ b/tests/Unit/inc/functions/rocketRrmdir.php
@@ -31,7 +31,7 @@ public function testShouldRecursivelyRemoveFilesAndDirectories( $to_delete, $to_
 		rocket_rrmdir( $to_delete, $to_preserve );
 
 		$dump_results = isset( $expected['dump_results'] );
-		$this->checkEntriesDeleted( $expected['removed'], $dump_results );
+		$this->checkEntriesDeleted( $expected['removed'] );
 		$this->checkShouldNotDeleteEntries( $dump_results );
 	}
 }
diff --git a/tests/phpstan/phpstan-bootstrap.php b/tests/phpstan/phpstan-bootstrap.php
new file mode 100644
index 0000000000..0577e85f32
--- /dev/null
+++ b/tests/phpstan/phpstan-bootstrap.php
@@ -0,0 +1,10 @@
+<?php
+	define( 'WP_ROCKET_PLUGIN_NAME', 'WP Rocket' );
+	define( 'WP_ROCKET_PLUGIN_SLUG', 'wp-rocket' );
+
+	define( 'AUTH_COOKIE', 'default_auth_cookie' );
+	define( 'LOGGED_IN_COOKIE', 'default_logged_in_cookie' );
+	define( 'PASS_COOKIE', 'default_pass_cookie' );
+	define( 'SECURE_AUTH_COOKIE', 'default_secure_auth_cookie' );
+	define( 'USER_COOKIE', 'default_user_cookie' );
+	define( 'WP_STACK_CDN_DOMAIN', '' );