diff --git a/packages/php/email-editor/phpcs.xml b/packages/php/email-editor/phpcs.xml
index aea236529a..918a9146c4 100644
--- a/packages/php/email-editor/phpcs.xml
+++ b/packages/php/email-editor/phpcs.xml
@@ -11,6 +11,11 @@
 		<exclude-pattern>tests/*</exclude-pattern>
 	</rule>
 
+	<!-- Exclude bootstrap from the SeparateFunctionsFromOO.Mixed rule -->
+	<rule ref="Universal.Files.SeparateFunctionsFromOO.Mixed">
+		<exclude-pattern>tests/unit/_bootstrap.php</exclude-pattern>
+	</rule>
+
 	<!-- Skip the vendor directory -->
 	<exclude-pattern>vendor/*</exclude-pattern>
 </ruleset>
diff --git a/packages/php/email-editor/tests/unit/Container_Test.php b/packages/php/email-editor/tests/unit/Container_Test.php
index 4f5a212508..c3e52de5af 100644
--- a/packages/php/email-editor/tests/unit/Container_Test.php
+++ b/packages/php/email-editor/tests/unit/Container_Test.php
@@ -1,12 +1,24 @@
-<?php declare(strict_types = 1);
+<?php
+/**
+ * This file is part of the MailPoet plugin.
+ *
+ * @package MailPoet\EmailEditor
+ */
 
+declare(strict_types = 1);
 namespace MailPoet\EmailEditor;
 
 use Exception;
 use PHPUnit\Framework\TestCase;
 use stdClass;
 
+/**
+ * Unit test for Container class.
+ */
 class Container_Test extends TestCase {
+	/**
+	 * Test if sets and gets service.
+	 */
 	public function testSetAndGetService(): void {
 		$container = new Container();
 
@@ -22,6 +34,9 @@ class Container_Test extends TestCase {
 		$this->assertInstanceOf( stdClass::class, $service );
 	}
 
+	/**
+	 * Test if sets and gets service with dependencies.
+	 */
 	public function testGetReturnsSameInstance(): void {
 		$container = new Container();
 
@@ -32,19 +47,22 @@ class Container_Test extends TestCase {
 			}
 		);
 
-		// Retrieve the service twice
+		// Retrieve the service twice.
 		$service1 = $container->get( 'singleton_service' );
 		$service2 = $container->get( 'singleton_service' );
 
-		// Check that both instances are the same
+		// Check that both instances are the same.
 		$this->assertSame( $service1, $service2 );
 	}
 
+	/**
+	 * Test if it throws exception for non-existing service.
+	 */
 	public function testExceptionForNonExistingService(): void {
-		// Create the container instance
+		// Create the container instance.
 		$container = new Container();
 
-		// Attempt to get a non-existing service should throw an exception
+		// Attempt to get a non-existing service should throw an exception.
 		$this->expectException( Exception::class );
 		$this->expectExceptionMessage( 'Service not found: non_existing_service' );
 
diff --git a/packages/php/email-editor/tests/unit/_bootstrap.php b/packages/php/email-editor/tests/unit/_bootstrap.php
index 3d470608fb..c853a6e15a 100644
--- a/packages/php/email-editor/tests/unit/_bootstrap.php
+++ b/packages/php/email-editor/tests/unit/_bootstrap.php
@@ -1,16 +1,41 @@
-<?php declare(strict_types = 1);
+<?php
+/**
+ * This file is part of the MailPoet plugin.
+ *
+ * @package MailPoet\EmailEditor
+ */
+
+declare(strict_types = 1);
 
 $console = new \Codeception\Lib\Console\Output( array() );
 
 if ( ! function_exists( 'esc_attr' ) ) {
+	/**
+	 * Mock esc_attr function.
+	 *
+	 * @param string $attr Attribute to escape.
+	 */
 	function esc_attr( $attr ) {
 		return $attr;
 	}
 }
 
+/**
+ * Base class for unit tests.
+ */
 abstract class MailPoetUnitTest extends \Codeception\TestCase\Test {
-	protected $runTestInSeparateProcess = false;
-	protected $preserveGlobalState      = false;
+	/**
+	 * Disable running tests in separate processes.
+	 *
+	 * @var bool
+	 */
+	protected $runTestInSeparateProcess = false; // phpcs:ignore WordPress.NamingConventions.ValidVariableName.PropertyNotSnakeCase
+	/**
+	 * Disable preserving global state.
+	 *
+	 * @var bool
+	 */
+	protected $preserveGlobalState = false; // phpcs:ignore WordPress.NamingConventions.ValidVariableName.PropertyNotSnakeCase
 }
 
 require '_stubs.php';
diff --git a/packages/php/email-editor/tests/unit/_stubs.php b/packages/php/email-editor/tests/unit/_stubs.php
index 6e15f05300..4bebf9a2f8 100644
--- a/packages/php/email-editor/tests/unit/_stubs.php
+++ b/packages/php/email-editor/tests/unit/_stubs.php
@@ -1,14 +1,33 @@
-<?php declare(strict_types = 1);
-// phpcs:ignoreFile - We want to allow multiple classes etc.
+<?php
+/**
+ * This file is part of the MailPoet plugin.
+ *
+ * @package MailPoet\EmailEditor
+ */
 
-// Dummy WP classes
-if (!class_exists(\WP_Theme_JSON::class)) {
-  class WP_Theme_JSON {
-    public function get_data() {
-      return [];
-    }
-    public function get_settings() {
-      return [];
-    }
-  }
+declare(strict_types = 1);
+
+// Dummy WP classes.
+if ( ! class_exists( \WP_Theme_JSON::class ) ) {
+	/**
+	 * Class WP_Theme_JSON
+	 */
+	class WP_Theme_JSON {
+		/**
+		 * Get data.
+		 *
+		 * @return array
+		 */
+		public function get_data() {
+			return array();
+		}
+		/**
+		 * Get settings.
+		 *
+		 * @return array
+		 */
+		public function get_settings() {
+			return array();
+		}
+	}
 }