diff --git a/includes/Listeners/Cron.php b/includes/Listeners/Cron.php
index 7c89ea4..ba8bc47 100644
--- a/includes/Listeners/Cron.php
+++ b/includes/Listeners/Cron.php
@@ -2,6 +2,7 @@
 
 namespace NewfoldLabs\WP\Module\Data\Listeners;
 
+use NewfoldLabs\WP\Module\Data\EventManager;
 use NewfoldLabs\WP\Module\Data\Helpers\Plugin;
 
 /**
@@ -12,11 +13,13 @@ class Cron extends Listener {
 	/**
 	 * Register all required hooks for the listener category
 	 *
-	 * @return void
+	 * @see Listener::register_hooks()
+	 * @see EventManager::initialize_listeners()
 	 */
-	public function register_hooks() {
+	public function register_hooks(): void {
 
 		// Ensure there is a weekly option in the cron schedules
+		// phpcs:ignore WordPress.WP.CronInterval.ChangeDetected
 		add_filter( 'cron_schedules', array( $this, 'add_weekly_schedule' ) );
 
 		// Weekly cron hook
@@ -24,17 +27,21 @@ public function register_hooks() {
 
 		// Register the cron task
 		if ( ! wp_next_scheduled( 'nfd_data_cron' ) ) {
-			wp_schedule_event( time() + DAY_IN_SECONDS, 'weekly', 'nfd_data_cron' );
+			wp_schedule_event(
+				time() + constant( 'DAY_IN_SECONDS' ),
+				'weekly',
+				'nfd_data_cron'
+			);
 		}
-
 	}
 
 	/**
 	 * Cron event
 	 *
-	 * @return void
+	 * @hooked nfd_data_cron
+	 * @see Cron::register_hooks()
 	 */
-	public function update() {
+	public function update(): void {
 		$data = array(
 			'plugins' => Plugin::collect_installed(),
 		);
@@ -47,13 +54,16 @@ public function update() {
 	/**
 	 * Add the weekly option to cron schedules if it doesn't exist
 	 *
-	 * @param array $schedules List of cron schedule options
-	 * @return array
+	 * @hooked cron_schedules
+	 * @see wp_get_schedules()
+	 *
+	 * @param array<string, array{interval:int, display:string}> $schedules List of cron schedule options
+	 * @return array<string, array{interval:int, display:string}>
 	 */
-	public function add_weekly_schedule( $schedules ) {
-		if ( ! array_key_exists( 'weekly', $schedules ) || WEEK_IN_SECONDS !== $schedules['weekly']['interval'] ) {
+	public function add_weekly_schedule( $schedules ): array {
+		if ( ! array_key_exists( 'weekly', $schedules ) || constant( 'WEEK_IN_SECONDS' ) !== $schedules['weekly']['interval'] ) {
 			$schedules['weekly'] = array(
-				'interval' => WEEK_IN_SECONDS,
+				'interval' => constant( 'WEEK_IN_SECONDS' ),
 				'display'  => __( 'Once Weekly' ),
 			);
 		}
diff --git a/tests/phpunit/includes/Listeners/CronTest.php b/tests/phpunit/includes/Listeners/CronTest.php
new file mode 100644
index 0000000..30cf2ef
--- /dev/null
+++ b/tests/phpunit/includes/Listeners/CronTest.php
@@ -0,0 +1,159 @@
+<?php
+
+namespace NewfoldLabs\WP\Module\Data\Listeners;
+
+use WP_Mock;
+
+/**
+ * @coversDefaultClass \NewfoldLabs\WP\Module\Data\Listeners\Cron
+ */
+class CronTest extends \WP_Mock\Tools\TestCase {
+
+	public function setUp(): void
+	{
+		parent::setUp();
+
+		WP_Mock::passthruFunction('__');
+	}
+
+	/**
+	 * @covers ::register_hooks
+	 */
+	public function test_register_hooks(): void {
+		$event_manager = \Mockery::mock( \NewfoldLabs\WP\Module\Data\EventManager::class );
+
+		$sut = new Cron( $event_manager );
+
+		WP_Mock::expectFilterAdded( 'cron_schedules', array( $sut, 'add_weekly_schedule' ) );
+		WP_Mock::expectActionAdded( 'nfd_data_cron', array( $sut, 'update' ) );
+
+		WP_Mock::userFunction('wp_next_scheduled')
+			->with( 'nfd_data_cron' )
+			->once()->andReturnTrue();
+
+		$sut->register_hooks();
+
+		$this->assertConditionsMet();
+	}
+
+	/**
+	 * @covers ::register_hooks
+	 */
+	public function test_register_hooks_schedules_job_when_absent(): void {
+		$event_manager = \Mockery::mock( \NewfoldLabs\WP\Module\Data\EventManager::class );
+
+		$sut = new Cron( $event_manager );
+
+		WP_Mock::expectFilterAdded( 'cron_schedules', array( $sut, 'add_weekly_schedule' ) );
+		WP_Mock::expectActionAdded( 'nfd_data_cron', array( $sut, 'update' ) );
+
+		WP_Mock::userFunction('wp_next_scheduled')
+			->with( 'nfd_data_cron' )
+			->once()->andReturnFalse();
+
+		\Patchwork\redefine(
+			'constant',
+			function ( string $constant_name ) {
+				switch ($constant_name) {
+					case 'DAY_IN_SECONDS':
+						return 60 * 60 * 24;
+					default:
+						return \Patchwork\relay(func_get_args());
+				}
+			}
+		);
+
+		WP_Mock::userFunction('wp_schedule_event')
+			->with( \WP_Mock\Functions::type( 'int' ), 'weekly', 'nfd_data_cron' )
+			->once()->andReturnTrue();
+
+		$sut->register_hooks();
+
+		$this->assertConditionsMet();
+	}
+
+	/**
+	 * @covers ::update
+	 */
+	public function test_cron_job_main_function(): void {
+		$sut = \Mockery::mock( \NewfoldLabs\WP\Module\Data\Listeners\Cron::class )->makePartial();
+		$sut->shouldAllowMockingProtectedMethods();
+
+		WP_Mock::userFunction('get_plugins')
+			->once()->andReturn(array());
+
+		WP_Mock::userFunction('get_mu_plugins')
+			->once()->andReturn(array());
+
+		// WP_Mock::expectFilter('newfold_wp_data_module_cron_data_filter');
+
+		$sut->shouldReceive('push')
+			->once()
+			->with('cron', \Mockery::type('array'));
+
+		$sut->update();
+
+		$this->assertConditionsMet();
+	}
+
+	/**
+	 * @covers ::add_weekly_schedule
+	 */
+	public function test_add_weekly_schedule_to_wp_cron_schedules(): void {
+		$event_manager = \Mockery::mock( \NewfoldLabs\WP\Module\Data\EventManager::class );
+
+		$sut = new Cron( $event_manager );
+
+		\Patchwork\redefine(
+			'constant',
+			function ( string $constant_name ) {
+				switch ($constant_name) {
+					case 'WEEK_IN_SECONDS':
+						return 60 * 60 * 24 * 7;
+					default:
+						return \Patchwork\relay(func_get_args());
+				}
+			}
+		);
+
+		$result = $sut->add_weekly_schedule(array());
+
+		self::assertArrayHasKey('weekly', $result);
+		self::assertArrayHasKey('interval', $result['weekly']);
+		self::assertArrayHasKey('display', $result['weekly']);
+		self::assertEquals(604800, $result['weekly']['interval']);
+		self::assertEquals('Once Weekly', $result['weekly']['display']);
+	}
+
+	/**
+	 * @covers ::add_weekly_schedule
+	 */
+	public function test_fixes_weekly_schedule_in_wp_cron_schedules_if_value_is_wrong(): void {
+		$event_manager = \Mockery::mock( \NewfoldLabs\WP\Module\Data\EventManager::class );
+
+		$sut = new Cron( $event_manager );
+
+		\Patchwork\redefine(
+			'constant',
+			function ( string $constant_name ) {
+				switch ($constant_name) {
+					case 'WEEK_IN_SECONDS':
+						return 60 * 60 * 24 * 7;
+					default:
+						return \Patchwork\relay(func_get_args());
+				}
+			}
+		);
+
+		$result = $sut->add_weekly_schedule(
+			array(
+				'weekly' => array(
+					'interval' => 60 * 60 * 24, // Incorrect value.
+					'display' => 'Weekly'
+				)
+			)
+		);
+
+		self::assertEquals(604800, $result['weekly']['interval']);
+	}
+}