diff --git a/tests/unit/includes/blocks/omise-block-payments-test.php b/tests/unit/includes/blocks/omise-block-payments-test.php
new file mode 100644
index 00000000..d8d69f5b
--- /dev/null
+++ b/tests/unit/includes/blocks/omise-block-payments-test.php
@@ -0,0 +1,38 @@
+<?php
+
+use PHPUnit\Framework\TestCase;
+use Mockery\Adapter\Phpunit\MockeryPHPUnitIntegration;
+use Brain\Monkey;
+
+class Omise_Block_Payments_Test extends TestCase
+{
+    // Adds Mockery expectations to the PHPUnit assertions count.
+    use MockeryPHPUnitIntegration;
+
+    public $obj;
+
+    // @runInSeparateProcess
+    protected function setUp() : void
+    {
+        parent::setUp();
+        require_once __DIR__ . '/../../../../includes/blocks/omise-block-payments.php';
+    }
+
+    /**
+     * @test
+     */
+    public function class_is_initialized()
+    {
+        $this->expectNotToPerformAssertions();
+        $container = \Automattic\WooCommerce\Blocks\Package::container();
+
+        Monkey\Functions\expect('add_action')->andReturn(null);
+
+        $mock = $this->getMockBuilder(Omise_Block_Payments::class)
+            ->setConstructorArgs([$container])
+            ->onlyMethods(['add_payment_methods', 'initialize'])
+            ->getMock();
+
+        new Omise_Block_Payments($container);
+    }
+}
diff --git a/tests/unit/includes/blocks/omise-block-test.php b/tests/unit/includes/blocks/omise-block-test.php
index 4d8f7317..62a64478 100644
--- a/tests/unit/includes/blocks/omise-block-test.php
+++ b/tests/unit/includes/blocks/omise-block-test.php
@@ -2,7 +2,6 @@
 
 use PHPUnit\Framework\TestCase;
 use Mockery\Adapter\Phpunit\MockeryPHPUnitIntegration;
-use Brain\Monkey;
 
 class Omise_Block_Test extends TestCase
 {
diff --git a/tests/unit/includes/gateway/abstract-omise-payment-base-card-test.php b/tests/unit/includes/gateway/abstract-omise-payment-base-card-test.php
index 8e18ed10..fb965455 100644
--- a/tests/unit/includes/gateway/abstract-omise-payment-base-card-test.php
+++ b/tests/unit/includes/gateway/abstract-omise-payment-base-card-test.php
@@ -48,6 +48,7 @@ public function returnThis()
     protected function tearDown(): void
     {
         Mockery::close();
+        parent::tearDown();
     }
 
     public function getOrderMock($expectedAmount, $expectedCurrency)
diff --git a/tests/unit/includes/gateway/bootstrap-test-setup.php b/tests/unit/includes/gateway/bootstrap-test-setup.php
index c2220b1c..65f3e312 100644
--- a/tests/unit/includes/gateway/bootstrap-test-setup.php
+++ b/tests/unit/includes/gateway/bootstrap-test-setup.php
@@ -16,11 +16,6 @@ protected function setUp(): void
     {
         parent::setUp();
         Monkey\setUp();
-        Monkey\Functions\stubs( [
-            'wp_kses' => null,
-			'add_action' => null,
-		] );
-        Monkey\Functions\expect('plugins_url')->andReturn('');
     }
 
     /**
@@ -29,6 +24,7 @@ protected function setUp(): void
     protected function tearDown(): void
     {
         Monkey\tearDown();
+        Mockery::close();
         parent::tearDown();
     }
 
diff --git a/tests/unit/includes/gateway/class-omise-payment-alipayplus-hk-test.php b/tests/unit/includes/gateway/class-omise-payment-alipayplus-hk-test.php
index ddfa49b9..bb3b9fe9 100644
--- a/tests/unit/includes/gateway/class-omise-payment-alipayplus-hk-test.php
+++ b/tests/unit/includes/gateway/class-omise-payment-alipayplus-hk-test.php
@@ -1,5 +1,7 @@
 <?php
 
+use Brain\Monkey;
+
 require_once __DIR__ . '/class-omise-offsite-test.php';
 
 /**
@@ -11,6 +13,10 @@ protected function setUp(): void
     {
         $this->sourceType = 'alipay_hk';
         parent::setUp();
+
+        Monkey\Functions\expect('wp_kses');
+        Monkey\Functions\expect('wc_get_user_agent')->andReturn('Chrome Web');
+
         require_once __DIR__ . '/../../../../includes/gateway/class-omise-payment-alipayplus.php';
 
         if (!function_exists('wc_get_user_agent')) {
diff --git a/tests/unit/includes/gateway/class-omise-payment-alipayplus-kakaopay-test.php b/tests/unit/includes/gateway/class-omise-payment-alipayplus-kakaopay-test.php
index 2a938dff..31583132 100644
--- a/tests/unit/includes/gateway/class-omise-payment-alipayplus-kakaopay-test.php
+++ b/tests/unit/includes/gateway/class-omise-payment-alipayplus-kakaopay-test.php
@@ -1,5 +1,7 @@
 <?php
 
+use Brain\Monkey;
+
 require_once __DIR__ . '/class-omise-offsite-test.php';
 
 /**
@@ -11,6 +13,7 @@ protected function setUp(): void
     {
         $this->sourceType = 'kakaopay';
         parent::setUp();
+        Monkey\Functions\expect('wp_kses');
         require_once __DIR__ . '/../../../../includes/gateway/class-omise-payment-alipayplus.php';
     }
 
diff --git a/tests/unit/includes/gateway/class-omise-payment-atome-test.php b/tests/unit/includes/gateway/class-omise-payment-atome-test.php
index 0dc8af70..756b8ed0 100644
--- a/tests/unit/includes/gateway/class-omise-payment-atome-test.php
+++ b/tests/unit/includes/gateway/class-omise-payment-atome-test.php
@@ -13,16 +13,13 @@ protected function setUp(): void
         require_once __DIR__ . '/../../../../includes/gateway/class-omise-payment-atome.php';
 
         Monkey\Functions\expect('wp_enqueue_script');
+        Monkey\Functions\expect('wp_kses');
+        Monkey\Functions\expect('plugins_url');
 
         // dummy version
         if (!defined('WC_VERSION')) {
             define('WC_VERSION', '1.0.0');
         }
-
-        Brain\Monkey\setUp();
-        Brain\Monkey\Functions\stubs( [
-            'wp_kses' => null,
-		] );
     }
 
     public function testGetChargeRequest()
@@ -47,6 +44,7 @@ public function testGetChargeRequest()
 
     public function testCharge()
     {
+        Monkey\Functions\expect('add_action');
         $_POST['omise_atome_phone_default'] = true;
         $obj = new Omise_Payment_Atome();
         $this->getChargeTest($obj);
diff --git a/tests/unit/includes/gateway/class-omise-payment-creditcard-test.php b/tests/unit/includes/gateway/class-omise-payment-creditcard-test.php
index 18d87453..a4869a08 100644
--- a/tests/unit/includes/gateway/class-omise-payment-creditcard-test.php
+++ b/tests/unit/includes/gateway/class-omise-payment-creditcard-test.php
@@ -10,7 +10,6 @@ class Omise_Payment_CreditCard_Test extends TestCase
     protected function setUp(): void
     {
         parent::setUp();
-        Monkey\setUp();
 
         $this->omisePaymentMock = Mockery::mock('overload:Omise_Payment');
         $this->omisePaymentMock->shouldReceive('init_settings');
@@ -39,6 +38,7 @@ protected function setUp(): void
             define('WC_VERSION', '1.0.0');
         }
 
+        Monkey\Functions\expect('add_action')->andReturn(null);
         Monkey\Functions\expect('wp_enqueue_script');
         Monkey\Functions\expect('wp_kses')
             ->times(3)
@@ -56,6 +56,7 @@ protected function tearDown(): void
     {
         Monkey\tearDown();
         Mockery::close();
+        parent::tearDown();
     }
 
     /**
diff --git a/tests/unit/includes/gateway/class-omise-payment-duitnow-obw-test.php b/tests/unit/includes/gateway/class-omise-payment-duitnow-obw-test.php
index 504ed4e6..270f8d4f 100644
--- a/tests/unit/includes/gateway/class-omise-payment-duitnow-obw-test.php
+++ b/tests/unit/includes/gateway/class-omise-payment-duitnow-obw-test.php
@@ -1,5 +1,7 @@
 <?php
 
+use Brain\Monkey;
+
 require_once __DIR__ . '/class-omise-offsite-test.php';
 
 class Omise_Payment_DuitNow_OBW_Test extends Omise_Offsite_Test
@@ -10,6 +12,7 @@ protected function setUp(): void
     {
         $this->sourceType = 'duitnow_obw';
         parent::setUp();
+        Monkey\Functions\expect('add_action');
         $this->omise_capability_mock = Mockery::mock('alias:Omise_Capabilities');
         require_once __DIR__ . '/../../../../includes/gateway/class-omise-payment-duitnow-obw.php';
     }
diff --git a/tests/unit/includes/gateway/class-omise-payment-fpx-test.php b/tests/unit/includes/gateway/class-omise-payment-fpx-test.php
index b2e03afd..c6b8d229 100644
--- a/tests/unit/includes/gateway/class-omise-payment-fpx-test.php
+++ b/tests/unit/includes/gateway/class-omise-payment-fpx-test.php
@@ -1,5 +1,7 @@
 <?php
 
+use Brain\Monkey;
+
 require_once __DIR__ . '/class-omise-offsite-test.php';
 
 class Omise_Payment_FPX_Test extends Omise_Offsite_Test
@@ -8,6 +10,7 @@ protected function setUp(): void
     {
         $this->sourceType = 'fpx';
         parent::setUp();
+        Monkey\Functions\expect('add_action');
         require_once __DIR__ . '/../../../../includes/backends/class-omise-backend-fpx.php';
         require_once __DIR__ . '/../../../../includes/gateway/class-omise-payment-fpx.php';
     }
diff --git a/tests/unit/includes/gateway/class-omise-payment-googlepay-test.php b/tests/unit/includes/gateway/class-omise-payment-googlepay-test.php
index 7f236a08..3476b4e7 100644
--- a/tests/unit/includes/gateway/class-omise-payment-googlepay-test.php
+++ b/tests/unit/includes/gateway/class-omise-payment-googlepay-test.php
@@ -10,9 +10,10 @@ protected function setUp(): void
         parent::setUp();
         Monkey\setUp();
 
+        Monkey\Functions\expect('add_action')->andReturn(null);
         Monkey\Functions\expect('wp_kses')->andReturn(null);
         Monkey\Functions\expect('wp_enqueue_script');
-        Monkey\Functions\expect('plugins_url');
+        Monkey\Functions\expect('plugins_url')->andReturn('');
         Monkey\Functions\expect('get_woocommerce_currency')->andReturn('thb');
 
         // dummy version
@@ -48,6 +49,7 @@ protected function tearDown(): void
     {
         Monkey\tearDown();
         Mockery::close();
+        parent::tearDown();
     }
 
     /**
diff --git a/tests/unit/includes/gateway/class-omise-payment-installment-test.php b/tests/unit/includes/gateway/class-omise-payment-installment-test.php
index c7b82bfd..47f1d35a 100644
--- a/tests/unit/includes/gateway/class-omise-payment-installment-test.php
+++ b/tests/unit/includes/gateway/class-omise-payment-installment-test.php
@@ -10,13 +10,9 @@ protected function setUp(): void
     {
         $this->sourceType = 'installment_ktc';
         parent::setUp();
+        Monkey\Functions\expect('wp_kses');
+        Monkey\Functions\expect('add_action');
         require_once __DIR__ . '/../../../../includes/gateway/class-omise-payment-installment.php';
-
-        if (!function_exists('sanitize_text_field')) {
-            function sanitize_text_field() {
-                return 'Sanitized text';
-            }
-        }
     }
 
     /**
diff --git a/tests/unit/includes/gateway/class-omise-payment-internetbanking-test.php b/tests/unit/includes/gateway/class-omise-payment-internetbanking-test.php
index 5a0edca3..4196e2db 100644
--- a/tests/unit/includes/gateway/class-omise-payment-internetbanking-test.php
+++ b/tests/unit/includes/gateway/class-omise-payment-internetbanking-test.php
@@ -1,5 +1,7 @@
 <?php
 
+use Brain\Monkey;
+
 require_once __DIR__ . '/class-omise-offsite-test.php';
 
 class Omise_Payment_Internetbanking_Test extends Omise_Offsite_Test
@@ -8,6 +10,8 @@ protected function setUp(): void
     {
         $this->sourceType = 'fpx';
         parent::setUp();
+        Monkey\Functions\expect('wp_kses');
+        Monkey\Functions\expect('add_action');
         require_once __DIR__ . '/../../../../includes/gateway/class-omise-payment-internetbanking.php';
     }
 
diff --git a/tests/unit/includes/gateway/class-omise-payment-konbini-test.php b/tests/unit/includes/gateway/class-omise-payment-konbini-test.php
index 40d224d7..a6e0ef8a 100644
--- a/tests/unit/includes/gateway/class-omise-payment-konbini-test.php
+++ b/tests/unit/includes/gateway/class-omise-payment-konbini-test.php
@@ -1,5 +1,7 @@
 <?php
 
+use Brain\Monkey;
+
 class Omise_Payment_Konbini_Test extends Omise_Payment_Offline_Test
 {
     public $expectedAmount = 999999;
@@ -8,6 +10,9 @@ class Omise_Payment_Konbini_Test extends Omise_Payment_Offline_Test
     protected function setUp(): void
     {
         parent::setUp();
+        Monkey\Functions\expect('wp_kses');
+        Monkey\Functions\expect('add_action');
+
         // Mocking the parent class
         $offline = Mockery::mock('overload:Omise_Payment_Offline');
         $offline->shouldReceive('init_settings');
@@ -21,12 +26,6 @@ protected function setUp(): void
             ]);
 
         require_once __DIR__ . '/../../../../includes/gateway/class-omise-payment-konbini.php';
-
-        if (!function_exists('sanitize_text_field')) {
-            function sanitize_text_field() {
-                return 'Sanitized text';
-            }
-        }
     }
 
     public function testGetChargeRequest()
diff --git a/tests/unit/includes/gateway/class-omise-payment-mobilebanking-test.php b/tests/unit/includes/gateway/class-omise-payment-mobilebanking-test.php
index 70e145e7..e87f9e3a 100644
--- a/tests/unit/includes/gateway/class-omise-payment-mobilebanking-test.php
+++ b/tests/unit/includes/gateway/class-omise-payment-mobilebanking-test.php
@@ -1,5 +1,7 @@
 <?php
 
+use Brain\Monkey;
+
 require_once __DIR__ . '/class-omise-offsite-test.php';
 
 class Omise_Payment_Mobilebanking_Test extends Omise_Offsite_Test
@@ -13,9 +15,11 @@ protected function setUp(): void
 
     public function testCharge()
     {
-        Brain\Monkey\Functions\expect('wc_get_user_agent')
+        Monkey\Functions\expect('wc_get_user_agent')
 			->with('123')
 			->andReturn('Chrome Web');
+        Monkey\Functions\expect('wp_kses');
+        Monkey\Functions\expect('add_action');
         $_POST['omise-offsite'] = 'mobile_banking_bbl';
         $obj = new Omise_Payment_Mobilebanking();
         $this->getChargeTest($obj);
diff --git a/tests/unit/includes/gateway/class-omise-payment-ocbc-digital-test.php b/tests/unit/includes/gateway/class-omise-payment-ocbc-digital-test.php
index 300c68be..0e1c85f6 100644
--- a/tests/unit/includes/gateway/class-omise-payment-ocbc-digital-test.php
+++ b/tests/unit/includes/gateway/class-omise-payment-ocbc-digital-test.php
@@ -1,5 +1,6 @@
 <?php
 
+use Brain\Monkey;
 require_once __DIR__ . '/class-omise-offsite-test.php';
 
 class Omise_Payment_OCBC_Digital_Test extends Omise_Offsite_Test
@@ -10,6 +11,7 @@ protected function setUp(): void
     {
         $this->sourceType = 'mobile_banking_ocbc';
         parent::setUp();
+        Monkey\Functions\expect('add_action');
         require_once __DIR__ . '/../../../../includes/gateway/class-omise-payment-ocbc-digital.php';
         require_once __DIR__ . '/../../../../includes/classes/class-omise-image.php';
         $this->obj = new Omise_Payment_OCBC_Digital();
@@ -53,6 +55,7 @@ public function supportsIsCorrect()
      */
     public function getIconReturnsCorrectImageLink()
     {
+        Monkey\Functions\expect('plugins_url');
         $result = $this->obj->get_icon();
         $this->assertEquals(
             "<img src='/ocbc-digital.svg' class='Omise-Image' style='width: 30px; max-height: 30px;' alt='OCBC Digital' />",
diff --git a/tests/unit/includes/gateway/class-omise-payment-ocbc-pao-test.php b/tests/unit/includes/gateway/class-omise-payment-ocbc-pao-test.php
index 5af99d6e..d3a78890 100644
--- a/tests/unit/includes/gateway/class-omise-payment-ocbc-pao-test.php
+++ b/tests/unit/includes/gateway/class-omise-payment-ocbc-pao-test.php
@@ -1,5 +1,7 @@
 <?php
 
+use Brain\Monkey;
+
 require_once __DIR__ . '/class-omise-offsite-test.php';
 
 class Omise_Payment_OCBC_PAO_Test extends Omise_Offsite_Test
@@ -10,23 +12,17 @@ protected function setUp(): void
     {
         $this->sourceType = 'mobile_banking_ocbc';
         parent::setUp();
+        Monkey\Functions\expect('add_action');
         require_once __DIR__ . '/../../../../includes/gateway/class-omise-payment-ocbc-pao.php';
         $this->obj = new Omise_Payment_OCBC_PAO();
     }
 
-    protected function tearDown(): void
-    {
-        parent::tearDown();
-        // destroy object and clear memory
-        unset($this->obj);
-    }
-
     /**
      * @test
      */
     public function testCharge()
     {
-        Brain\Monkey\Functions\expect('wc_get_user_agent')
+        Monkey\Functions\expect('wc_get_user_agent')
 			->with('123')
 			->andReturn('Chrome Web');
         $this->getChargeTest($this->obj);
diff --git a/tests/unit/includes/gateway/class-omise-payment-promptpay-test.php b/tests/unit/includes/gateway/class-omise-payment-promptpay-test.php
index 64f5b828..d3dfd115 100644
--- a/tests/unit/includes/gateway/class-omise-payment-promptpay-test.php
+++ b/tests/unit/includes/gateway/class-omise-payment-promptpay-test.php
@@ -36,6 +36,9 @@ function admin_url() {}
     public function textExpiresAtFieldIsPassedToJavascript()
     {
         Monkey\Functions\expect('wp_enqueue_script');
+        Monkey\Functions\expect('wp_kses');
+        Monkey\Functions\expect('add_action');
+        Monkey\Functions\expect('plugins_url');
         $expiresAt = '2023-11-22T14:48:00.000Z';
 
         $this->mockFileGetContent->shouldReceive('get_contents')->once()->andReturn('<svg></svg>');
diff --git a/tests/unit/includes/gateway/class-omise-payment-rabbit-linepay-test.php b/tests/unit/includes/gateway/class-omise-payment-rabbit-linepay-test.php
index 737ba110..16fbcbbf 100644
--- a/tests/unit/includes/gateway/class-omise-payment-rabbit-linepay-test.php
+++ b/tests/unit/includes/gateway/class-omise-payment-rabbit-linepay-test.php
@@ -1,5 +1,7 @@
 <?php
 
+use Brain\Monkey;
+
 require_once __DIR__ . '/class-omise-offsite-test.php';
 
 class Omise_Payment_RabbitLinePay_Test extends Omise_Offsite_Test
@@ -10,17 +12,11 @@ protected function setUp(): void
     {
         $this->sourceType = 'mobile_banking_ocbc';
         parent::setUp();
+        Monkey\Functions\expect('add_action');
         require_once __DIR__ . '/../../../../includes/gateway/class-omise-payment-rabbit-linepay.php';
         $this->obj = new Omise_Payment_RabbitLinePay();
     }
 
-    protected function tearDown(): void
-    {
-        parent::tearDown();
-        // destroy object and clear memory
-        unset($this->obj);
-    }
-
     /**
      * @test
      */
diff --git a/tests/unit/includes/gateway/class-omise-payment-touch-n-go-test.php b/tests/unit/includes/gateway/class-omise-payment-touch-n-go-test.php
index 2ecaca2b..9683a57b 100644
--- a/tests/unit/includes/gateway/class-omise-payment-touch-n-go-test.php
+++ b/tests/unit/includes/gateway/class-omise-payment-touch-n-go-test.php
@@ -1,5 +1,7 @@
 <?php
 
+use Brain\Monkey;
+
 require_once __DIR__ . '/class-omise-offsite-test.php';
 
 class Omise_Payment_TouchNGo_Test extends Omise_Offsite_Test
@@ -16,6 +18,7 @@ protected function setUp(): void
      */
     public function restrictedCountriesHasRequiredCountries()
     {
+        Monkey\Functions\expect('add_action');
         $obj = new Omise_Payment_TouchNGo();
         $expectedCountries = ['SG', 'MY', 'TH'];
 
diff --git a/tests/unit/includes/gateway/class-omise-payment-truemoney-test.php b/tests/unit/includes/gateway/class-omise-payment-truemoney-test.php
index d18edfbc..943676cd 100644
--- a/tests/unit/includes/gateway/class-omise-payment-truemoney-test.php
+++ b/tests/unit/includes/gateway/class-omise-payment-truemoney-test.php
@@ -1,5 +1,7 @@
 <?php
 
+use Brain\Monkey;
+
 require_once __DIR__ . '/class-omise-offsite-test.php';
 
 class Omise_Payment_Truemoney_Test extends Omise_Offsite_Test
@@ -10,15 +12,17 @@ protected function setUp(): void
     {
         $this->sourceType = 'truemoney';
         parent::setUp();
-        Brain\Monkey\Functions\expect('is_admin')
+        Monkey\Functions\expect('is_admin')
 			->with('123')
 			->andReturn(true);
-		Brain\Monkey\Functions\expect('is_checkout')
+		Monkey\Functions\expect('is_checkout')
 			->with('123')
 			->andReturn(true);
-		Brain\Monkey\Functions\expect('is_wc_endpoint_url')
+		Monkey\Functions\expect('is_wc_endpoint_url')
 			->with('123')
 			->andReturn(true);
+        Monkey\Functions\expect('wp_kses');
+        Monkey\Functions\expect('add_action');
         require_once __DIR__ . '/../../../../includes/gateway/class-omise-payment-truemoney.php';
         $this->omise_capability_mock = Mockery::mock('alias:Omise_Capabilities');
     }
diff --git a/tests/unit/includes/gateway/class-omise-payment-wechat-pay-test.php b/tests/unit/includes/gateway/class-omise-payment-wechat-pay-test.php
index d9bafbbd..36b8dd64 100644
--- a/tests/unit/includes/gateway/class-omise-payment-wechat-pay-test.php
+++ b/tests/unit/includes/gateway/class-omise-payment-wechat-pay-test.php
@@ -1,5 +1,7 @@
 <?php
 
+use Brain\Monkey;
+
 require_once __DIR__ . '/class-omise-offsite-test.php';
 
 class Omise_Payment_Wechat_Pay_Test extends Omise_Offsite_Test
@@ -9,7 +11,7 @@ protected function setUp(): void
         parent::setUp();
         $this->sourceType = 'wechat_pay';
 
-        Brain\Monkey\Functions\stubs([
+        Monkey\Functions\stubs([
             'apply_filters' => function () {
                 return Omise_Image::get_image([
                     'file' => 'wechat_pay.svg',
@@ -18,6 +20,9 @@ protected function setUp(): void
             },
         ]);
 
+        Monkey\Functions\expect('wp_kses');
+        Monkey\Functions\expect('add_action');
+
         require_once __DIR__ . '/../../../../includes/libraries/omise-plugin/helpers/request.php';
         require_once __DIR__ . '/../../../../includes/gateway/class-omise-payment-wechat-pay.php';
     }
@@ -28,7 +33,6 @@ public function test_restricted_countries_field_has_required_countries()
         $expectedCountries = ['TH'];
 
         $this->assertEqualsCanonicalizing($expectedCountries, $obj->restricted_countries);
-        unset($expectedCountries);
     }
 
     public function test_charge()
@@ -39,6 +43,7 @@ public function test_charge()
 
     public function test_get_icon()
     {
+        Monkey\Functions\expect('plugins_url');
         $obj = new Omise_Payment_Wechat_Pay();
         $res = $obj->get_icon();
         $expected = "<img src='/wechat_pay.svg' class='Omise-Image' style='width: 30px; max-height: 30px;' alt='WeChat Pay' />";
diff --git a/tests/unit/omise-woocommerce-test.php b/tests/unit/omise-woocommerce-test.php
index 8a937649..37652f4a 100644
--- a/tests/unit/omise-woocommerce-test.php
+++ b/tests/unit/omise-woocommerce-test.php
@@ -1,6 +1,7 @@
 <?php
 
 use PHPUnit\Framework\TestCase;
+use Brain\Monkey;
 
 class Omise_Test extends TestCase
 {
@@ -11,16 +12,11 @@ class Omise_Test extends TestCase
 	 */
 	protected function setUp(): void
 	{
-		if (!function_exists('add_action')) {
-			function add_action()
-			{
-			}
-		}
-		if (!function_exists('do_action')) {
-			function do_action()
-			{
-			}
-		}
+		parent::setUp();
+		Monkey\setUp();
+		Monkey\Functions\expect('add_action')->andReturn(null);
+		Monkey\Functions\expect('do_action')->andReturn(null);
+
 		require_once __DIR__ . '/../../omise-woocommerce.php';
 		$this->model = Omise::instance();
 	}
@@ -30,7 +26,8 @@ function do_action()
 	 */
 	protected function tearDown(): void
 	{
-		Mockery::close();
+		Monkey\tearDown();
+		parent::tearDown();
 	}
 
 	/**