diff --git a/tests/PHPUnit/ModularTestCase.php b/tests/PHPUnit/ModularTestCase.php
new file mode 100644
index 000000000..be813085f
--- /dev/null
+++ b/tests/PHPUnit/ModularTestCase.php
@@ -0,0 +1,70 @@
+<?php
+declare(strict_types=1);
+
+namespace WooCommerce\PayPalCommerce;
+
+use Dhii\Container\CompositeCachingServiceProvider;
+use Dhii\Container\DelegatingContainer;
+use Dhii\Container\ServiceProvider;
+use Mockery\Adapter\Phpunit\MockeryPHPUnitIntegration;
+use Psr\Container\ContainerInterface;
+use function Brain\Monkey\Functions\when;
+
+class ModularTestCase extends TestCase
+{
+	use MockeryPHPUnitIntegration;
+
+    public function setUp(): void
+    {
+        parent::setUp();
+
+        when('get_option')->justReturn(null);
+        when('plugins_url')->returnArg();
+        when('plugin_dir_path')->alias(function ($file) { return trailingslashit(dirname($file)); });
+        when('get_current_blog_id')->justReturn(42);
+        when('get_site_url')->justReturn('example.com');
+        when('get_bloginfo')->justReturn('My Shop');
+        when('wc_get_base_location')->justReturn(['country' => 'US']);
+        when('get_woocommerce_currency')->justReturn('USD');
+        when('WC')->justReturn((object) [
+        	'session' => null,
+		]);
+
+		global $wpdb;
+		$wpdb = \Mockery::mock(\stdClass::class);
+		$wpdb->shouldReceive('get_var')->andReturn(null);
+		$wpdb->shouldReceive('prepare')->andReturn(null);
+		$wpdb->posts = '';
+		$wpdb->postmeta = '';
+
+		!defined('PAYPAL_API_URL') && define('PAYPAL_API_URL', 'https://api.paypal.com');
+		!defined('PAYPAL_SANDBOX_API_URL') && define('PAYPAL_SANDBOX_API_URL', 'https://api.sandbox.paypal.com');
+		!defined('PAYPAL_INTEGRATION_DATE') && define('PAYPAL_INTEGRATION_DATE', '2020-10-15');
+
+		!defined('PPCP_FLAG_SUBSCRIPTION') && define('PPCP_FLAG_SUBSCRIPTION', true);
+
+		!defined('CONNECT_WOO_CLIENT_ID') && define('CONNECT_WOO_CLIENT_ID', 'woo-id');
+		!defined('CONNECT_WOO_SANDBOX_CLIENT_ID') && define('CONNECT_WOO_SANDBOX_CLIENT_ID', 'woo-id2');
+		!defined('CONNECT_WOO_MERCHANT_ID') && define('CONNECT_WOO_MERCHANT_ID', 'merchant-id');
+		!defined('CONNECT_WOO_SANDBOX_MERCHANT_ID') && define('CONNECT_WOO_SANDBOX_MERCHANT_ID', 'merchant-id2');
+		!defined('CONNECT_WOO_URL') && define('CONNECT_WOO_URL', 'https://connect.woocommerce.com/ppc');
+		!defined('CONNECT_WOO_SANDBOX_URL') && define('CONNECT_WOO_SANDBOX_URL', 'https://connect.woocommerce.com/ppcsandbox');
+    }
+
+    /**
+     * @param array<string, callable> $overriddenServices
+     * @return ContainerInterface
+     */
+    protected function bootstrapModule(array $overriddenServices = []): ContainerInterface
+    {
+        $overridingContainer = new DelegatingContainer(new CompositeCachingServiceProvider([
+            new ServiceProvider($overriddenServices, []),
+        ]));
+
+        $rootDir = ROOT_DIR;
+        $bootstrap = require ("$rootDir/bootstrap.php");
+        $appContainer = $bootstrap($rootDir, $overridingContainer);
+
+        return $appContainer;
+    }
+}
diff --git a/tests/PHPUnit/TestCase.php b/tests/PHPUnit/TestCase.php
index e51ff6828..d399e44c7 100644
--- a/tests/PHPUnit/TestCase.php
+++ b/tests/PHPUnit/TestCase.php
@@ -15,6 +15,15 @@ class TestCase extends \PHPUnit\Framework\TestCase
         parent::setUp();
 
         when('__')->returnArg();
+        when('_x')->returnArg();
+		when('esc_url')->returnArg();
+		when('esc_attr')->returnArg();
+		when('esc_attr__')->returnArg();
+		when('esc_html')->returnArg();
+		when('esc_html__')->returnArg();
+		when('esc_textarea')->returnArg();
+		when('sanitize_text_field')->returnArg();
+		when('wp_unslash')->returnArg();
 
         setUp();
     }
diff --git a/tests/PHPUnit/bootstrap.php b/tests/PHPUnit/bootstrap.php
index ba6ffb319..2e2b3350e 100644
--- a/tests/PHPUnit/bootstrap.php
+++ b/tests/PHPUnit/bootstrap.php
@@ -1,6 +1,10 @@
 <?php
 declare(strict_types=1);
-require_once __DIR__ . '/../../vendor/autoload.php';
-require_once __DIR__ . '/../stubs/WC_Payment_Gateway.php';
-require_once __DIR__ . '/../stubs/WC_Payment_Gateway_CC.php';
-require_once __DIR__ . '/../stubs/WC_Ajax.php';
+
+define('TESTS_ROOT_DIR', dirname(__DIR__));
+define('ROOT_DIR', dirname(TESTS_ROOT_DIR));
+
+require_once ROOT_DIR . '/vendor/autoload.php';
+require_once TESTS_ROOT_DIR . '/stubs/WC_Payment_Gateway.php';
+require_once TESTS_ROOT_DIR . '/stubs/WC_Payment_Gateway_CC.php';
+require_once TESTS_ROOT_DIR . '/stubs/WC_Ajax.php';