/**
 * Constructor
 */
public function __construct() {

    if ( ! Iconic_WDS_Core_Helpers::is_plugin_active( 'woocommerce/woocommerce.php' ) && ! Iconic_WDS_Core_Helpers::is_plugin_active( 'woocommerce-old/woocommerce.php' ) ) {
        return;
        // It stops right here!!!
    }

}

install_dependencies() {
    WP_SITE_URL="http://localhost:8080"
    WP_PLUGIN_DIR=$(pwd)
    WP_DB_DATA="$WP_PLUGIN_DIR/tests/data/db.sql"

    cd "$WP_CORE_DIR"
    curl -O https://raw.githubusercontent.com/wp-cli/builds/gh-pages/phar/wp-cli.phar
    php wp-cli.phar core config --dbname=$DB_NAME --dbuser=$DB_USER --dbpass=$DB_PASS --dbhost=$DB_HOST --dbprefix=wptests_
    php wp-cli.phar db import $WP_DB_DATA
    php wp-cli.phar search-replace "http://local.wordpress.test" "$WP_SITE_URL"
    php wp-cli.phar theme install twentyseventeen --activate
    php wp-cli.phar plugin install https://downloads.wordpress.org/plugin/woocommerce.${WC_VERSION}.zip --activate
    php wp-cli.phar plugin install https://downloads.wordpress.org/plugin/posts-to-posts.${P2P_VERSION}.zip --activate
    php wp-cli.phar plugin install $WP_PLUGIN_DIR/plugins/iconic-private-plugin.zip --activate
    php wp-cli.phar plugin list
}

/**
 * Setup the unit testing environment.
 */
public function __construct() {
    // phpcs:disable WordPress.PHP.DiscouragedPHPFunctions, WordPress.PHP.DevelopmentFunctions
    ini_set( 'display_errors', 'on' );
    error_reporting( E_ALL );
    // phpcs:enable WordPress.PHP.DiscouragedPHPFunctions, WordPress.PHP.DevelopmentFunctions

    // Ensure server variable is set for WP email functions.
    // phpcs:disable WordPress.VIP.SuperGlobalInputUsage.AccessDetected
    if ( ! isset( $_SERVER['SERVER_NAME'] ) ) {
        $_SERVER['SERVER_NAME'] = 'localhost';
    }
    // phpcs:enable WordPress.VIP.SuperGlobalInputUsage.AccessDetected

    $this->tests_dir    = dirname( __FILE__ );
    $this->plugin_dir   = dirname( $this->tests_dir );
    $this->wp_tests_dir = getenv( 'WP_TESTS_DIR' ) ? getenv( 'WP_TESTS_DIR' ) : rtrim( sys_get_temp_dir(), '/\' ) . '/wordpress-tests-lib';

    // load test function so tests_add_filter() is available.
    require_once $this->wp_tests_dir . '/includes/functions.php';

    // load Dependencies.
    tests_add_filter( 'muplugins_loaded', array( $this, 'my_custom_plugin_manually_load_plugin' ) );

    // load the WP testing environment.
    require_once $this->wp_tests_dir . '/includes/bootstrap.php';
}

/**
 * Load Dependencies
 */
public function my_custom_plugin_manually_load_plugin() {
    $this->plugins_dir = ABSPATH . str_replace( site_url() . '/', '', plugins_url() ) . '/';

    // Load dependencies.
    require_once $this->plugins_dir . 'woocommerce/woocommerce.php';
    require_once $this->plugins_dir . 'iconic/iconic-private-plugin.php';

    // Load plugin.
    require_once $this->plugin_dir . '/my-custom-plugin.php';

    global $my_custom_plugin;
    $my_custom_plugin = new My_Custom_Plugin_Class();
}

<?php
/**
 * Sql test case.
 */
class SqlTest extends WP_UnitTestCase {

    /**
     * Set up fixtures before class for all tests in SqlTest Class.
     *
     * @param object $factory passed by WP_UnitTestCase.
     */
    public static function wpSetUpBeforeClass( $factory ) {
        self::createFixtures();
        self::createSettings();
    }

    public function setUp() {
        self::set_active_plugins();
    }

    public static function set_active_plugins() {
        $plugins = array (
            'iconic-woo-delivery-slots-premium/iconic-woo-delivery-slots.php',
            'posts-to-posts/posts-to-posts.php',
            'woocommerce/woocommerce.php'
        );

        update_option('active_plugins', $plugins);
    }

    /**
     * Warehouses fixtures
     */
    public static function createFixtures() {
        // [...]
    }

    /**
     * Create timeslots
     */
    public static function createSettings() {
        $settings = array (
            // [...]
        );

        update_option( 'iconic_private_plugin_settings', $settings );
        global $iconic_private_plugin;
        $iconic_private_plugin->settings = $settings;
    }

    /**
     * Test for custom_function.
     */
    public function test_custom_function() {
        global $my_custom_plugin, $iconic_private_plugin;

        print_r($iconic_private_plugin);
        // Class properties are empty, since construct method stop at WooCommerce activation check.

        $this->assertTrue(true);
    }

}