diff --git a/modules/ubercart/src/Plugin/migrate/source/d6/Order.php b/modules/ubercart/src/Plugin/migrate/source/d6/Order.php
index 223e8d9..c3ad717 100644
--- a/modules/ubercart/src/Plugin/migrate/source/d6/Order.php
+++ b/modules/ubercart/src/Plugin/migrate/source/d6/Order.php
@@ -19,16 +19,24 @@ class Order extends DrupalSqlBase {
    * {@inheritdoc}
    */
   public function query() {
-    $query = $this->select('uc_orders', 'uo')
-      ->fields('uo');
-    return $query;
+    return $this->select('uc_orders', 'uo')
+      ->fields('uo', [
+        'order_id',
+        'uid',
+        'order_status',
+        'primary_email',
+        'host',
+        'data',
+        'created',
+        'modified',
+      ]);
   }
 
   /**
    * {@inheritdoc}
    */
   public function fields() {
-    $fields = [
+    return [
       'order_id' => $this->t('Order ID'),
       'uid' => $this->t('User ID of order'),
       'order_status' => $this->t('Order status'),
@@ -37,9 +45,8 @@ class Order extends DrupalSqlBase {
       'data' => $this->t('Order attributes'),
       'created' => $this->t('Date/time of order creation'),
       'modified' => $this->t('Date/time of last order modification'),
+      'order_item_id' => $this->t('Order item IDs'),
     ];
-
-    return $fields;
   }
 
   /**
@@ -55,6 +62,7 @@ class Order extends DrupalSqlBase {
     unset($data['cc_data']);
     $row->setSourceProperty('data', $data);
 
+    // Puts product order ids for this order in the row.
     $order_id = $row->getSourceProperty('order_id');
     $query = $this->select('uc_order_products', 'uop')
       ->fields('uop', ['order_product_id'])
diff --git a/modules/ubercart/tests/src/Kernel/Plugin/migrate/source/d6/OrderTest.php b/modules/ubercart/tests/src/Kernel/Plugin/migrate/source/d6/OrderTest.php
new file mode 100644
index 0000000..3dc5db7
--- /dev/null
+++ b/modules/ubercart/tests/src/Kernel/Plugin/migrate/source/d6/OrderTest.php
@@ -0,0 +1,185 @@
+<?php
+
+namespace Drupal\Tests\commerce_migrate_ubercart\Kernel\Plugin\migrate\source\d6;
+
+use Drupal\Tests\migrate\Kernel\MigrateSqlSourceTestBase;
+
+/**
+ * Tests Uberart order plugin.
+ *
+ * @covers \Drupal\commerce_migrate_ubercart\Plugin\migrate\source\d6\Order
+ *
+ * @group commerce_migrate
+ * @group commerce_migrate_ubercart_d6
+ */
+class OrderTest extends MigrateSqlSourceTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = [
+    'migrate_drupal',
+    'commerce_migrate_ubercart',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  public function providerSource() {
+    $tests = [];
+    $tests[0]['source_data']['uc_orders'] =
+      [
+        [
+          'order_id' => '1',
+          'uid' => '2',
+          'order_status' => 'payment_received',
+          'order_total' => '22.99000',
+          'product_count' => '2',
+          'primary_email' => 'f.bar@example.com',
+          'delivery_first_name' => '',
+          'delivery_last_name' => '',
+          'delivery_phone' => '',
+          'delivery_company' => '',
+          'delivery_street1' => '',
+          'delivery_street2' => '',
+          'delivery_city' => '',
+          'delivery_zone' => '',
+          'delivery_postal_code' => '',
+          'delivery_country' => '',
+          'billing_first_name' => 'Foo',
+          'billing_last_name' => 'Bar',
+          'billing_phone' => '123-4567',
+          'billing_company' => 'Acme',
+          'billing_street1' => '1 Coyote Way',
+          'billing_street2' => 'Utah',
+          'billing_city' => 'Salt Lake',
+          'billing_zone' => '58',
+          'billing_postal_code' => '11111',
+          'billing_country' => '840',
+          'payment_method' => 'cod',
+          'data' => 'a:0:{}',
+          'created' => '1492868907',
+          'modified' => '1498620003',
+          'host' => '192.168.0.2',
+          'currency' => 'USD',
+        ],
+        [
+          'order_id' => '2',
+          'uid' => '2',
+          'order_status' => 'payment_received',
+          'order_total' => '22.99000',
+          'product_count' => '2',
+          'primary_email' => 'f.bar@example.com',
+          'delivery_first_name' => '',
+          'delivery_last_name' => '',
+          'delivery_phone' => '',
+          'delivery_company' => '',
+          'delivery_street1' => '',
+          'delivery_street2' => '',
+          'delivery_city' => '',
+          'delivery_zone' => '',
+          'delivery_postal_code' => '',
+          'delivery_country' => '',
+          'billing_first_name' => 'Foo',
+          'billing_last_name' => 'Bar',
+          'billing_phone' => '555-4567',
+          'billing_company' => 'Acme',
+          'billing_street1' => '1 Coyote Way',
+          'billing_street2' => 'Utah',
+          'billing_city' => 'Salt Lake',
+          'billing_zone' => '58',
+          'billing_postal_code' => '11111',
+          'billing_country' => '840',
+          'payment_method' => 'cod',
+          'data' => 'a:0:{}',
+          'created' => '1492868907',
+          'modified' => '1498630003',
+          'host' => '192.168.0.2',
+          'currency' => 'USD',
+        ],
+      ];
+    $tests[0]['source_data']['uc_order_products'] =
+      [
+        [
+          'order_product_id' => '1',
+          'order_id' => '1',
+          'nid' => '1',
+          'title' => 'Product 1',
+          'manufacturer' => 'Someone',
+          'model' => 'Product 1 - 001',
+          'qty' => '2',
+          'cost' => '500.00000',
+          'price' => '600.00000',
+          'weight' => '2',
+          'data' => 'a:2:{s:9:"shippable";s:1:"1";s:6:"module";s:10:"uc_product";}',
+        ],
+        [
+          'order_product_id' => '3',
+          'order_id' => '1',
+          'nid' => '4',
+          'title' => 'Towel',
+          'manufacturer' => 'Acme',
+          'model' => 'Towel - 001',
+          'qty' => '2',
+          'cost' => '500.00000',
+          'price' => '600.00000',
+          'weight' => '2',
+          'data' => 'a:2:{s:9:"shippable";s:1:"1";s:6:"module";s:10:"uc_product";}',
+        ],
+        [
+          'order_product_id' => '4',
+          'order_id' => '1',
+          'nid' => '3',
+          'title' => 'Babel fish',
+          'manufacturer' => 'Someone',
+          'model' => 'Bable fish - 001',
+          'qty' => '2',
+          'cost' => '500.00000',
+          'price' => '600.00000',
+          'weight' => '2',
+          'data' => 'a:2:{s:9:"shippable";s:1:"1";s:6:"module";s:10:"uc_product";}',
+        ],
+        [
+          'order_product_id' => '9',
+          'order_id' => '2',
+          'nid' => '5',
+          'title' => 'Cake',
+          'manufacturer' => 'Someone',
+          'model' => 'Cake - 001',
+          'qty' => '2',
+          'cost' => '500.00000',
+          'price' => '600.00000',
+          'weight' => '2',
+          'data' => 'a:2:{s:9:"shippable";s:1:"1";s:6:"module";s:10:"uc_product";}',
+        ],
+      ];
+    // The expected results.
+    $tests[0]['expected_data'] =
+      [
+        [
+          'order_id' => '1',
+          'uid' => '2',
+          'order_status' => 'payment_received',
+          'primary_email' => 'f.bar@example.com',
+          'data' => [],
+          'created' => '1492868907',
+          'modified' => '1498620003',
+          'host' => '192.168.0.2',
+          'order_item_ids' => [1, 3, 4],
+        ],
+        [
+          'order_id' => '2',
+          'uid' => '2',
+          'order_status' => 'payment_received',
+          'primary_email' => 'f.bar@example.com',
+          'data' => [],
+          'created' => '1492868907',
+          'modified' => '1498630003',
+          'host' => '192.168.0.2',
+          'order_item_ids' => [9],
+        ],
+      ];
+    return $tests;
+  }
+
+}