diff --git a/tests/unit/Product/ProductCest.php b/tests/unit/Product/ProductCest.php
new file mode 100644
index 000000000..951e2da37
--- /dev/null
+++ b/tests/unit/Product/ProductCest.php
@@ -0,0 +1,67 @@
+<?php
+
+namespace Tests\Unit\Product;
+
+use UnitTester;
+use Webkul\Product\Repositories\ProductInventoryRepository;
+
+class ProductCest
+{
+    /**
+     * Test product inventory updation.
+     *
+     * @param  UnitTester  $I
+     * @return void
+     */
+    public function testProductInventoryUpdation(UnitTester $I): void
+    {
+        $product = $I->haveProduct(\Webkul\Core\Helpers\Laravel5Helper::SIMPLE_PRODUCT, [], ['simple']);
+
+        $updatedInventoriesQty = $this->getRandomUpdatedInventoriesQty($I, $product);
+
+        app(ProductInventoryRepository::class)->saveInventories([
+            'inventories' => $updatedInventoriesQty
+        ], $product);
+
+        $product->refresh();
+
+        $I->assertEquals(array_sum($updatedInventoriesQty), $product->inventories->sum('qty'));
+    }
+
+    /**
+     * Test old quantities.
+     *
+     * @param  UnitTester  $I
+     * @return void
+     */
+    public function testProductInventoriesQty(UnitTester $I): void
+    {
+        $product = $I->haveProduct(\Webkul\Core\Helpers\Laravel5Helper::SIMPLE_PRODUCT, [], ['simple']);
+
+        $oldInventoriesQty = $product->inventories->pluck('qty', 'inventory_source_id')->toArray();
+
+        $oldTotalQuantity = $product->inventories->sum('qty');
+
+        $I->assertEquals($oldTotalQuantity, array_sum($oldInventoriesQty));
+    }
+
+    /**
+     * Get random inventories qty for product.
+     *
+     * @param  UnitTester  $I
+     * @param  \Webkul\Product\Models\Product  $product
+     * @return array
+     */
+    private function getRandomUpdatedInventoriesQty(UnitTester $I, $product): array
+    {
+        $oldInventoriesQty = $product->inventories->pluck('qty', 'inventory_source_id');
+
+        $updatedInventoriesQty = [];
+
+        foreach ($oldInventoriesQty as $id => $oldInventoryQty) {
+            $updatedInventoriesQty[$id] = $I->fake()->numberBetween(500, 2000);
+        }
+
+        return $updatedInventoriesQty;
+    }
+}