```ruby
require 'test_helper'

class ProductTest < ActiveSupport::TestCase
  # test "the truth" do
  #   assert true
  # end
end
```

Add model test for Product properties
user
```ruby
require 'test_helper'

class ProductTest < ActiveSupport::TestCase
  test "product attributes must not be empty" do
    # Properties must not be empty. 
    product = Product.new
    assert product.invalid?
    assert product.errors[:title].any?
    assert product.errors[:description].any?
    assert product.errors[:price].any?
    assert product.errors[:image_url].any?
  end
end
```
assistant