Maybe you can do something like this
````
let(:product) { VCR.use_cassette('bp/product_with_variants') { describe_class.create(params) } }
`````
or this:
````
let(:product) { described_class.create(params) }

it 'creates new product' do
  VCR.use_cassette('bp/product_with_variants') do
    expect(product)...
  end
end
````
To avoid using instance variables.