Stripe Stripe-Mock refunding

refund_stripe.rb

gem 'stripe', '1.31.0'
require 'stripe'
Stripe.api_key = <insert API key here>

token = Stripe::Token.create(
  :card => {
    :number => "4242424242424242",
    :exp_month => 3,
    :exp_year => 2017,
    :cvc => "314"
  }
)

charge_info = {
  source: token['id'],
  amount: 1000,
  currency: 'usd'
}

charge = Stripe::Charge.create(charge_info)

refund1 = charge.refund(amount: 100) # => no error
puts refund1.amount_refunded # => 100

refund2 = charge.refund(amount: 1000) # => `handle_api_error': Refund amount ($1.00) is greater than unrefunded amount on charge ($0.90) (Stripe::InvalidRequestError)
puts refund2.amount_refunded # ?? (exception occurred)

refund_stripe_mock.rb

gem 'stripe-ruby-mock', '2.2.2'
require 'stripe_mock'

Stripe.api_key = 'test_key'
StripeMock.start

stripe_helper = StripeMock.create_test_helper

token = stripe_helper.generate_card_token

charge_info = {
  source: token,
  amount: 1000,
  currency: 'usd'
}

charge = Stripe::Charge.create(charge_info)

refund1 = charge.refund(amount: 100) # => no error
puts refund1.amount_refunded # => 100

refund2 = charge.refund(amount: 1000) # => no error
puts refund2.amount_refunded # => 1100