fix: correct return of subscription items

[augustoccesar]

Original PR: #811 . Accidentally closed

Description

Currently, the whole hash is passed to mock_list_object instead of only the values. This generates an incorrect response.

Example

With:

Stripe::SubscriptionItem.create(plan: plan.id, subscription: subscription.id, quantity: 2)
Stripe::SubscriptionItem.create(plan: plan2.id, subscription: subscription.id, quantity: 20)

Then:

Stripe::SubscriptionItem.list(subscription: subscription.id)

Returns:

=> #<Stripe::ListObject:0x1e00> JSON: {
  "object": "list",
  "data": [
    [
      "test_si_7",
      {"id":"test_si_7","object":"subscription_item","created":1504716183,"metadata":{},"plan":{"id":"silver_plan","object":"plan","active":true,"aggregate_usage":null,"amount":1337,"billing_scheme":"per_unit","created":1466698898,"currency":"usd","interval":"month","interval_count":1,"livemode":false,"metadata":{},"nickname":"My Mock Plan","product":"stripe_mock_default_product_id","tiers":null,"tiers_mode":null,"transform_usage":null,"trial_period_days":null,"usage_type":"licensed"},"quantity":2,"subscription":"test_su_4"}
    ],
    [
      "test_si_8",
      {"id":"test_si_8","object":"subscription_item","created":1504716183,"metadata":{},"plan":{"id":"one_more_1_plan","object":"plan","active":true,"aggregate_usage":null,"amount":100,"billing_scheme":"per_unit","created":1466698898,"currency":"usd","interval":"month","interval_count":1,"livemode":false,"metadata":{},"nickname":"My Mock Plan","product":"stripe_mock_default_product_id","tiers":null,"tiers_mode":null,"transform_usage":null,"trial_period_days":null,"usage_type":"licensed"},"quantity":20,"subscription":"test_su_4"}
    ]
  ],
  "url": "/v1/arrays",
  "has_more": false
}

But should return:

=> #<Stripe::ListObject:0x1e00> JSON: {
  "object": "list",
  "data": [
    {"id":"test_si_8","object":"subscription_item","created":1504716183,"metadata":{},"plan":{"id":"one_more_1_plan","object":"plan","active":true,"aggregate_usage":null,"amount":100,"billing_scheme":"per_unit","created":1466698898,"currency":"usd","interval":"month","interval_count":1,"livemode":false,"metadata":{},"nickname":"My Mock Plan","product":"stripe_mock_default_product_id","tiers":null,"tiers_mode":null,"transform_usage":null,"trial_period_days":null,"usage_type":"licensed"},"quantity":20,"subscription":"test_su_4"},
    {"id":"test_si_7","object":"subscription_item","created":1504716183,"metadata":{},"plan":{"id":"silver_plan","object":"plan","active":true,"aggregate_usage":null,"amount":1337,"billing_scheme":"per_unit","created":1466698898,"currency":"usd","interval":"month","interval_count":1,"livemode":false,"metadata":{},"nickname":"My Mock Plan","product":"stripe_mock_default_product_id","tiers":null,"tiers_mode":null,"transform_usage":null,"trial_period_days":null,"usage_type":"licensed"},"quantity":2,"subscription":"test_su_4"}
  ],
  "url": "/v1/hashs",
  "has_more": false
}

Documentation reference

https://stripe.com/docs/api/subscription_items/list?lang=ruby