Shopify/active_merchant — pull request #348 by AlexanderZaytsev (2012-04-25 12:11:03+00:00)
Title: Add mode mapping to two checkout integration helper

Added
```
mapping :mode, 'mode'
```

It is a required param for the Pass Through Product Parameter Set, see:
https://www.2checkout.com/blog/knowledge-base/merchants/tech-support/3rd-party-carts/parameter-sets/pass-through-product-parameter-set/