---
title: 'Hidden gems: fake_braintree'
teaser:
tags: web,open source,fake_braintree
author: Mike Burns
published_on: 2012-09-13
---

The [fake_braintree](http://rubygems.org/gems/fake_braintree) gem makes your life easier when testing code that charges credit cards. It is a fake [Braintree](https://www.braintreepayments.com/) server that can be manipulated as you see fit.

Start by installing fake_braintree. In your `Gemfile`:

    gem 'braintree'

    group :test do
      gem 'fake_braintree'
    end

And in your `spec/spec_helper.rb`:

    require 'fake_braintree'

    RSpec.configure do |config|
      config.before do
        FakeBraintree.clear!
      end
    end

That RSpec configuration clears the fake data between test runs.

Now we can write a quick spec for `Purchase#transact`:

    require 'spec_helper'

    describe Purchase do
      it 'charges successfully' do
        transact.should be_true
      end

      it 'fails when the card is declined' do
        FakeBraintree.decline_all_cards!
        expect { transact }.to raise_error
      end

      def transact
        Purchase.new.transact
      end
    end

You can see fake_braintree peeking through there in the second spec, where we decline all credit card transactions. Since we clear fake data between test runs, this does not affect other tests.

We can make this pass [as normal](https://www.braintreepayments.com/docs/ruby/transactions/create):

    class Purchase
      def transact
        result = Braintree::Transaction.sale(
          amount: '1000.00',
          credit_card:  {
            number: '5105105105105100',
            expiration_date: '05/12'
          }
        )

        result.success? or raise result.errors.inspect
      end
    end

## That was easy

The fake_braintree gem is basically invisible until you need it. The Braintree implementation code is unchanged, and the success paths are the default.

You can set fake_braintree to [verify](https://github.com/thoughtbot/fake_braintree#verifying-credit-cards) or outright [decline](https://github.com/thoughtbot/fake_braintree#declining-credit-cards) credit cards (as above), and you can also [generate transactions](https://github.com/thoughtbot/fake_braintree#generating-transactions) as if the user really did buy something.

So stop being so hands-on with your credit card mocking and stubbing and give fake_braintree a try today!