Merge pull request stripe-ruby-mock#572 from MaicolBen/bug/fee-calculation

Fix net/fee calculation in balance transaction

Author: alexmamonchik

lib/stripe_mock/instance.rb

@@ -175,7 +175,8 @@ def new_balance_transaction(prefix, params = {})
       amount = params[:amount]
       unless amount.nil?
         # Fee calculation
-        params[:fee] ||= (30 + (amount.abs * 0.029).ceil) * (amount > 0 ? 1 : -1)
+        calculate_fees(params) unless params[:fee]
+        params[:net] = amount - params[:fee]
         params[:amount] = amount * @conversion_rate
       end
       @balance_transactions[id] = Data.mock_balance_transaction(params.merge(id: id))
@@ -196,5 +197,31 @@ def to_faraday_hash(hash)
       response = Struct.new(:data)
       response.new(hash)
     end
+
+    def calculate_fees(params)
+      application_fee = params[:application_fee] || 0
+      params[:fee] = processing_fee(params[:amount]) + application_fee
+      params[:fee_details] = [
+        {
+          amount: processing_fee(params[:amount]),
+          application: nil,
+          currency: params[:currency] || StripeMock.default_currency,
+          description: "Stripe processing fees",
+          type: "stripe_fee"
+        }
+      ]
+      if application_fee
+        params[:fee_details] << {
+          amount: application_fee,
+          currency: params[:currency] || StripeMock.default_currency,
+          description: "Application fee",
+          type: "application_fee"
+        }
+      end
+    end
+
+    def processing_fee(amount)
+      (30 + (amount.abs * 0.029).ceil) * (amount > 0 ? 1 : -1)
+    end
   end
 end

lib/stripe_mock/request_handlers/charges.rb

@@ -41,7 +41,7 @@ def new_charge(route, method_url, params, headers)
         end
 
         ensure_required_params(params)
-        bal_trans_params = { amount: params[:amount], source: id }
+        bal_trans_params = { amount: params[:amount], source: id, application_fee: params[:application_fee] }
 
         balance_transaction_id = new_balance_transaction('txn', bal_trans_params)
 

spec/shared_stripe_examples/charge_examples.rb

@@ -163,15 +163,19 @@
   end
 
   it "creates a balance transaction" do
+    amount = 300
+    fee = 10
     charge = Stripe::Charge.create({
-      amount: 300,
+      amount: amount,
       currency: 'USD',
-      source: stripe_helper.generate_card_token
+      source: stripe_helper.generate_card_token,
+      application_fee: fee,
     })
     bal_trans = Stripe::BalanceTransaction.retrieve(charge.balance_transaction)
-    expect(bal_trans.amount).to eq(charge.amount)
-    expect(bal_trans.fee).to eq(39)
+    expect(bal_trans.amount).to eq(amount)
+    expect(bal_trans.fee).to eq(39 + fee)
     expect(bal_trans.source).to eq(charge.id)
+    expect(bal_trans.net).to eq(amount - bal_trans.fee)
   end
 
   context 'when conversion rate is set' do