test: financial transaction model (foodcoops#1008 , PR foodcoops#1031)

spec/factories/financial_transaction.rb

@@ -11,5 +11,9 @@
     # transactions we'd use the default. This, however, is the easiest way to
     # get the factory going. If you want equal types, specify it explicitly.
     financial_transaction_type
+
+    trait :pending do
+      amount { nil }
+    end
   end
 end

spec/models/financial_transaction_spec.rb

@@ -0,0 +1,30 @@
+require_relative '../spec_helper'
+
+describe FinancialTransaction do
+  let!(:ordergroup) { create(:ordergroup) }
+  let!(:ft) { create(:financial_transaction, ordergroup: ordergroup, amount: 20) }
+
+  it 'updates the amount of the ordergroup balance' do
+    expect(ordergroup.account_balance).to eq(20)
+    create(:financial_transaction, ordergroup: ordergroup, amount: 10)
+    expect(ordergroup.account_balance).to eq(30)
+  end
+
+  it 'can be reverted' do
+    ft.revert!(ft.user)
+    expect(ft).to be_hidden
+    expect(ordergroup.financial_transactions.count).to eq 2
+    expect(ordergroup.financial_transactions.last.amount).to eq(-20)
+    expect(ordergroup.financial_transactions.last.reverts).to eq ft
+    expect(ordergroup.account_balance).to eq 0
+  end
+
+  context 'with a pending transaction' do
+    let!(:ft) { create(:financial_transaction, :pending, ordergroup: ordergroup) }
+
+    it 'fails on revert' do
+      puts ft.inspect
+      expect { ft.revert!(ft.user) }.to raise_error(RuntimeError, 'Pending Transaction cannot be reverted')
+    end
+  end
+end