amount to the other account" do source = Account.new(50, :USD) target = mock('target account') target.should_receive(:deposit).with(Money.new (5, :USD)) source.transfer(5, :USD).to(target) end it "reduces its balance by the transfer amount" do source = Account.new(50, :USD) target = stub('target account') source.transfer(5, :USD).to(target) source.balance.should == Money.new(45, :USD) end end end