Effective Testing with RSpec 3

Testing the Invalid Case

So far, our integration spec checks only the “happy path” of saving a valid expense. Let’s add a second spec that tries an expense missing a payee:

06-integration-specs/07/expense_tracker/spec/integration/app/ledger_spec.rb

context 'when the expense lacks a payee' do
  it 'rejects the expense as invalid' do
    expense.delete('payee')

    result = ledger.record(expense)

    expect(result).not_to be_success
    expect(result.expense_id).to eq(nil)
    expect(result.error_message).to include('`payee` is required')

    expect(DB[:expenses].count).to eq(0)
  end
end

Here, the Ledger instance should return the correct failure status and message, and the database should have no expenses in it.