Effective Testing with RSpec 3

Handling Failure

Now that your specs are testing the “happy path” of a successful expense, let’s turn our attention to the failure case. You can apply the hard-won knowledge from the previous sections, and start with an already-factored before hook. Here, the setup code will fill the RecordResult value object with a false success status and an error message:

05-unit-specs/06/expense_tracker/spec/unit/app/api_spec.rb

context 'when the expense fails validation' do
  let(:expense) { { 'some' => 'data' } }

  before do
    allow(ledger).to receive(:record)
      .with(expense)
      .and_return(RecordResult.new(false, 417, 'Expense incomplete'))
  end

  it 'returns an error message' do
    post '/expenses', JSON.generate(expense) ...