1_one_assert.rb

# Assume that create_invoice(customer, order) should:
# - create a row in the invoices table
# - that row should be charged_at nil
# - the amount should be the order's amount
describe "#create_invoice" do
  let(:customer) { create(:customer) }
  let(:order)    { create(:order, customer: customer, price: 123_56) }
  
  before do
    subject.create_invoice(customer, order)
  end
  
  it "should create a row in the invoices table" do
    expect(customer.invoices.size).to eq(1)
  end
  
  it "should set the invoice as not having been charged yet" do
    expect(customer.invoices.first.charged_at).to be_nil
  end
  
  it "should use the order's price for the invoice's amount" do
    expect(customer.invoices.first.amount_cents).to eq(123_56)
  end
end

2_agg_failures.rb

# Assume that create_invoice(customer, order) should:
# - create a row in the invoices table
# - that row should be charged_at nil
# - the amount should be the order's amount
describe "#create_invoice" do

  subject(:invoice_creator) { described_class.new }
  
  it "creates an uncharged invoice using the order's price as the amount" do
    customer = create(:customer)
    order    = create(:order, customer: customer, price: 123_56)
  
    invoice_creator.create_invoice(customer, order)

    aggregate_failures do
      expect(customer.invoices.size).to               eq(1)
      expect(customer.invoices.first.charged_at).to   eq(nil)
      expect(customer.invoices.first.amount_cents).to eq(123_56)
    end
  end
end

3_agg_better.rb

# Assume that create_invoice(customer, order) should:
# - create a row in the invoices table
# - that row should be charged_at nil
# - the amount should be the order's amount
describe "#create_invoice" do

  subject(:invoice_creator) { described_class.new }
  
  it "creates an uncharged invoice using the order's price as the amount" do
    customer = create(:customer)
    order    = create(:order, customer: customer, price: 123_56)
  
    invoice_creator.create_invoice(customer, order)

    expect(customer.invoices.size).to eq(1)
    invoice = customer.invoices.first
    
    aggregate_failures do
      expect(invoice.charged_at).to   eq(nil)
      expect(invoice.amount_cents).to eq(123_56)
    end
  end
end

4_add_complex.rb

# Assume that create_invoice(customer, order) should:
# - create a row in the invoices table
# - that row should be charged_at nil
# - the amount should be the order's amount
# - create a return_label on the invoice
# - set the return_label from address to the customer's
# - set the return_label to address to the company's
describe "#create_invoice" do

  subject(:invoice_creator) { described_class.new }
  
  it "creates an uncharged invoice using the order's price as the amount with a return label" do
    customer = create(:customer)
    order    = create(:order, customer: customer, price: 123_56)
  
    invoice_creator.create_invoice(customer, order)

    expect(customer.invoices.size).to eq(1)
    invoice = customer.invoices.first
    
    aggregate_failures do
      expect(invoice.charged_at).to   eq(nil)
      expect(invoice.amount_cents).to eq(123_56)
    end
    
    expect(invoice.return_label).not_to eq(nil)
    return_label = invoice.return_label
    
    aggregate_failures do
      expect(return_label.to_address).to   eq(Company.address)
      expect(return_label.from_address).to eq(customer.address)
    end
  end
end