thoughtbot--factory_bot/spec/acceptance/build_spec.rb

describe "a built instance" do
  include FactoryBot::Syntax::Methods

  before do
    define_model("User")

    define_model("Post", user_id: :integer) do
      belongs_to :user
    end

    FactoryBot.define do
      factory :user

      factory :post do
        user
      end
    end
  end

  subject { build(:post) }

  it { should be_new_record }

  context "when the :use_parent_strategy config option is set to false" do
    before { FactoryBot.use_parent_strategy = false }

    it "assigns and saves associations" do
      expect(subject.user).to be_kind_of(User)
      expect(subject.user).not_to be_new_record
    end
  end

  context "when the :use_parent_strategy config option is set to true" do
    before { FactoryBot.use_parent_strategy = true }

    it "assigns but does not save associations" do
      expect(subject.user).to be_kind_of(User)
      expect(subject.user).to be_new_record
    end
  end
end

describe "a built instance with strategy: :create" do
  include FactoryBot::Syntax::Methods

  before do
    define_model("User")

    define_model("Post", user_id: :integer) do
      belongs_to :user
    end

    FactoryBot.define do
      factory :user

      factory :post do
        association(:user, strategy: :create)
      end
    end
  end

  subject { build(:post) }

  it { should be_new_record }

  it "assigns and saves associations" do
    expect(subject.user).to be_kind_of(User)
    expect(subject.user).not_to be_new_record
  end
end

describe "calling `build` with a block" do
  include FactoryBot::Syntax::Methods

  before do
    define_model("Company", name: :string)

    FactoryBot.define do
      factory :company
    end
  end

  it "passes the built instance" do
    build(:company, name: "thoughtbot") do |company|
      expect(company.name).to eq("thoughtbot")
    end
  end

  it "returns the built instance" do
    expected = nil
    result = build(:company) do |company|
      expected = company
      "hello!"
    end
    expect(result).to eq expected
  end
end