diff --git a/.rspec b/.rspec
new file mode 100644
index 0000000..c99d2e7
--- /dev/null
+++ b/.rspec
@@ -0,0 +1 @@
+--require spec_helper
diff --git a/Gemfile.lock b/Gemfile.lock
index 3368298..3dc5e28 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -2,24 +2,13 @@ PATH
   remote: .
   specs:
     norma43_parser (4.0.0)
-      virtus (~> 1.0)
       zeitwerk (~> 2.0)
 
 GEM
   remote: https://rubygems.org/
   specs:
     ast (2.4.2)
-    axiom-types (0.1.1)
-      descendants_tracker (~> 0.0.4)
-      ice_nine (~> 0.11.0)
-      thread_safe (~> 0.3, >= 0.3.1)
-    coercible (1.0.0)
-      descendants_tracker (~> 0.0.1)
-    descendants_tracker (0.0.4)
-      thread_safe (~> 0.3, >= 0.3.1)
     diff-lcs (1.5.1)
-    equalizer (0.0.11)
-    ice_nine (0.11.2)
     json (2.7.2)
     json (2.7.2-java)
     language_server-protocol (3.17.0.3)
@@ -66,14 +55,7 @@ GEM
     ruby-progressbar (1.13.0)
     strscan (3.1.0)
     strscan (3.1.0-java)
-    thread_safe (0.3.6)
-    thread_safe (0.3.6-java)
     unicode-display_width (2.5.0)
-    virtus (1.0.5)
-      axiom-types (~> 0.1)
-      coercible (~> 1.0)
-      descendants_tracker (~> 0.0, >= 0.0.3)
-      equalizer (~> 0.0, >= 0.0.9)
     zeitwerk (2.6.15)
 
 PLATFORMS
diff --git a/lib/norma43/models.rb b/lib/norma43/models.rb
index 9a361ad..d05f23e 100644
--- a/lib/norma43/models.rb
+++ b/lib/norma43/models.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require "virtus"
-
 module Norma43
   module Models
     DEBIT_CODE = 1
diff --git a/lib/norma43/models/account.rb b/lib/norma43/models/account.rb
index 91a2a69..4654f1d 100644
--- a/lib/norma43/models/account.rb
+++ b/lib/norma43/models/account.rb
@@ -1,30 +1,62 @@
 # frozen_string_literal: true
 
-require "virtus"
-
 module Norma43
   module Models
     class Account
-      include Virtus.model
+      include Mixins::AttributesAssignment
+
+      attr_accessor :bank_code,
+        :branch_code,
+        :account_number,
+        :start_date,
+        :end_date,
+        :balance_code,
+        :balance_amount,
+        :currency_code,
+        :information_mode_code,
+        :abbreviated_name,
+        :debit_entries,
+        :debit_amount,
+        :credit_entries,
+        :credit_amount,
+        :transactions
 
-      attribute :bank_code
-      attribute :branch_code
-      attribute :account_number
-      attribute :start_date
-      attribute :end_date
-      attribute :balance_code
-      attribute :balance_amount
-      attribute :currency_code
-      attribute :information_mode_code
-      attribute :abbreviated_name
-      attribute :debit_entries
-      attribute :debit_amount
-      attribute :credit_entries
-      attribute :credit_amount
-      attribute :transactions, Array[Transaction]
+      def initialize(attributes = EMPTY_ATTRIBUTES)
+        @bank_code,
+        @branch_code,
+        @account_number,
+        @start_date,
+        @end_date,
+        @balance_code,
+        @balance_amount,
+        @currency_code,
+        @information_mode_code,
+        @abbreviated_name,
+        @debit_entries,
+        @debit_amount,
+        @credit_entries,
+        @credit_amount,
+        transactions = Hash(attributes).values_at(
+          :bank_code,
+          :branch_code,
+          :account_number,
+          :start_date,
+          :end_date,
+          :balance_code,
+          :balance_amount,
+          :currency_code,
+          :information_mode_code,
+          :abbreviated_name,
+          :debit_entries,
+          :debit_amount,
+          :credit_entries,
+          :credit_amount,
+          :transactions)
+        @transactions = Array(transactions).map { |attrs| Transaction.new(attrs) }
+      end
 
       def iban
-        @iban ||= SpanishIban.from_account(self)
+        SpanishIban.from_account(self)
       end
     end
   end
diff --git a/lib/norma43/models/additional_currency.rb b/lib/norma43/models/additional_currency.rb
index e071374..c7e495b 100644
--- a/lib/norma43/models/additional_currency.rb
+++ b/lib/norma43/models/additional_currency.rb
@@ -1,16 +1,22 @@
 # frozen_string_literal: true
 
-require "virtus"
-
 module Norma43
   module Models
     class AdditionalCurrency
-      include Virtus.model
+      include Mixins::AttributesAssignment
+
+      attr_accessor :data_code, :currency_code, :amount, :free
 
-      attribute :data_code
-      attribute :currency_code
-      attribute :amount
-      attribute :free
+      def initialize(attributes = EMPTY_ATTRIBUTES)
+        @data_code,
+        @currency_code,
+        @amount,
+        @free = Hash(attributes).values_at(
+          :data_code,
+          :currency_code,
+          :amount,
+          :free)
+      end
     end
   end
 end
diff --git a/lib/norma43/models/additional_item.rb b/lib/norma43/models/additional_item.rb
index 1b6b0a3..abf0c94 100644
--- a/lib/norma43/models/additional_item.rb
+++ b/lib/norma43/models/additional_item.rb
@@ -1,15 +1,20 @@
 # frozen_string_literal: true
 
-require "virtus"
-
 module Norma43
   module Models
     class AdditionalItem
-      include Virtus.model
+      include Mixins::AttributesAssignment
+
+      attr_accessor :data_code, :item_1, :item_2
 
-      attribute :data_code
-      attribute :item_1
-      attribute :item_2
+      def initialize(attributes = EMPTY_ATTRIBUTES)
+        @data_code,
+        @item_1,
+        @item_2 = Hash(attributes).values_at(
+          :data_code,
+          :item_1,
+          :item_2)
+      end
     end
   end
 end
diff --git a/lib/norma43/models/document.rb b/lib/norma43/models/document.rb
index a6b5065..5068998 100644
--- a/lib/norma43/models/document.rb
+++ b/lib/norma43/models/document.rb
@@ -1,22 +1,41 @@
 # frozen_string_literal: true
 
-require "virtus"
-
 module Norma43
   module Models
     class Document
-      include Virtus.model
+      include Mixins::AttributesAssignment
+
+      attr_accessor :id, :created_at, :delivery_number, :file_type, :name, :number_of_lines, :accounts
 
-      attribute :id
-      attribute :created_at
-      attribute :delivery_number
-      attribute :file_type
-      attribute :name
-      attribute :number_of_lines
-      attribute :accounts, Array[Account]
+      def initialize(attributes = EMPTY_ATTRIBUTES)
+        @id,
+        @created_at,
+        @delivery_number,
+        @file_type,
+        @name,
+        @number_of_lines,
+        accounts = Hash(attributes).values_at(
+          :id,
+          :created_at,
+          :delivery_number,
+          :file_type,
+          :name,
+          :number_of_lines,
+          :accounts)
+        @accounts = Array(accounts).map { |account| Account.new(account) }
+      end
 
+      # @deprecated Please ask each transaction inside accounts for their transaction_date instead
       def transaction_date
-        accounts.map(&:date).compact.first
+        warn "[DEPRECATION] `transaction_date` is deprecated, use `#transaction_date` from transactions in `#accounts` instead"
+        date = nil
+
+        accounts.flat_map(&:transactions).each { |transaction|
+          date = transaction&.transaction_date
+          break unless date.nil?
+        }
+
+        date
       end
     end
   end
diff --git a/lib/norma43/models/mixins/attributes_assignment.rb b/lib/norma43/models/mixins/attributes_assignment.rb
new file mode 100644
index 0000000..25a748e
--- /dev/null
+++ b/lib/norma43/models/mixins/attributes_assignment.rb
@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+module Norma43
+  module Models
+    module Mixins
+      module AttributesAssignment
+        EMPTY_ATTRIBUTES = {}.freeze
+
+        def attributes=(new_attributes)
+          Hash(new_attributes).each do |attr_name, attr_value|
+            attr_writer_method_name = "#{attr_name}=".to_sym
+            next unless public_methods(false).include?(attr_writer_method_name)
+
+            public_send(attr_writer_method_name, attr_value)
+          end
+        end
+
+        def attributes
+          instance_variables.map { |ivar_name|
+            attr_reader_method_name = ivar_name.to_s.delete_prefix("@").to_sym
+            next unless public_methods(false).include?(attr_reader_method_name)
+
+            attr_value = public_send(attr_reader_method_name)
+
+            [attr_reader_method_name, attr_value]
+          }.compact.to_h
+        end
+        alias_method :to_hash, :attributes # Implicit coercion for `Hash(model)`
+        alias_method :to_h,    :attributes # Explicit coercion
+      end
+    end
+  end
+end
diff --git a/lib/norma43/models/transaction.rb b/lib/norma43/models/transaction.rb
index 1f52245..5853ecc 100644
--- a/lib/norma43/models/transaction.rb
+++ b/lib/norma43/models/transaction.rb
@@ -1,24 +1,50 @@
 # frozen_string_literal: true
 
-require "virtus"
-
 module Norma43
   module Models
     class Transaction
-      include Virtus.model
+      include Mixins::AttributesAssignment
+
+      attr_accessor :origin_branch_code,
+        :transaction_date,
+        :value_date,
+        :shared_item,
+        :own_item,
+        :amount_code,
+        :amount,
+        :document_number,
+        :reference_1,
+        :reference_2,
+        :additional_items,
+        :additional_currency
+
+      def initialize(attributes = EMPTY_ATTRIBUTES)
+        @origin_branch_code,
+        @transaction_date,
+        @value_date,
+        @shared_item,
+        @own_item,
+        @amount_code,
+        @amount,
+        @document_number,
+        @reference_1,
+        @reference_2,
+        additional_items,
+        additional_currency = Hash(attributes).values_at(
+          :origin_branch_code,
+          :transaction_date,
+          :value_date,
+          :shared_item,
+          :own_item,
+          :amount_code,
+          :amount,
+          :document_number,
+          :reference_1,
+          :reference_2)
+        @additional_items = Array(additional_items).map { |attrs| AdditionalItem.new(attrs) }
+        @additional_currency = AdditionalCurrency.new(additional_currency) if additional_currency
+      end
 
-      attribute :origin_branch_code
-      attribute :transaction_date
-      attribute :value_date
-      attribute :shared_item
-      attribute :own_item
-      attribute :amount_code
-      attribute :amount
-      attribute :document_number
-      attribute :reference_1
-      attribute :reference_2
-      attribute :additional_items, Array[AdditionalItem]
-      attribute :additional_currency, AdditionalCurrency
       def debit?; self.amount_code == DEBIT_CODE end
     end
   end
diff --git a/norma43_parser.gemspec b/norma43_parser.gemspec
index 054df4a..3e54d13 100644
--- a/norma43_parser.gemspec
+++ b/norma43_parser.gemspec
@@ -19,7 +19,6 @@ Gem::Specification.new do |spec|
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
   spec.require_paths = ["lib"]
 
-  spec.add_runtime_dependency "virtus",   "~> 1.0"
   spec.add_runtime_dependency "zeitwerk", "~> 2.0"
 
   spec.add_development_dependency "rake",  "~> 13.0"
diff --git a/spec/norma43/line_processors/account_end_spec.rb b/spec/norma43/line_processors/account_end_spec.rb
index 692eba9..9fd81ad 100644
--- a/spec/norma43/line_processors/account_end_spec.rb
+++ b/spec/norma43/line_processors/account_end_spec.rb
@@ -3,10 +3,7 @@
 module Norma43
   module LineProcessors
     RSpec.describe AccountEnd do
-      let :line do
-        double "Line", attributes: {}
-      end
-
+      let(:line) { instance_double(LineParsers::AccountEnd, attributes: {}) } 
       let(:account) { Norma43::Models::Account.new }
       let(:contexts) { Norma43::Utils::Contexts.new(
         [
diff --git a/spec/norma43/line_processors/account_start_spec.rb b/spec/norma43/line_processors/account_start_spec.rb
index 7a6799a..6741526 100644
--- a/spec/norma43/line_processors/account_start_spec.rb
+++ b/spec/norma43/line_processors/account_start_spec.rb
@@ -2,8 +2,8 @@
 
 module Norma43
   module LineProcessors
-    RSpec.describe "AccountStart" do
-      let(:line) { double "Line", attributes: {} }
+    RSpec.describe AccountStart do
+      let(:line) { instance_double(LineParsers::AccountStart, attributes: {}) }
       let(:document) { Norma43::Models::Document.new }
       let(:contexts) { Norma43::Utils::Contexts.new }
 
@@ -20,7 +20,7 @@ module LineProcessors
       end
 
       context "when AccountStart is called" do
-        let(:fake_account) { double "Norma43::Models::Account" }
+        let(:fake_account) { instance_double(Norma43::Models::Account) }
         before do
           allow(Norma43::Models::Account).to receive(:new) { fake_account }
         end
diff --git a/spec/norma43/line_processors/additional_currency_spec.rb b/spec/norma43/line_processors/additional_currency_spec.rb
index d9907fd..ec94038 100644
--- a/spec/norma43/line_processors/additional_currency_spec.rb
+++ b/spec/norma43/line_processors/additional_currency_spec.rb
@@ -2,8 +2,8 @@
 
 module Norma43
   module LineProcessors
-    RSpec.describe "AdditionalCurrency" do
-      let(:line) { double "Line", attributes: {} }
+    RSpec.describe AdditionalCurrency do
+      let(:line) { instance_double(LineParsers::AdditionalCurrency, attributes: {}) }
       let(:transaction) { Norma43::Models::Transaction.new }
       let(:contexts) { Norma43::Utils::Contexts.new(
         [
@@ -22,7 +22,7 @@ module LineProcessors
       end
 
       context "when AdditionalCurrency is called" do
-        let(:fake_additional_currency) { double "Models::AdditionalCurrency" }
+        let(:fake_additional_currency) { instance_double(Models::AdditionalCurrency) }
         before do
           allow(Models::AdditionalCurrency).to receive(:new) { fake_additional_currency }
         end
diff --git a/spec/norma43/line_processors/additional_items_spec.rb b/spec/norma43/line_processors/additional_item_spec.rb
similarity index 84%
rename from spec/norma43/line_processors/additional_items_spec.rb
rename to spec/norma43/line_processors/additional_item_spec.rb
index 70a9472..680c40e 100644
--- a/spec/norma43/line_processors/additional_items_spec.rb
+++ b/spec/norma43/line_processors/additional_item_spec.rb
@@ -2,8 +2,8 @@
 
 module Norma43
   module LineProcessors
-    RSpec.describe "AdditionalItems" do
-      let(:line) { double "Line", attributes: {} }
+    RSpec.describe AdditionalItem do
+      let(:line) { instance_double(LineParsers::AdditionalItem, attributes: {}) }
       let(:transaction) { Norma43::Models::Transaction.new }
       let(:contexts) { Norma43::Utils::Contexts.new(
         [
@@ -22,7 +22,7 @@ module LineProcessors
       end
 
       context "when AdditionalItem is called" do
-        let(:fake_additional_item) { double "Models::AdditionalItem" }
+        let(:fake_additional_item) { instance_double(Models::AdditionalItem) }
         before do
           allow(Models::AdditionalItem).to receive(:new) { fake_additional_item }
         end
diff --git a/spec/norma43/line_processors/document_end_spec.rb b/spec/norma43/line_processors/document_end_spec.rb
index 43b5e7f..942bc63 100644
--- a/spec/norma43/line_processors/document_end_spec.rb
+++ b/spec/norma43/line_processors/document_end_spec.rb
@@ -2,15 +2,12 @@
 
 module Norma43
   module LineProcessors
-    RSpec.describe "DocumentEnd" do
-      class Thing
-      end
-
-      let(:line) { double "Line", record_number: 35 }
+    RSpec.describe DocumentEnd do
+      let(:line) { instance_double(LineParsers::DocumentEnd, record_number: 35) }
 
       it "moves to the nearest document context" do
         document = Norma43::Models::Document.new
-        contexts = Norma43::Utils::Contexts.new [Thing.new, document, Thing.new, Thing.new]
+        contexts = Norma43::Utils::Contexts.new [anything, document, anything, anything]
 
         DocumentEnd.call line, contexts
 
diff --git a/spec/norma43/line_processors/document_start_spec.rb b/spec/norma43/line_processors/document_start_spec.rb
index 4103713..ae7ccde 100644
--- a/spec/norma43/line_processors/document_start_spec.rb
+++ b/spec/norma43/line_processors/document_start_spec.rb
@@ -2,8 +2,8 @@
 
 module Norma43
   module LineProcessors
-    RSpec.describe "DocumentStart" do
-      let (:line) { double "Line", attributes: {} }
+    RSpec.describe DocumentStart do
+      let(:line) { instance_double(LineParsers::DocumentStart, attributes: {}) }
 
       it "instantiates a new document with the line attributes" do
         allow(Models::Document).to receive :new
@@ -14,7 +14,7 @@ module LineProcessors
       end
 
       it "sets the document as the current context" do
-        fake_document = double "Models::Document"
+        fake_document = instance_double(Models::Document)
         allow(Models::Document).to receive(:new) { fake_document }
 
         contexts = DocumentStart.call line, Norma43::Utils::Contexts.new
diff --git a/spec/norma43/line_processors/transaction_spec.rb b/spec/norma43/line_processors/transaction_spec.rb
index 9758929..f0ef3ff 100644
--- a/spec/norma43/line_processors/transaction_spec.rb
+++ b/spec/norma43/line_processors/transaction_spec.rb
@@ -2,8 +2,8 @@
 
 module Norma43
   module LineProcessors
-    RSpec.describe "Transaction" do
-      let(:line) { double "Line", attributes: {} }
+    RSpec.describe Transaction do
+      let(:line) { instance_double(LineParsers::Transaction, attributes: {}) }
       let(:account) { Norma43::Models::Account.new }
       let(:contexts) { Norma43::Utils::Contexts.new(
         [
@@ -22,7 +22,7 @@ module LineProcessors
       end
 
       context "when Transaction is called" do
-        let(:fake_transaction) { double "Models::Transaction" }
+        let(:fake_transaction) { instance_double(Models::Transaction) }
         before do
           allow(Models::Transaction).to receive(:new) { fake_transaction }
         end
diff --git a/spec/norma43/models/account_spec.rb b/spec/norma43/models/account_spec.rb
index fbb74d4..b70ac37 100644
--- a/spec/norma43/models/account_spec.rb
+++ b/spec/norma43/models/account_spec.rb
@@ -3,17 +3,51 @@
 module Norma43
   module Models
     RSpec.describe Account do
+      it_behaves_like "a model"
+
       describe "#iban" do
-        it { is_expected.to respond_to :iban }
+        it { is_expected.to respond_to(:iban) }
 
         context "with the example in the documentation" do
-          it "delegates to SpanishIban to return a IBAN string" do
+          it "returns the correct IBAN string" do
             account = subject
-            allow(Account::SpanishIban).to receive(:from_account).with(account).and_return("ES0000000000000000000123")
-            expect(account.iban).to eq("ES0000000000000000000123")
-            expect(Account::SpanishIban).to have_received(:from_account).with(account)
+            account.account_number = 1234567
+            account.bank_code = 81
+            account.branch_code = 54
+
+            expect(account.iban).to eq("ES5400810054180001234567")
           end
         end
+
+        context "with missing bank data" do
+          subject { described_class.new.iban }
+          it { is_expected.to be_nil }
+        end
+
+        context "with missing bank code" do
+          subject { described_class.new(bank_code: nil, branch_code: 1234, account_number: 1234).iban }
+          it { is_expected.to be_nil }
+        end
+
+        context "with missing branch code" do
+          subject { described_class.new(bank_code: 1234, branch_code: nil, account_number: 1234).iban }
+          it { is_expected.to be_nil }
+        end
+
+        context "with missing account number" do
+          subject { described_class.new(bank_code: 1234, branch_code: 1234, account_number: nil).iban }
+          it { is_expected.to be_nil }
+        end
+
+        context "with negative account number" do
+          subject { described_class.new(bank_code: 1234, branch_code: 1234, account_number: -1234).iban }
+          it { is_expected.to be_nil }
+        end
+
+        context "with an account number which is too large" do
+          subject { described_class.new(bank_code: 1234, branch_code: 1234, account_number: 1*10**10).iban }
+          it { is_expected.to be_nil }
+        end
       end
     end
   end
diff --git a/spec/norma43/models/document_spec.rb b/spec/norma43/models/document_spec.rb
new file mode 100644
index 0000000..6757938
--- /dev/null
+++ b/spec/norma43/models/document_spec.rb
@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+module Norma43
+  module Models
+    RSpec.describe Document do
+      it_behaves_like "a model"
+
+      describe "#transaction_date" do
+        it { is_expected.to respond_to(:transaction_date) }
+
+        context "when there are no accounts" do
+          subject(:document) { described_class.new({ accounts: [] }) }
+
+          it { expect(document.transaction_date).to be_nil }
+        end
+
+        context "when there are accounts" do
+          subject(:document) { described_class.new({ accounts: [account] }) }
+
+          let(:account) {
+            Account.new(transactions: [
+              nil,
+              Transaction.new(transaction_date: nil),
+              Transaction.new(transaction_date: Date.parse("2024-01-23")),
+            ])
+          }
+
+          it "returns the date of the first account with a transaction date" do
+            expect(document.transaction_date).to eq(Date.parse("2024-01-23"))
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/spec/norma43/models/transaction_spec.rb b/spec/norma43/models/transaction_spec.rb
new file mode 100644
index 0000000..dc360e2
--- /dev/null
+++ b/spec/norma43/models/transaction_spec.rb
@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+module Norma43
+  module Models
+    RSpec.describe Transaction do
+      it_behaves_like "a model"
+
+      describe "#debit?" do
+        it { is_expected.to respond_to(:debit?) }
+
+        context "when amount code is code for debits" do
+          subject(:transaction) { described_class.new(amount_code: 1) }
+
+          it { expect(transaction.debit?).to be_truthy }
+        end
+
+        context "when amount code is code for credits" do
+          subject(:transaction) { described_class.new(amount_code: 2) }
+
+          it { expect(transaction.debit?).to be_falsey }
+        end
+      end
+    end
+  end
+end
diff --git a/spec/norma43_spec.rb b/spec/norma43_spec.rb
index 724071d..3207546 100644
--- a/spec/norma43_spec.rb
+++ b/spec/norma43_spec.rb
@@ -6,7 +6,7 @@
   describe "#parse" do
     it "returns the parser results" do
       text = "some total-in text"
-      parser = double "Parser", result: "result"
+      parser = instance_double(Norma43::Parser, result: "result")
       expect(Norma43::Parser).to receive(:new).with(text) { parser }
 
       expect(Norma43.parse(text)).to eq "result"
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index cbd8655..29f6ad3 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require "norma43"
+
 RSpec.configure do |config|
   config.order = :random
   Kernel.srand config.seed
@@ -11,6 +13,7 @@
   config.mock_with :rspec do |mocks|
     mocks.syntax = :expect
     mocks.verify_partial_doubles = true
+    mocks.verify_doubled_constant_names = true
   end
 end
 
diff --git a/spec/support/shared_examples_for_models.rb b/spec/support/shared_examples_for_models.rb
new file mode 100644
index 0000000..50d43e3
--- /dev/null
+++ b/spec/support/shared_examples_for_models.rb
@@ -0,0 +1,61 @@
+# frozen_string_literal: true
+
+RSpec.shared_examples "a model" do
+  it { is_expected.to respond_to(:attributes) }
+  it { is_expected.to respond_to(:attributes=) }
+  it { is_expected.to respond_to(:to_h) }
+  it { is_expected.to respond_to(:to_hash) }
+
+  describe "#new" do
+    subject(:model) { described_class.new(attributes) }
+
+    context "when instantiated with an empty hash" do
+      let(:attributes) { {} }
+
+      it "accepts it without failing" do
+        expect { model }.not_to raise_error
+      end
+    end
+  end
+
+  describe "#attributes" do
+    subject { described_class.new.attributes }
+
+    it { is_expected.not_to be_empty }
+    it { is_expected.to respond_to(:each_pair) }
+    it { is_expected.to respond_to(:to_h) }
+    it { is_expected.to respond_to(:to_hash) }
+    it { is_expected.to respond_to(:keys) }
+
+    describe "#attributes.keys" do
+      subject { super().keys }
+
+      it { is_expected.not_to be_empty }
+      it { is_expected.to all(be_a(Symbol)) }
+    end
+  end
+
+  describe "#attributes=" do
+    subject { described_class.new.attributes=(attributes) }
+
+    context "when passed an empty hash" do
+      let(:attributes) { {} }
+
+      it "accepts it without failing" do
+        expect { subject }.not_to raise_error
+      end
+    end
+
+    context "when passed a hash with unknown attribute names" do
+      let(:attributes) { { potato: nil } }
+
+      it "accepts it without failing" do
+        expect { subject }.not_to raise_error
+      end
+
+      it "does not set any new method" do
+        expect { subject.potato }.to raise_error(NoMethodError, /undefined method.+potato/i)
+      end
+    end
+  end
+end