Add GameTrasactions (Start/End)

This allows us to track which User started a Game and which users made
the final winning/losing move to end a Game.

Also, fix an inconsistency in the test fixtures where the Game with
Status "Standing By" had a `started_at` value.

app/models/transactions/game_end_transaction.rb

@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+# GameEndTransaction is a {GameTransaction} marking which {User} made the final
+# move during the associated {Game}.
+class GameEndTransaction < GameTransaction
+end

app/models/transactions/game_start_transaction.rb

@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+# GameStartTransaction is a {GameTransaction} marking which {User} started the
+# associated {Game}.
+class GameStartTransaction < GameTransaction
+end

app/models/transactions/game_transaction.rb

@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+# GameTransaction records events transacted by {User}s on a {Game} and when they
+# occurred.
+#
+# @attr type [String] The Subclass name.
+# @attr user_id [Integer] References the {User} involved in this Transaction.
+# @attr game_id [Integer] References the {Game} involved in this Transaction.
+# @attr created_at [DateTime] When this Transaction occurred.
+class GameTransaction < ApplicationRecord
+  self.implicit_order_column = "created_at"
+
+  include AbstractBaseClassBehaviors
+  include ConsoleBehaviors
+
+  as_abstract_class
+
+  belongs_to :user
+  belongs_to :game
+
+  scope :for_user, ->(user) { where(user:) }
+  scope :for_game, ->(game) { where(game:) }
+
+  validates :game, uniqueness: { scope: :type }
+
+  def self.create_between(user:, game:)
+    new(user:, game:).tap(&:save!)
+  end
+
+  def self.exists_between?(user:, game:)
+    for_user(user).for_game(game).exists?
+  end
+
+  # GameTransaction::Console acts like a {GameTransaction} but otherwise handles
+  # IRB Console-specific methods/logic.
+  class Console
+    include ConsoleObjectBehaviors
+
+    private
+
+    def inspect_info
+      [
+        [user.inspect, game.inspect].join(" -> "),
+        I18n.l(created_at, format: :debug),
+      ].join(" @ ")
+    end
+  end
+end

db/migrate/20241112041937_create_game_transactions.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+# Version: 20241112041937
+class CreateGameTransactions < ActiveRecord::Migration[8.0]
+  def change
+    create_table(:game_transactions) do |t|
+      t.string(:type, null: false, index: true)
+      t.references(
+        :user, type: :uuid, foreign_key: { on_delete: :nullify }, index: true)
+      t.references(
+        :game, null: false, foreign_key: { on_delete: :cascade })
+
+      t.datetime(:created_at, null: false, index: true)
+    end
+
+    add_index(:game_transactions, %i[game_id type], unique: true)
+  end
+end

db/structure.sql

@@ -136,6 +136,38 @@ CREATE SEQUENCE public.cells_id_seq
 ALTER SEQUENCE public.cells_id_seq OWNED BY public.cells.id;
 
 
+--
+-- Name: game_transactions; Type: TABLE; Schema: public; Owner: -
+--
+
+CREATE TABLE public.game_transactions (
+    id bigint NOT NULL,
+    type character varying NOT NULL,
+    user_id uuid,
+    game_id bigint NOT NULL,
+    created_at timestamp(6) with time zone NOT NULL
+);
+
+
+--
+-- Name: game_transactions_id_seq; Type: SEQUENCE; Schema: public; Owner: -
+--
+
+CREATE SEQUENCE public.game_transactions_id_seq
+    START WITH 1
+    INCREMENT BY 1
+    NO MINVALUE
+    NO MAXVALUE
+    CACHE 1;
+
+
+--
+-- Name: game_transactions_id_seq; Type: SEQUENCE OWNED BY; Schema: public; Owner: -
+--
+
+ALTER SEQUENCE public.game_transactions_id_seq OWNED BY public.game_transactions.id;
+
+
 --
 -- Name: games; Type: TABLE; Schema: public; Owner: -
 --
@@ -250,6 +282,13 @@ ALTER TABLE ONLY public.cell_transactions ALTER COLUMN id SET DEFAULT nextval('p
 ALTER TABLE ONLY public.cells ALTER COLUMN id SET DEFAULT nextval('public.cells_id_seq'::regclass);
 
 
+--
+-- Name: game_transactions id; Type: DEFAULT; Schema: public; Owner: -
+--
+
+ALTER TABLE ONLY public.game_transactions ALTER COLUMN id SET DEFAULT nextval('public.game_transactions_id_seq'::regclass);
+
+
 --
 -- Name: games id; Type: DEFAULT; Schema: public; Owner: -
 --
@@ -296,6 +335,14 @@ ALTER TABLE ONLY public.cells
     ADD CONSTRAINT cells_pkey PRIMARY KEY (id);
 
 
+--
+-- Name: game_transactions game_transactions_pkey; Type: CONSTRAINT; Schema: public; Owner: -
+--
+
+ALTER TABLE ONLY public.game_transactions
+    ADD CONSTRAINT game_transactions_pkey PRIMARY KEY (id);
+
+
 --
 -- Name: games games_pkey; Type: CONSTRAINT; Schema: public; Owner: -
 --
@@ -426,6 +473,41 @@ CREATE INDEX index_cells_on_mine ON public.cells USING btree (mine);
 CREATE INDEX index_cells_on_revealed ON public.cells USING btree (revealed);
 
 
+--
+-- Name: index_game_transactions_on_created_at; Type: INDEX; Schema: public; Owner: -
+--
+
+CREATE INDEX index_game_transactions_on_created_at ON public.game_transactions USING btree (created_at);
+
+
+--
+-- Name: index_game_transactions_on_game_id; Type: INDEX; Schema: public; Owner: -
+--
+
+CREATE INDEX index_game_transactions_on_game_id ON public.game_transactions USING btree (game_id);
+
+
+--
+-- Name: index_game_transactions_on_game_id_and_type; Type: INDEX; Schema: public; Owner: -
+--
+
+CREATE UNIQUE INDEX index_game_transactions_on_game_id_and_type ON public.game_transactions USING btree (game_id, type);
+
+
+--
+-- Name: index_game_transactions_on_type; Type: INDEX; Schema: public; Owner: -
+--
+
+CREATE INDEX index_game_transactions_on_type ON public.game_transactions USING btree (type);
+
+
+--
+-- Name: index_game_transactions_on_user_id; Type: INDEX; Schema: public; Owner: -
+--
+
+CREATE INDEX index_game_transactions_on_user_id ON public.game_transactions USING btree (user_id);
+
+
 --
 -- Name: index_games_on_bbbv; Type: INDEX; Schema: public; Owner: -
 --
@@ -526,6 +608,14 @@ ALTER TABLE ONLY public.cell_transactions
     ADD CONSTRAINT fk_rails_8ae22ea0ff FOREIGN KEY (cell_id) REFERENCES public.cells(id) ON DELETE CASCADE;
 
 
+--
+-- Name: game_transactions fk_rails_adddf1bd52; Type: FK CONSTRAINT; Schema: public; Owner: -
+--
+
+ALTER TABLE ONLY public.game_transactions
+    ADD CONSTRAINT fk_rails_adddf1bd52 FOREIGN KEY (game_id) REFERENCES public.games(id) ON DELETE CASCADE;
+
+
 --
 -- Name: cell_transactions fk_rails_baaa458a22; Type: FK CONSTRAINT; Schema: public; Owner: -
 --
@@ -534,6 +624,14 @@ ALTER TABLE ONLY public.cell_transactions
     ADD CONSTRAINT fk_rails_baaa458a22 FOREIGN KEY (user_id) REFERENCES public.users(id) ON DELETE SET NULL;
 
 
+--
+-- Name: game_transactions fk_rails_c020c31c6a; Type: FK CONSTRAINT; Schema: public; Owner: -
+--
+
+ALTER TABLE ONLY public.game_transactions
+    ADD CONSTRAINT fk_rails_c020c31c6a FOREIGN KEY (user_id) REFERENCES public.users(id) ON DELETE SET NULL;
+
+
 --
 -- Name: cells fk_rails_d04db06fd5; Type: FK CONSTRAINT; Schema: public; Owner: -
 --
@@ -549,6 +647,7 @@ ALTER TABLE ONLY public.cells
 SET search_path TO "$user", public;
 
 INSERT INTO "schema_migrations" (version) VALUES
+('20241112041937'),
 ('20240927195322'),
 ('20240912030247'),
 ('20240911180310'),

test/fixtures/game_transactions.yml

@@ -0,0 +1,17 @@
+win1_game_start_transaction:
+  type: GameStartTransaction
+  user: user1
+  game: win1
+win1_game_end_transaction:
+  type: GameEndTransaction
+  user: user1
+  game: win1
+
+loss1_game_start_transaction:
+  type: GameStartTransaction
+  user: user1
+  game: loss1
+loss1_game_end_transaction:
+  type: GameEndTransaction
+  user: user2
+  game: loss1

test/fixtures/games.yml

@@ -11,9 +11,8 @@ loss1:
   <<: *DEFAULTS
   status: <%= Game.status_mines_win %>
   started_at: <%= 30.seconds.ago %>
-  ended_at: <%= 10.second.ago %>
+  ended_at: <%= 10.seconds.ago %>
 
 standing_by1:
   <<: *DEFAULTS
   status: <%= Game.status_standing_by %>
-  started_at: <%= Time.current %>

test/models/game_test.rb

@@ -27,7 +27,10 @@ class GameTest < ActiveSupport::TestCase
 
         context "GIVEN a Game#on? = true Game doesn't exist" do
           context "GIVEN a recently-ended Game exists" do
-            before { recently_ended_game.end_in_victory }
+            before do
+              recently_ended_game.touch(:started_at)
+              recently_ended_game.end_in_victory
+            end
 
             let(:recently_ended_game) { standing_by1 }
 

test/models/game_transaction_test.rb

@@ -0,0 +1,79 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+class GameTransactionTest < ActiveSupport::TestCase
+  describe "GameTransaction" do
+    let(:unit_class) { GameTransaction }
+
+    let(:user1) { users(:user1) }
+    let(:user2) { users(:user2) }
+
+    let(:win1) { games(:win1) }
+    let(:standing_by1) { games(:standing_by1) }
+
+    describe "DB insertion (GIVEN no Rails validation)" do
+      subject { GameStartTransaction.new(user: user1, game: win1) }
+
+      it "raises ActiveRecord::RecordNotUnique" do
+        exception =
+          _(-> {
+            subject.save(validate: false)
+          }).must_raise(ActiveRecord::RecordNotUnique)
+
+        _(exception.message).must_include(
+          "PG::UniqueViolation: ERROR:  "\
+          "duplicate key value violates unique constraint "\
+          '"index_game_transactions_on_game_id_and_type"')
+      end
+    end
+
+    describe ".create_between" do
+      context "GIVEN a new, unique pair" do
+        subject { GameStartTransaction }
+
+        it "creates the expected GameTransaction record, and returns it" do
+          result =
+            _(-> {
+              subject.create_between(user: user2, game: standing_by1)
+            }).must_change("GameTransaction.count")
+          _(result).must_be_instance_of(subject)
+          _(result.user).must_be_same_as(user2)
+          _(result.game).must_be_same_as(standing_by1)
+        end
+      end
+
+      context "GIVEN an existing, non-unique pair" do
+        subject { [GameStartTransaction, GameEndTransaction].sample }
+
+        it "raises ActiveRecord::RecordInvalid" do
+          exception =
+            _(-> {
+              subject.create_between(user: user1, game: win1)
+            }).must_raise(ActiveRecord::RecordInvalid)
+
+          _(exception.message).must_equal(
+            "Validation failed: Game has already been taken")
+        end
+      end
+    end
+
+    describe ".exists_between?" do
+      subject { unit_class }
+
+      context "GIVEN an existing pair" do
+        it "returns true" do
+          result = subject.exists_between?(user: user1, game: win1)
+          _(result).must_equal(true)
+        end
+      end
+
+      context "GIVEN a non-existent pair" do
+        it "returns false" do
+          result = subject.exists_between?(user: user2, game: win1)
+          _(result).must_equal(false)
+        end
+      end
+    end
+  end
+end