feat: refactor player and album relationship to many-to-many

[flaviolpgjr]

Importante

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Descrição

Este PR realiza o refactoring do relacionamento entre Player e Album, alterando de 1:N para N:N.

Principais mudanças:

• Criação da tabela de junção player_albums
• Migração dos dados existentes para preservar os vínculos atuais
• Remoção da coluna player_id de albums
• Ajuste dos models para relacionamento many-to-many
• Inclusão de validação para evitar duplicidade
• Atualização de testes e fixtures

A mudança foi feita em etapas para garantir consistência dos dados e compatibilidade durante a transição.

Issue tracker

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Code Review

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CONTRIBUTING.md

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[Copilot]

Pull request overview

Refactors the domain relationship between Player and Album from 1:N to N:N by introducing a join model/table (player_albums), migrating existing associations, and updating models/tests/docs to reflect the new many-to-many structure.

Changes:

• Added player_albums join table + PlayerAlbum model with uniqueness constraint.
• Backfilled existing albums.player_id data into player_albums and removed player_id from albums.
• Updated model associations, fixtures, and Minitest coverage; expanded README and adjusted mimemagic dependency.

Reviewed changes

Copilot reviewed 15 out of 16 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
app/models/player.rb	Replaces direct has_many :albums with has_many :albums, through: :player_albums.
app/models/album.rb	Replaces belongs_to :player with has_many :players, through: :player_albums.
app/models/player_album.rb	Introduces join model and uniqueness validation.
db/migrate/20260414125603_create_player_albums.rb	Creates player_albums table and unique composite index.
db/migrate/20260414125631_migrate_album_player_to_player_albums.rb	Migrates existing album-player links into the join table.
db/migrate/20260414131544_remove_player_id_from_albums.rb	Removes the old player_id reference from albums.
db/schema.rb	Updates schema to reflect the new join table and removed column.
test/models/player_test.rb	Adds coverage asserting a player can have many albums.
test/models/album_test.rb	Updates validity expectations and asserts an album can have many players.
test/models/player_album_test.rb	Adds join model validation tests (presence + uniqueness).
test/fixtures/players.yml	Adds madonna fixture.
test/fixtures/albums.yml	Removes per-album player association and adds a collab album.
test/fixtures/player_albums.yml	Adds join fixtures linking players and albums.
README.md	Documents the refactor approach, rationale, and how to run/tests.
Gemfile	Pins mimemagic to restore installability.
Gemfile.lock	Updates mimemagic resolution and dependencies.

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[Copilot]

This data migration references the application models (Album/PlayerAlbum) directly. Migrations should avoid depending on app models because future refactors (renames, validations/callback changes, default scopes) can cause db:migrate to fail on fresh setups. Consider defining lightweight migration-local models (e.g., Class.new(ActiveRecord::Base) with self.table_name = ...) or using SQL/insert_all to backfill the join table.

Suggested change

	def up
	Album.reset_column_information
	Album.where.not(player_id: nil).find_each do |album|
	PlayerAlbum.find_or_create_by!(
	class MigrationAlbum < ActiveRecord::Base
	self.table_name = "albums"
	end
	class MigrationPlayerAlbum < ActiveRecord::Base
	self.table_name = "player_albums"
	end
	def up
	MigrationAlbum.reset_column_information
	MigrationPlayerAlbum.reset_column_information
	MigrationAlbum.where.not(player_id: nil).find_each do |album|
	MigrationPlayerAlbum.find_or_create_by!(

[Copilot]

The Gemfile consistently uses single-quoted strings, but this new gem declaration uses double quotes. For consistency with the existing style in this file, switch this line to single quotes.

Suggested change

	gem "mimemagic", "~> 0.3.10"
	gem 'mimemagic', '~> 0.3.10'