Rails Model Generator

Before writing code, define the model:

## Model: [ModelName]

### Table: [table_name]

### Attributes
| Name | Type | Constraints | Default |
|------|------|-------------|---------|
| name | string | required, unique | - |
| email | string | required, unique, email format | - |
| status | integer | enum | 0 (pending) |
| organization_id | bigint | foreign key | - |

### Associations
- belongs_to :organization
- has_many :posts, dependent: :destroy
- has_one :profile, dependent: :destroy

### Validations
- name: presence, uniqueness, length(max: 100)
- email: presence, uniqueness, format(email)
- status: inclusion in enum values

### Scopes
- active: status = active
- recent: ordered by created_at desc
- by_organization(org): where organization_id = org.id

### Instance Methods
- full_name: combines first_name and last_name
- active?: checks if status is active

### Callbacks
- before_save :normalize_email
- after_create :send_welcome_email

Step 2: Create Model Test

Location: test/models/[model_name]_test.rb

# frozen_string_literal: true

require "test_helper"

class ModelNameTest < ActiveSupport::TestCase
  # === Associations ===
  test "belongs to organization" do
    model = model_names(:one)
    assert_respond_to model, :organization
    assert_instance_of Organization, model.organization
  end

  test "has many posts" do
    model = model_names(:one)
    assert_respond_to model, :posts
  end

  # === Validations ===
  test "requires name" do
    model = ModelName.new(name: nil)
    assert_not model.valid?
    assert_includes model.errors[:name], "can't be blank"
  end

  test "requires unique email (case insensitive)" do
    existing = model_names(:one)
    model = ModelName.new(email: existing.email.upcase)
    assert_not model.valid?
    assert_includes model.errors[:email], "has already been taken"
  end

  test "validates name length max 100" do
    model = ModelName.new(name: "a" * 101)
    assert_not model.valid?
    assert model.errors[:name].any? { |e| e.include?("too long") }
  end

  # === Scopes ===
  test ".active returns only active records" do
    active_record = model_names(:active_one)
    inactive_record = model_names(:inactive_one)

    results = ModelName.active
    assert_includes results, active_record
    assert_not_includes results, inactive_record
  end

  # === Instance Methods ===
  test "#full_name returns combined name" do
    model = ModelName.new(first_name: "John", last_name: "Doe")
    assert_equal "John Doe", model.full_name
  end
end

Step 3: Create Fixtures

Location: test/fixtures/[model_name_plural].yml

# test/fixtures/model_names.yml