Enhance validations and add tests for organisation name changes

app/models/organisation_name_change.rb

@@ -5,8 +5,8 @@ class OrganisationNameChange < ApplicationRecord
   scope :before_date, ->(date) { where("startdate < ?", date) }
   scope :after_date, ->(date) { where("startdate > ?", date) }
 
-  validates :name, presence: true
-  validates :startdate, presence: true, unless: -> { immediate_change }
+  validates :name, presence: { message: "New name is required and cannot be left blank." }
+  validates :startdate, presence: { message: "Start date must be provided unless this is an immediate change." }, unless: -> { immediate_change }
   validate :startdate_must_be_after_last_change
   validate :name_must_be_different_from_current
   validate :startdate_must_be_unique_for_organisation

spec/factories/organisation_name_change.rb

@@ -3,7 +3,7 @@ FactoryBot.define do
     association :organisation
     name { "#{Faker::Name.name} Housing Org" }
     immediate_change { true }
-    startdate { Time.zone.now }
+    startdate { Time.zone.tomorrow }
     change_type { :user_change }
 
     trait :future_change do

spec/models/organisation_name_change_spec.rb

@@ -0,0 +1,96 @@
+require "rails_helper"
+
+RSpec.describe OrganisationNameChange, type: :model do
+  let(:organisation) { create(:organisation) }
+
+  describe "validations" do
+    it "is valid with valid attributes" do
+      name_change = build(:organisation_name_change, organisation:)
+      expect(name_change).to be_valid
+    end
+
+    it "is invalid without a name" do
+      name_change = build(:organisation_name_change, organisation:, name: nil)
+      expect(name_change).not_to be_valid
+      expect(name_change.errors[:name]).to include("New name is required and cannot be left blank.")
+    end
+
+    it "is invalid without a startdate if not immediate" do
+      name_change = build(:organisation_name_change, organisation:, startdate: nil, immediate_change: false)
+      expect(name_change).not_to be_valid
+      expect(name_change.errors[:startdate]).to include("Start date must be provided unless this is an immediate change.")
+    end
+
+    it "is invalid if startdate is not unique for the organisation" do
+      create(:organisation_name_change, organisation:, startdate: Time.zone.tomorrow)
+      name_change = build(:organisation_name_change, organisation:, immediate_change: false, startdate: Time.zone.tomorrow)
+      expect(name_change).not_to be_valid
+      expect(name_change.errors[:startdate]).to include("Start date cannot be the same as another name change.")
+    end
+
+    it "is invalid if name is the same as the current name on the change date" do
+      create(:organisation_name_change, organisation:, name: "New Name", startdate: 1.day.ago)
+      name_change = build(:organisation_name_change, organisation:, name: "New Name", startdate: Time.zone.now)
+      expect(name_change).not_to be_valid
+      expect(name_change.errors[:name]).to include("New name must be different from the current name on the change date.")
+    end
+
+    it "is invalid if startdate is after the organisation's merge date" do
+      organisation.update!(merge_date: Time.zone.now)
+      name_change = build(:organisation_name_change, organisation:, immediate_change: false, startdate: Time.zone.tomorrow)
+      expect(name_change).not_to be_valid
+      expect(name_change.errors[:startdate]).to include("Start date must be earlier than the organisation's merge date (#{organisation.merge_date.to_formatted_s(:govuk_date)}). You cannot make changes to the name of an organisation after it has merged.")
+    end
+  end
+
+  describe "scopes" do
+    let!(:visible_change) { create(:organisation_name_change, :future_change, organisation:) }
+    let!(:discarded_change) { create(:organisation_name_change, organisation:, discarded_at: Time.zone.now) }
+
+    it "returns only visible changes" do
+      expect(described_class.visible).to include(visible_change)
+      expect(described_class.visible).not_to include(discarded_change)
+    end
+
+    it "returns changes before a specific date" do
+      name_change = create(:organisation_name_change, organisation:, startdate: 1.day.ago)
+      expect(described_class.before_date(Time.zone.now)).to include(name_change)
+    end
+
+    it "returns changes after a specific date" do
+      name_change = create(:organisation_name_change, organisation:, startdate: 2.days.from_now)
+      expect(described_class.after_date(Time.zone.now)).to include(name_change)
+    end
+  end
+
+  describe "#status" do
+    it "returns 'scheduled' if the startdate is in the future" do
+      name_change = build(:organisation_name_change, organisation:, startdate: 1.day.from_now)
+      expect(name_change.status).to eq("scheduled")
+    end
+
+    it "returns 'active' if the startdate is today or in the past and end_date is nil or in the future" do
+      name_change = build(:organisation_name_change, organisation:, startdate: 1.day.ago)
+      expect(name_change.status).to eq("active")
+    end
+
+    it "returns 'inactive' if the end_date is in the past" do
+      name_change = create(:organisation_name_change, organisation:, startdate: 2.days.ago)
+      allow(name_change).to receive(:end_date).and_return(1.day.ago)
+      expect(name_change.status).to eq("inactive")
+    end
+  end
+
+  describe "#includes_date?" do
+    it "returns true if the date is within the change period" do
+      name_change = create(:organisation_name_change, organisation:, startdate: 1.day.ago)
+      expect(name_change.includes_date?(Time.zone.now)).to be true
+    end
+
+    it "returns false if the date is outside the change period" do
+      name_change = create(:organisation_name_change, organisation:, startdate: 2.days.ago)
+      create(:organisation_name_change, organisation:, startdate: 1.day.from_now)
+      expect(name_change.includes_date?(2.days.from_now)).to be false
+    end
+  end
+end