Adds nickname-related validations & name to User

app/models/user.rb

@@ -2,7 +2,11 @@ class User < ActiveRecord::Base
   devise :database_authenticatable, :registerable, :confirmable,
          :recoverable, :rememberable, :trackable, :validatable
 
+  validates :first_name, presence: true, unless: :use_nickname?
+  validates :last_name, presence: true, unless: :use_nickname?
+  validates :nickname, presence: true, if: :use_nickname?
+
   def name
-    "#{first_name} #{last_name}"
+    use_nickname? ? nickname : "#{first_name} #{last_name}"
   end
 end

spec/models/user_spec.rb

@@ -1,4 +1,50 @@
 require 'rails_helper'
 
 describe User do
+  subject { build(:user) }
+
+  it "is valid" do
+    expect(subject).to be_valid
+  end
+
+  describe 'use_nickname' do
+    describe 'when true' do
+      before { subject.use_nickname = true }
+
+      it "activates the validation of nickname" do
+        subject.nickname = nil
+        expect(subject).to_not be_valid
+
+        subject.nickname = "dredd"
+        expect(subject).to be_valid
+      end
+
+      it "calculates the name using the nickname" do
+        subject.nickname = "dredd"
+        expect(subject.name).to eq("dredd")
+      end
+    end
+
+    describe 'when false' do
+      before { subject.use_nickname = false }
+
+      it "activates the validation of first_name and last_name" do
+        subject.first_name = nil
+        subject.last_name = nil
+        expect(subject).to_not be_valid
+
+        subject.first_name = "Joseph"
+        subject.last_name = "Dredd"
+        expect(subject).to be_valid
+      end
+
+      it "calculates the name using first_name and last_name" do
+        subject.first_name = "Joseph"
+        subject.last_name = "Dredd"
+        expect(subject.name).to eq("Joseph Dredd")
+      end
+    end
+  end
+
+
 end