Add basic invitations

spec/models/invitation_spec.rb

@@ -0,0 +1,22 @@
+require 'rails_helper'
+
+RSpec.describe Invitation, type: :model do
+  let(:user) { build :user }
+
+  describe "tokens" do
+    it "requires a user" do
+      expect { Invitation.create! }.to raise_error(ActiveRecord::RecordInvalid)
+    end
+
+    it "generates a random token when created" do
+      invitation = Invitation.new(user: user)
+      invitation.save!
+      token = invitation.token
+      expect(token).to be_a(String)
+      expect(token.length).to eq(16)
+
+      invitation_2 = Invitation.create(user: user)
+      expect(token).not_to eq(invitation_2.token)
+    end
+  end
+end