Add model RelationStatus#transitions

app/models/relation_status.rb

@@ -4,6 +4,16 @@ class RelationStatus < ApplicationRecord
   CODENAME_RE = /\A[a-z][a-z0-9]*(_[a-z0-9]+)*\z/.freeze
   FORMAT_RE = /\A[^[:space:]]+(.*[^[:space:]]+)?\z/.freeze
 
+  ################
+  # Associations #
+  ################
+
+  has_many :transitions,
+           class_name: 'RelationTransition',
+           inverse_of: :from_status,
+           foreign_key: :from_status_id,
+           dependent: :restrict_with_exception
+
   ###############
   # Validations #
   ###############

app/models/relation_transition.rb

@@ -9,6 +9,7 @@ class RelationTransition < ApplicationRecord
 
   belongs_to :from_status,
              class_name: 'RelationStatus',
+             inverse_of: :transitions,
              optional: true
 
   belongs_to :to_status,

spec/models/relation_status_spec.rb

@@ -11,6 +11,16 @@ RSpec.describe RelationStatus do
     end
   end
 
+  describe '#transitions' do
+    it do
+      is_expected.to \
+        have_many(:transitions)
+        .class_name('RelationTransition')
+        .inverse_of(:from_status)
+        .dependent(:restrict_with_exception)
+    end
+  end
+
   describe '#codename' do
     def allow_value(*)
       super.for :codename

spec/models/relation_transition_spec.rb

@@ -8,7 +8,10 @@ RSpec.describe RelationTransition do
   describe '#from_status' do
     it do
       is_expected.to \
-        belong_to(:from_status).class_name('RelationStatus').optional
+        belong_to(:from_status)
+        .class_name('RelationStatus')
+        .inverse_of(:transitions)
+        .optional
     end
 
     it { is_expected.not_to validate_presence_of :from_status }