Add full STI support (inherit snapshot children definition from base class, and allow overriding in STI child classes)

Author: foobear

lib/active_snapshot/models/concerns/snapshots_concern.rb

@@ -6,6 +6,8 @@ module SnapshotsConcern
       ### We do NOT mark these as dependent: :destroy, the developer must manually destroy the snapshots or individual snapshot items
       has_many :snapshots, as: :item, class_name: 'ActiveSnapshot::Snapshot'
       has_many :snapshot_items, as: :item, class_name: 'ActiveSnapshot::SnapshotItem'
+
+      class_attribute :snapshot_children_proc
     end
 
     def create_snapshot!(identifier: nil, user: nil, metadata: nil)
@@ -25,9 +27,9 @@ def create_snapshot!(identifier: nil, user: nil, metadata: nil)
 
       def has_snapshot_children(&block)
         if block_given?
-          @snapshot_children_proc = block
+          self.snapshot_children_proc = block
         else
-          @snapshot_children_proc
+          self.snapshot_children_proc
         end
       end
 

test/dummy_app/app/models/sub_post.rb

@@ -1,11 +1,3 @@
 class SubPost < Post
-  has_snapshot_children do
-    instance = self.class.includes(:comments, :notes).find(id)
-
-    {
-      comments: instance.comments,
-      notes: instance.notes,
-      nil_assoc: nil,
-    }
-  end
+  # Inherits snapshot children definition from base class
 end

test/dummy_app/app/models/sub_post_with_own_definition.rb

@@ -0,0 +1,6 @@
+class SubPostWithOwnDefinition < Post
+  # Ignores snapshot children definition from base class, and defines its own
+  has_snapshot_children do
+    { comments: comments }
+  end
+end

test/models/snapshot_test.rb

@@ -181,17 +181,68 @@ def test_fetch_reified_items_without_readonly
     assert children_hash.values.all?(&:readonly?)
   end
 
+  def test_fetch_reified_items_with_base_class
+    post = Post.create!(a: 1, b: 2)
+
+    comment_content = 'Example comment'
+    post.comments.create!(content: comment_content)
+
+    note_body = 'Example note'
+    post.notes.create!(body: note_body)
+
+    post.create_snapshot!(identifier: 'v1')
+    snapshot = post.snapshots.first
+
+    reified_post, reified_children = snapshot.fetch_reified_items
+
+    assert_equal post, reified_post
+    assert reified_post.readonly?
+    assert_equal ['comments', 'notes'], reified_children.keys.sort
+    assert_equal comment_content, reified_children['comments'].first.content
+    assert_equal note_body, reified_children['notes'].first.body
+  end
+
   def test_fetch_reified_items_with_sti_class
+    # Inherits snapshot children definition from base class
     post = SubPost.create!(a: 1, b: 2)
+
     comment_content = 'Example comment'
     post.comments.create!(content: comment_content)
+
+    note_body = 'Example note'
+    post.notes.create!(body: note_body)
+
     post.create_snapshot!(identifier: 'v1')
     snapshot = post.snapshots.first
-    reified_items = snapshot.fetch_reified_items
 
-    assert_equal post, reified_items.first
-    assert reified_items.first.readonly?
-    assert_equal comment_content, reified_items.second[:comments].first.content
+    reified_post, reified_children = snapshot.fetch_reified_items
+
+    assert_equal post, reified_post
+    assert reified_post.readonly?
+    assert_equal ['comments', 'notes'], reified_children.keys.sort
+    assert_equal comment_content, reified_children['comments'].first.content
+    assert_equal note_body, reified_children['notes'].first.body
+  end
+
+  def test_fetch_reified_items_with_sti_class_having_own_definition
+    # Includes "comments" children, but no "notes"
+    post = SubPostWithOwnDefinition.create!(a: 1, b: 2)
+
+    comment_content = 'Example comment'
+    post.comments.create!(content: comment_content)
+
+    note_body = 'Example note'
+    post.notes.create!(body: note_body)
+
+    post.create_snapshot!(identifier: 'v1')
+    snapshot = post.snapshots.first
+
+    reified_post, reified_children = snapshot.fetch_reified_items
+
+    assert_equal post, reified_post
+    assert reified_post.readonly?
+    assert_equal ['comments'], reified_children.keys
+    assert_equal comment_content, reified_children['comments'].first.content
   end
 
   def test_fetch_reified_items_handles_dropped_columns!

test/models/snapshots_concern_test.rb

@@ -58,7 +58,7 @@ def test_has_snapshot_children
       {}
     end
 
-    assert klass.instance_variable_get(:@snapshot_children_proc).is_a?(Proc)
+    assert klass.has_snapshot_children.is_a?(Proc)
 
     klass.new.children_to_snapshot