Allow copying contents when they're not in the elements.yml (#2068)

When changing the elements.yml, we will often still have contents from
previous iterations of that file in the database. Copying must still
work.

app/models/alchemy/content/factory.rb

@@ -19,13 +19,13 @@ def new(attributes = {})
         return super if attributes.empty? || element.nil?
 
         definition = element.content_definition_for(attributes[:name])
-        if definition.blank?
+        if definition.blank? && attributes[:essence_type].nil?
           raise ContentDefinitionError, "No definition found in elements.yml for #{attributes.inspect} and #{element.inspect}"
         end
 
         super(
-          name: definition[:name],
-          essence_type: normalize_essence_type(definition[:type]),
+          name: attributes[:name],
+          essence_type: attributes[:essence_type] || normalize_essence_type(definition[:type]),
           element: element
         ).tap(&:build_essence)
       end
@@ -116,7 +116,7 @@ def definition
     # If an optional type is passed, this type of essence gets created.
     #
     def build_essence(attributes = {})
-      self.essence = essence_class(essence_type).new(
+      self.essence = essence_class.new(
         { content: self, ingredient: default_value }.merge(attributes)
       )
     end
@@ -132,12 +132,10 @@ def create_essence!(attrs = {})
 
     private
 
-    # Returns a class constant from definition's type field.
+    # Returns a class constant from definition's type field or the essence_type column
     #
-    # If an optional type is passed, this type of essence gets constantized.
-    #
-    def essence_class(type = nil)
-      Content.normalize_essence_type(type || definition["type"]).constantize
+    def essence_class
+      (essence_type || Content.normalize_essence_type(definition["type"])).constantize
     end
   end
 end

spec/models/alchemy/content_spec.rb

@@ -163,6 +163,18 @@ module Alchemy
         expect(subject.essence).to be_instance_of(EssenceText)
         expect(subject.essence).to_not be_persisted
       end
+
+      context "when given an essence_type attribute that is not in the definition" do
+        let(:arguments) { { element: element, essence_type: "Alchemy::EssenceText", name: "not_in_elements_yml" } }
+
+        subject { Content.new(arguments) }
+
+        it "does not raise an error" do
+          expect { subject }.not_to raise_exception
+          expect(subject.name).to eq("not_in_elements_yml")
+          expect(subject.essence).to be_a(Alchemy::EssenceText)
+        end
+      end
     end
 
     describe ".create" do