Added tests on custom foreign key

spec/chrono_model/time_machine/history_spec.rb

@@ -58,12 +58,18 @@
       subject(:historical_foo) { Foo::History.find(last_foo.hid) }
 
       let(:last_foo) { Foo.history.last }
+      let!(:tar1) { Tar.create(foo: last_foo)}
 
       it { is_expected.to eq last_foo }
 
       it 'preserves associations' do
         expect(historical_foo.bars).to eq last_foo.bars
       end
+
+      it 'preserves associations that are using a different fkid' do
+        expect(historical_foo.tars).not_to be_empty
+        expect(historical_foo.tars).to eq(last_foo.tars)
+      end
     end
 
     context '.sorted' do

spec/support/time_machine/structure.rb

@@ -46,6 +46,18 @@ module ChronoTest::TimeMachine
     t.string     :name
     t.integer    :fooity
     t.references :goo
+    t.string     :refee_foo
+  end
+
+  adapter.create_table 'tars', temporal: true do |t|
+    t.string     :name
+    t.string     :foo_refering
+  end
+
+  adapter.change_table 'tars', temporal: true do
+    def up
+      add_reference :foos, column: :foo_refering, primary_key: :refee_foo
+    end
   end
 
   adapter.create_table 'moos', temporal: true do |t|
@@ -80,6 +92,15 @@ class ::Baz < ActiveRecord::Base
     has_timeline with: :bar
   end
 
+  class ::Tar < ActiveRecord::Base
+    include ChronoModel::TimeGate
+
+    belongs_to :foo, foreign_key: :foo_refering, primary_key: :refee_foo, class_name: 'Foo'
+
+    has_timeline with: :foo
+  end
+
+
   class ::Boo < ActiveRecord::Base
     include ChronoModel::TimeMachine
 
@@ -90,6 +111,7 @@ class ::Foo < ActiveRecord::Base
     include ChronoModel::TimeMachine
 
     has_many :bars
+    has_many :tars, foreign_key: :foo_refering, primary_key: :refee_foo
     has_many :sub_bars, through: :bars
     has_many :sub_sub_bars, through: :sub_bars