fix: build_stubbed timestamps are different (#1653)

Factories on entities with created_at and updated_at assign a slightly
different time for each, because it calls Time.now twice.

This fix ensures they will be assigned the exact same time.

Author: kimesf

lib/factory_bot/strategy/stub.rb

@@ -102,12 +102,14 @@ def clear_changes_information(result_instance)
       end
 
       def set_timestamps(result_instance)
+        timestamp = Time.current
+
         if missing_created_at?(result_instance)
-          result_instance.created_at = Time.current
+          result_instance.created_at = timestamp
         end
 
         if missing_updated_at?(result_instance)
-          result_instance.updated_at = Time.current
+          result_instance.updated_at = timestamp
         end
       end
 

spec/acceptance/stub_spec.rb

@@ -29,6 +29,24 @@
   end
 end
 
+describe "a stubbed instance with timestamps" do
+  include FactoryBot::Syntax::Methods
+
+  before do
+    define_model("ModelWithTimestamps", created_at: :datetime, updated_at: :datetime)
+
+    FactoryBot.define do
+      factory :model_with_timestamps
+    end
+  end
+
+  subject { build_stubbed(:model_with_timestamps) }
+
+  it "assigns the exact same datetime" do
+    expect(subject.created_at).to eq(subject.updated_at)
+  end
+end
+
 describe "a stubbed instance overriding strategy" do
   include FactoryBot::Syntax::Methods