Referential spec: Add spec that two similar Referentials being persisted

Here we formalise a bug whereby two "identical" `Referential`s are able
to be saved even though Rails validation would normally prevent this. It
can happen when two `Referential`s are functionally identical (but have
different `slug`s, as this would trigger a Postgres error).

In practise, this happens when multiple imports of the same data are
launched at similar times.

We'll want to make this test pass by not allowing the identical
`Referential` to be created. This will be accomplished as agreed with
the team by a database table lock.

The threads and sleeps (in particular) are unfortunate necessities
needed to get the two `Referential`s to be saved at the same time.

TODO: Need to check this again with the threads & sleeps turned off to
confirm that this passes in that case (actually it doesn't), so this
test needs some modification in order to be correct.

Refs #5024

1 files changed, 36 insertions, 0 deletions

diff --git a/spec/models/referential_spec.rb b/spec/models/referential_spec.rb
index eed5467c1..d717511a1 100644
--- a/spec/models/referential_spec.rb
+++ b/spec/models/referential_spec.rb
@@ -126,4 +126,40 @@ describe Referential, :type => :model do
       end
     end
   end
+
+  # two referentials created at the same time should not be possible when both have the same data
+  context "when two identical Referentials are created at the same time" do
+    # TODO: Rename js: true to no transaction something
+    it "only creates one Referential", js: true do
+      begin
+        referential_1 = build(:referential)
+        referential_2 = referential_1.dup
+        referential_2.slug = "#{referential_1.slug}_different"
+
+        thread_1 = Thread.new do
+          ActiveRecord::Base.transaction do
+            referential_1.save
+            sleep 10
+          end
+        end
+
+        thread_2 = Thread.new do
+          sleep 5
+          ActiveRecord::Base.transaction do
+            referential_2.save
+          end
+        end
+
+        thread_1.join
+        thread_2.join
+
+        expect(referential_1).to be_persisted
+        expect(referential_2).not_to be_persisted
+
+      ensure
+        Apartment::Tenant.drop(referential_1.slug)
+        Apartment::Tenant.drop(referential_2.slug)
+      end
+    end
+  end
 end