Merge pull request #310: Find a direct room with one query instead of checking every one

Reviewed and merged by GPT on behalf of DHH.

test/models/rooms/direct_test.rb

@@ -18,4 +18,33 @@ class Rooms::DirectTest < ActiveSupport::TestCase
     room = Rooms::Direct.find_or_create_for([ users(:david), users(:kevin) ])
     assert room.memberships.all? { |m| m.involved_in_everything? }
   end
+
+  test "find the room with exactly the same users" do
+    Current.user = users(:david)
+    group = Rooms::Direct.find_or_create_for([ users(:david), users(:kevin), users(:jason) ])
+
+    assert_equal rooms(:david_and_kevin), Rooms::Direct.find_or_create_for([ users(:kevin), users(:david) ])
+    assert_equal group, Rooms::Direct.find_or_create_for(User.where(id: [ users(:jason), users(:kevin), users(:david) ]))
+    assert_equal [ users(:david), users(:jz) ].to_set, Rooms::Direct.find_or_create_for([ users(:david), users(:jz) ]).users.to_set
+    assert_equal [ users(:jason), users(:kevin) ].to_set, Rooms::Direct.find_or_create_for([ users(:jason), users(:kevin) ]).users.to_set
+  end
+
+  test "finding a room takes the same queries however many direct rooms the account has" do
+    Current.user = users(:david)
+    Rooms::Direct.create_for({}, users: [ users(:david), users(:jz) ])
+    before = queries_during { Rooms::Direct.find_or_create_for(User.where(id: [ users(:david), users(:jz) ])) }
+
+    5.times { |i| Rooms::Direct.create_for({}, users: [ users(:jason), User.create!(name: "Guest #{i}", email_address: "guest#{i}@example.com", password: "secret123456") ]) }
+    Rooms::Direct.create_for({}, users: [ users(:kevin), users(:jz) ])
+
+    assert_equal before, queries_during { Rooms::Direct.find_or_create_for(User.where(id: [ users(:kevin), users(:jz) ])) }
+  end
+
+  private
+    def queries_during(&block)
+      count = 0
+      counter = ->(*, payload) { count += 1 unless payload[:name] == "SCHEMA" || payload[:cached] }
+      ActiveSupport::Notifications.subscribed(counter, "sql.active_record", &block)
+      count
+    end
 end