bring back that test and make it pass

bullet_train/app/models/concerns/users/base.rb

@@ -153,7 +153,7 @@ def developer?
   end
 
   def set_teams_time_zone
-    teams.where(time_zone: nil).each do |team|
+    teams.where(time_zone: [nil, "UTC"]).each do |team|
       team.update(time_zone: time_zone) if team.users.count == 1
     end
   end

bullet_train/test/models/team_test.rb

@@ -29,4 +29,34 @@ class TeamTest < ActiveSupport::TestCase
     team.reload
     assert_equal "UTC", team.time_zone
   end
+
+  test "default UTC time_zone is overwritten once the first user sets a time zone" do
+    team = Team.create!(name: "new test team")
+    user = User.create!(email: "[email protected]", password: "password", password_confirmation: "password", time_zone: nil)
+    Membership.create!(team: team, user: user)
+    team.reload
+    assert_equal "UTC", team.time_zone
+
+    user.time_zone = "Central Time (US & Canada)"
+    user.save
+
+    team.reload
+    assert_equal "Central Time (US & Canada)", team.time_zone
+  end
+
+  test "nil time_zone is overwritten once the first user sets a time zone" do
+    team = Team.create!(name: "new test team", time_zone: nil)
+    user = User.create!(email: "[email protected]", password: "password", password_confirmation: "password", time_zone: nil)
+    Membership.create!(team: team, user: user)
+    team.time_zone = nil
+    team.save
+    team.reload
+    assert_equal nil, team.time_zone
+
+    user.time_zone = "Central Time (US & Canada)"
+    user.save
+
+    team.reload
+    assert_equal "Central Time (US & Canada)", team.time_zone
+  end
 end