Use initializer to configure tenant mode

test/models/account/multi_tenant_test.rb

@@ -0,0 +1,22 @@
+require "test_helper"
+
+class MultiTenantTest < ActiveSupport::TestCase
+  test "accepting_signups? is true when multi_tenant is enabled" do
+    with_multi_tenant_mode(true) do
+      assert Account.accepting_signups?
+    end
+  end
+
+  test "accepting_signups? is false when multi_tenant is disabled and accounts exist" do
+    with_multi_tenant_mode(false) do
+      assert_not Account.accepting_signups?
+    end
+  end
+
+  test "accepting_signups? is true when multi_tenant is disabled but no accounts exist" do
+    with_multi_tenant_mode(false) do
+      Account.delete_all
+      assert Account.accepting_signups?
+    end
+  end
+end