The items (dryer, washing machine, microwave and fridge-freezer) where bought after the tenants moved in.
So, they are not in tenancy and not planning to include them in the tenancy.
There are 3 tenants (not related) in a single tenancy and only one of them is moving out after the tenancy period is over. So, a new tenancy is created to remove the person who is moving out and include a new person.
The remaining tenants want to keep the items. So, not planning to remove them.
The items are only 1 year old.
The reason those items were gifted to them was to keep the tenants in the property.
They are 3 friends and wanted to rent somewhere and willing to pay good rent.
They did not want to buy white goods to avoid any confusion when they move out.
As Mr. T says, PAT testing is not legally required. It may be a condition of an HMO licence however, and I note that your property is an HMO. If your local authority has an Additional Licensing scheme covering 3 person HMOs then it may have a condition about PAT testing equipment. If you have paperwork that shows that the white goods belong to the tenants, then you would not be obliged to pay for this.