Under IFRS, when do firms test plant assets and finite-life intangible assets for impairment?

Question:

Under IFRS, when do firms test plant assets and finite-life for impairment?
Intangible Assets
An intangible asset is a resource controlled by an entity without physical substance. Unlike other assets, an intangible asset has no physical existence and you cannot touch it.Types of Intangible Assets and ExamplesSome examples are patented...