Mock exposed model's `select` results

We are using exposed 0.8.5. We are writing junits for our method which is as follows.

` override fun findById(id: Int): ModelObject? =
ExposedModel
.select { ExposedModel.id.eq(id) }
.map { it.asModelObject() }
.firstOrNull()`
We have mocked `ExposedModel.select`. But what should we in return values??
We need to test the map function here.