[Proposal] Support Library for mocking SQLDelight queries

[Nillerr]

SQLDeligth is commonly used in Kotlin Multiplatform projects for state management. The generated queries can trivially be stubbed with Mockative given a few additional tools, which could be provided by a support library for mocking SQLDelight queries using Mockative, or as a non-mockative extension library. In particular, adding code like the following two classes will enable stubbing of SQLDelight generated queries using Mockative:

class IteratorCursor<RowType : Any>(private val results: Iterator<RowType>) : SqlCursor {
    // Could also use AtomicRef from `kotlinx.atomicfu`
    private var _current: RowType? by AtomicReference(null)
    
    // Could also use `by atomic()` from `kotlinx.atomicfu`
    private var isClosed: Boolean by atomic(false)

    val current: RowType?
        get() = _current

    override fun close() {
        isClosed = true
    }

    override fun getBytes(index: Int) = throw IllegalStateException()
    override fun getDouble(index: Int) = throw IllegalStateException()
    override fun getLong(index: Int) = throw IllegalStateException()
    override fun getString(index: Int) = throw IllegalStateException()

    override fun next(): Boolean {
        if (isClosed) {
            throw IllegalStateException("The cursor is closed")
        }
        
        if (results.hasNext()) {
            _current = results.next()
            return true
        }

        return false
    }

}

class IterableQuery<RowType : Any>(private val results: Iterable<RowType>) : Query<RowType>(
    queries = mutableListOf(),
    mapper = { cursor -> @Suppress("UNCHECKED_CAST") (cursor as IteratorCursor<RowType>).current!! }
) {
    override fun execute() = IteratorCursor(results.iterator())
}

Having these pieces you could write test stub code like the following:

given(queries).invocation { getOfflineRatesByBase(currencyResponse.base) }
  .thenReturn(IterableQuery(listOf(offlineRates)))

[abueide]

if anyone wanted to work on this i'd chip in $25