Test for issue https://github.com/dropbox/Store/issues/124

StoreTest.kt

package me.aartikov.storesample

import com.dropbox.android.external.store4.*
import kotlinx.coroutines.delay
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.toList
import kotlinx.coroutines.launch
import kotlinx.coroutines.runBlocking
import org.junit.Assert.assertEquals
import org.junit.Test

class StoreTest {

    @Test
    fun refreshWithError() = runBlocking {
        val fetcher = Fetcher.ofResult<Unit, String> {
            FetcherResult.Error.Message("Error")
        }
        val sourceOfTruth = InMemorySourceOfTruth()
        val store = StoreBuilder.from(fetcher, sourceOfTruth).build()

        val result = mutableListOf<StoreResponse<String>>()
        val job = launch {
            store.stream(StoreRequest.cached(Unit, refresh = true))
                .toList(result)
        }

        delay(1000)
        runCatching {
            store.fresh(Unit)
        }

        delay(1000)
        job.cancel()

        val expected = listOf<StoreResponse<String>>(
            StoreResponse.Loading(origin = ResponseOrigin.Fetcher),
            StoreResponse.Error.Message(message = "Error", origin = ResponseOrigin.Fetcher),
            StoreResponse.Error.Message(message = "Error", origin = ResponseOrigin.Fetcher)
        )
        assertEquals(expected, result)
    }
}

class InMemorySourceOfTruth : SourceOfTruth<Unit, String, String> {
    private val stateFlow = MutableStateFlow<String?>(null)

    override suspend fun delete(key: Unit) {
        stateFlow.value = null
    }

    override suspend fun deleteAll() {
        stateFlow.value = null
    }

    override fun reader(key: Unit): Flow<String?> {
        return stateFlow
    }

    override suspend fun write(key: Unit, value: String) {
        stateFlow.value = value
    }
}