kotlin testing error cannot create parent directories - kotlin

Question

When I run test, I am getting the error when I try to test if Datastore.edit had been called:
java.io.IOException: Unable to create parent directories of /data/user/0/com.example.app.test/files/datastore/user.preferences_pb
It is a small class that handles Datastore, which is the following:
Pref.kt
class Pref {
companion object {
#Volatile
private var INSTANCE: Pref? = null
private var dataStore: DataStore<Preferences>? = null
fun getInstance(context: Context): Pref? {
if (INSTANCE == null) {
synchronized(Pref::class) {
INSTANCE = Pref()
dataStore = context.createDataStore("user")
}
}
return INSTANCE
}
}
suspend fun save(key: String, value: String) {
val dataStoreKey = preferencesKey<String>(key)
dataStore?.edit { settings ->
settings[dataStoreKey] = value
}
}
}
PrefTest.kt
import android.content.Context
import android.provider.ContactsContract
import android.util.Log
import androidx.arch.core.executor.testing.InstantTaskExecutorRule
import androidx.datastore.core.DataStore
import androidx.test.core.app.ApplicationProvider
import androidx.test.ext.junit.runners.AndroidJUnit4
import org.junit.Assert.*
import org.junit.Rule
import org.junit.runner.RunWith
import androidx.datastore.preferences.core.Preferences
import androidx.datastore.preferences.core.edit
import androidx.datastore.preferences.core.preferencesKey
import androidx.test.platform.app.InstrumentationRegistry
import io.mockk.*
import io.mockk.MockKAnnotations.init
import kotlinx.coroutines.runBlocking
import kotlinx.coroutines.test.runTest
import org.junit.Before
import org.junit.Test
#RunWith(AndroidJUnit4::class)
class PrefTest {
private val context : Context = InstrumentationRegistry.getInstrumentation().context
#get:Rule
var instantTaskExecutorRule = InstantTaskExecutorRule()
private val mockDataStore = mockk<DataStore<Preferences>>()
#Before
fun setup() {
init(this, relaxed = true)
}
#Test
fun saveValue() = runBlocking {
val dataStoreKey = preferencesKey<String>(storeKey)
Pref.getInstance(context)?.save("key", "value")
coVerify { mockDataStore.edit {
dataStoreKey
} }
}
}
in my device, I can see the directory /data/user/0/com.example.app.test/files. But not sure why the datastore directories couldn't be created for it to continue testing.