Jetpack DataStore in MVVM

LocalRepository.kt

import com.github.crazygit.tikheart.TikHeartApplication
import com.github.crazygit.tikheart.data.dao.UserInfoDao
import com.github.crazygit.tikheart.data.model.UserInfo
import com.github.crazygit.tikheart.utilities.LocalStorage


object LocalRepository {
    private val localStorage = LocalStorage(TikHeartApplication.appContext)
    private val localUserDao = UserInfoDao(localStorage)

    fun getUserInfo() = localUserDao.getUserInfo()
    suspend fun saveUser(userInfo: UserInfo) = localUserDao.saveUserInfo(userInfo)
    suspend fun removeUserInfo() = localUserDao.removeUserInfo()
}

LocalStorage.kt

import android.content.Context
import androidx.datastore.core.DataStore
import androidx.datastore.preferences.core.Preferences
import androidx.datastore.preferences.core.edit
import androidx.datastore.preferences.core.preferencesKey
import androidx.datastore.preferences.createDataStore
import kotlinx.coroutines.flow.map

class LocalStorage(appContext: Context) {
    val dataStore: DataStore<Preferences> = appContext.createDataStore(
        name = "AppDataStore"
    )

    suspend inline fun <reified T> save(key: Preferences.Key<T>, value: Any) {
        dataStore.edit {
            it[key] = value as T
        }
    }

    inline fun <reified T> get(key: Preferences.Key<T>, default: T) = dataStore.data.map {
        it[key] ?: default
    }

    companion object PreferenceKeys {
        val USER_INFO_KEY = preferencesKey<String>("user_info")
    }
}

LocalStorageTest.kt

import android.content.Context
import androidx.test.ext.junit.runners.AndroidJUnit4
import androidx.test.platform.app.InstrumentationRegistry
import com.github.crazygit.tikheart.utilities.LocalStorage
import com.google.common.truth.Truth.assertThat
import kotlinx.coroutines.flow.first
import kotlinx.coroutines.runBlocking
import org.junit.Before
import org.junit.Test
import org.junit.runner.RunWith

@RunWith(AndroidJUnit4::class)
class LocalStorageTest {
    private val appContext: Context = InstrumentationRegistry.getInstrumentation().targetContext
    private lateinit var localStorage: LocalStorage

    @Before
    fun init() {
        localStorage = LocalStorage(appContext)
    }

    @Test
    fun testLocalStorage() = runBlocking {
        val data = "hello"
        localStorage.save(LocalStorage.USER_INFO_KEY, data)
        assertThat(localStorage.get(LocalStorage.USER_INFO_KEY, "").first()).isEqualTo(data)
    }
}

UserInfoDao.kt

import com.github.crazygit.tikheart.utilities.LocalStorage
import com.github.crazygit.tikheart.data.model.UserInfo
import com.google.gson.Gson
import com.google.gson.JsonSyntaxException
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.map

class UserInfoDao(private val localStorage: LocalStorage) {
    fun getUserInfo(): Flow<UserInfo?> = localStorage.get(LocalStorage.USER_INFO_KEY, "").map {
        try {
            Gson().fromJson(it, UserInfo::class.java)
        } catch (e: JsonSyntaxException) {
            null
        }
    }

    suspend fun saveUserInfo(userInfo: UserInfo) =
        localStorage.save(LocalStorage.USER_INFO_KEY, Gson().toJson(userInfo))

    suspend fun removeUserInfo() = localStorage.save(LocalStorage.USER_INFO_KEY, "")

}