Migrating Junit4 tests to androidx: What causes 'delegate runner could not be loaded'?

Question

I am migrating my app to androidx, I can\'t seem to get my unit tests working. I took example from Google\'s AndroidJunitRunnerSample, which has been updated to use the new

Answer 1

I fixed with this configuration:

My dependencies:

/*Instrumentation Test*/
androidTestImplementation "org.assertj:assertj-core:3.12.2"
androidTestImplementation ('androidx.test.espresso:espresso-core:3.2.0',{
    exclude group: 'com.android.support', module: 'support-annotations'
})
androidTestImplementation "androidx.arch.core:core-testing:2.1.0-rc01"

In my defaultConfig section I have:

defaultConfig {
    applicationId "uy.edu.ude.archcomponents"
    minSdkVersion 22
    targetSdkVersion 28
    versionCode 1
    versionName "1.0"
    testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"

    testInstrumentationRunnerArguments clearPackageData: 'true'
}

In the test I have:

package uy.edu.ude.archcomponents.repository

import androidx.arch.core.executor.testing.InstantTaskExecutorRule
import androidx.room.Room
import androidx.test.platform.app.InstrumentationRegistry
import androidx.test.runner.AndroidJUnit4
import com.example.android.roomwordssample.WordDao
import com.example.android.roomwordssample.WordRoomDatabase
import kotlinx.coroutines.runBlocking
import org.assertj.core.api.Assertions.assertThat
import org.junit.After
import org.junit.Before
import org.junit.Rule
import org.junit.Test
import org.junit.runner.RunWith
import uy.edu.ude.archcomponents.entity.Word
import java.io.IOException


@RunWith(AndroidJUnit4::class)
class WordDaoTest {

    @get:Rule
    val instantTaskExecutorRule = InstantTaskExecutorRule()

    private lateinit var wordDao: WordDao
    private lateinit var db: WordRoomDatabase

    @Before
    fun createDb() {
        val context = InstrumentationRegistry.getInstrumentation().context
        // Using an in-memory database because the information stored here disappears when the
        // process is killed.
        db = Room.inMemoryDatabaseBuilder(context, WordRoomDatabase::class.java)
                // Allowing main thread queries, just for testing.
                .allowMainThreadQueries()
                .build()
        wordDao = db.wordDao()
    }

    @After
    @Throws(IOException::class)
    fun closeDb() {
        db.close()
    }

    @Test
    @Throws(Exception::class)
    fun insertAndGetWord() {
        runBlocking {
            val word = Word("word")
            wordDao.insert(word)
            val allWords = wordDao.getAlphabetizedWords().waitForValue()
            assertThat(allWords[0].word).isEqualTo(word.word)
        }
    }
}

I also use the android plugin version 3.4.2. I took the config from here