android - java.lang.RuntimeException: Delegate runner androidx.test.internal.runner.junit4.AndroidJUnit4ClassRunner for AndroidJUnit4 could not be found

Question

I am new to android testing and I don′t know how to solve this problem. Trying to run the following test file from my project:

@RunWith(AndroidJUnit4::class)
class AppDatabaseTest {
  private lateinit var userDAO: UserDAO // custom DAO interface
  private lateinit var db: AppDatabase

  @Before
  fun createDb() {
    db = Room.inMemoryDatabaseBuilder(
      ApplicationProvider.getApplicationContext(),
      AppDatabase::class.java
    ).allowMainThreadQueries().build()

    userDAO = db.userDAO()
  }

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

  @Test
  @Throws(Exception::class)
  fun insertAndReadUser() {
    val user = User(
      1,
      "123",
      "Test Name",
      "link.to/name/image#from_the.web"
    )
    userDAO.insert(user)

    val inserted = userDAO.getByUID(1)
    assertThat(inserted).isNotNull()
  }
}

Throws the following error on the run log:

java.lang.RuntimeException: Delegate runner androidx.test.internal.runner.junit4.AndroidJUnit4ClassRunner for AndroidJUnit4 could not be found.

Caused by: java.lang.ClassNotFoundException: androidx.test.internal.runner.junit4.AndroidJUnit4ClassRunner

Here are the project dependencies:

dependencies {
    def room_version = "2.2.6"

    implementation "androidx.room:room-runtime:$room_version"
    kapt "androidx.room:room-compiler:$room_version"
    implementation "androidx.room:room-ktx:$room_version"

    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
    implementation 'androidx.core:core-ktx:1.3.2'
    implementation 'androidx.appcompat:appcompat:1.2.0'
    implementation 'com.google.android.material:material:1.2.1'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
    implementation 'androidx.navigation:navigation-fragment-ktx:2.3.2'
    implementation 'androidx.navigation:navigation-ui-ktx:2.3.2'
    implementation 'androidx.lifecycle:lifecycle-livedata-ktx:2.2.0'
    implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.2.0'
    implementation 'androidx.navigation:navigation-fragment-ktx:2.3.2'
    implementation 'androidx.navigation:navigation-ui-ktx:2.3.2'

    testImplementation 'com.google.truth:truth:1.1'
    testImplementation 'junit:junit:4.13.1'
    testImplementation 'androidx.test.ext:junit:1.1.2'

    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
}

What could be causing this error and how to fix it?

Android Studio 4.1.1

Answer 1

I managed to find the issue. In fact, I had put the testing file on the wrong folder, the [test] folder instead of [androidTest] folder. Moving the file to the correct folder managed to solve the issue.