Build local unit tests (No instrumentation registered! Must run under a registering instrumentation)

Question

Take a look at the official documentation. The section Include framework dependencies gives an example of how to set up a local unit testing to work with the environment android sdk. But if you do everything as in the example, the test does not start. I get an error instead

java.lang.IllegalStateException: No instrumentation registered! Must run under a registering instrumentation.

All attempts were made on a new project. Android Studio 3.3, gradle-4.10.1, build:gradle:3.3.0, Kotlin, and include Androidx artifacts.

Then added the following lines to the project with the specified configuration:

build.gradle

android {
    // ...
    testOptions {
        unitTests.includeAndroidResources = true
    }
}

dependencies {
    // ...
    // Already exist
    testImplementation 'junit:junit:4.12'
    // Added this line
    testImplementation 'androidx.test:core:1.0.0'
}

And the test body itself:

package com.example.myapplication

import android.content.Context
import androidx.test.core.app.ApplicationProvider
import org.junit.Test

class ExampleUnitTest {

    val context = ApplicationProvider.getApplicationContext<Context>()

    @Test
    fun readStringFromContext_LocalizedString() {
        System.out.println(context.applicationInfo.packageName)
    }
}

What am I doing wrong?

---

apply plugin: 'com.android.application'

apply plugin: 'kotlin-android'

apply plugin: 'kotlin-android-extensions'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.example.myapplication"
        minSdkVersion 15
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    testOptions {
        unitTests.includeAndroidResources = true
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'androidx.appcompat:appcompat:1.0.0-beta01'
    implementation 'androidx.core:core-ktx:1.1.0-alpha03'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.2'
    testImplementation 'junit:junit:4.12'
    testImplementation 'androidx.test:core:1.0.0'
    androidTestImplementation 'androidx.test:runner:1.1.0-alpha4'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.0-alpha4'
}

Answer 1

Update:

You should no longer encounter this error if you're using the latest gradle version.

---

I guess you need to include Robolectric dependency in your build.gradle and also specify test runner for your test:

@RunWith(RobolectricTestRunner.class)
class ExampleUnitTest {

After that it worked for me. I don't know why this info is not included in the Android documentation.