Cannot resolve symbol InstantTaskExecutorRule

I open example code BasicRxJavaSample (from this article Room+RxJava) The main thing is there:

@Rule
public InstantTaskExecutorRule instantTaskExecutorRule = 
    new InstantTaskExecutorRule();

And BasicRxJavaSample is all ok. But I can not apply this in my test. That's what's going on:

Cannot resolve symbol InstantTaskExecutorRule

And manual import does not work:

My autocompletion works like this

But should be so

My app build.gradle (full gradle here):

// tests
testImplementation 'junit:junit:4.12'
androidTestCompile "com.android.support:support-annotations:$supportVersion"
testImplementation "android.arch.core:core-testing:$archVersion"
// Test helpers for Room
testImplementation "android.arch.persistence.room:testing:1.0.0"
// https://github.com/mockito/mockito
testImplementation 'org.mockito:mockito-core:2.13.0'
androidTestImplementation 'org.mockito:mockito-android:2.13.0'
// AndroidJUnitRunner and JUnit Rules
androidTestImplementation 'com.android.support.test:rules:1.0.1'
androidTestImplementation 'com.android.support.test:runner:1.0.1'
// https://developer.android.com/topic/libraries/testing-support-library/packages.html
androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
androidTestCompile 'com.android.support.test.espresso:espresso-idling-resource:3.0.1'

Replace testImplementation by androidTestImplementation. So the tests on folder androidTest can have access to the library.

dependencies {
    androidTestImplementation "androidx.arch.core:core-testing:2.1.0"
}

If you are not using androidx then use android.arch.core:core-testing:1.1.1

I know it's late but I would like to add one thing to this accepted answer.

If you want to use,

@Rule
public InstantTaskExecutorRule instantTaskExecutorRule = 
new InstantTaskExecutorRule();

in your JUnit test case, i.e., in test folder then use following dependency, i.e, with testImplementation

dependencies {
testImplementation "android.arch.core:core-testing:1.0.0"
}

If you want to use InstantTaskExecutorRule for your UI or integration test cases(androidTest folder), use androidTestImplementation. that is:

androidTestImplementation "android.arch.core:core-testing:1.0.0"

And if you want to add for both, use androidTestImplementation & testImplementation that is:

androidTestImplementation "android.arch.core:core-testing:1.0.0"

testImplementation "android.arch.core:core-testing:1.0.0"

For Android-X use below dependency:

androidTestImplementation 'androidx.arch.core:core-testing:2.0.0'

OR

testImplementation 'androidx.arch.core:core-testing:2.0.0'

for androidX migration, add

androidTestImplementation "androidx.arch.core:core-testing:2.0.0"

Please put this two dependencies in your gradle file,

dependencies {

    // Test helpers for LiveData
    testImplementation "android.arch.core:core-testing:1.0.0"

    // Test helpers for Room
    testImplementation "android.arch.persistence.room:testing:1.0.0"
}

Further information please go through this link, Android Architecture components integration guide

dependencies {
    testImplementation "androidx.arch.core:core-testing:2.1.0"
}