Test Error - NoClassDefFoundError: Failed resolution of: Lorg/hamcrest/Matchers

Issue

I am using Espresso for Instrumented Test but got this error on the Stack Trace.

The error being caused by a missing class as shown below:

Caused by: java.lang.ClassNotFoundException: Didn't find class "org.hamcrest.Matchers" on path: DexPathList[[zip file "/system/framework/android.test.runner.jar", zip file "/system/framework/android.test.mock.jar", zip file "/system/framework/android.test.base.jar", zip file "/data/app/~~vnZzxGNKnS4V6YkEf4falA==/com.example.android.architecture.blueprints.reactive.test-K_x0_yJ0hJeDHaJkDmHXRw==/base.apk", zip file "/data/app/~~oeYx2MgTcILbk-vq_WPx1A==/com.example.android.architecture.blueprints.reactive-0wMHYEe95hx_1cnbdAoZAw==/base.apk"],nativeLibraryDirectories

It first occurred immediately after I added this code in the Fragment Test:

These are my relevant Libs on the Gradle

I have these imports

import androidx.fragment.app.testing.launchFragmentInContainer
import androidx.test.espresso.Espresso.onView
import androidx.test.espresso.assertion.ViewAssertions.matches
import androidx.test.espresso.matcher.ViewMatchers.*
import androidx.test.ext.junit.runners.AndroidJUnit4
import org.hamcrest.core.IsNot.not

I have been stuck for the the last 2 hours and cannot find a solution. Plz help.

Solution

After struggling for a while I realized the error is being caused by espresso-contib and espresso-accessibility dependencies. My espresso version was the latest version 3.4.0-alpha05.

I removed them and tests passed.

Before including espresso-contrib & espresso-accessibility

/*core contains matches and view assertions, included by default on android project*/
androidTestImplementation "androidx.test.espresso:espresso-core:$espressoVersion"

//testing code for advanced views such as recyclerview and Date picker
androidTestImplementation "androidx.test.espresso:espresso-contrib:$espressoVersion"
androidTestImplementation "androidx.test.espresso:espresso-accessibility:$espressoVersion"
androidTestImplementation "androidx.test.espresso:espresso-intents:$espressoVersion"
androidTestImplementation "androidx.test.espresso.idling:idling-concurrent:$espressoVersion"

After comment out on both espresso-contrib & espresso-accessibility

//core contains matches and view assertions, included by default on android project
androidTestImplementation "androidx.test.espresso:espresso-core:$espressoVersion"
//testing code for advanced views such as recyclerview and Date picker
//androidTestImplementation "androidx.test.espresso:espresso-contrib:$espressoVersion"
//androidTestImplementation "androidx.test.espresso:espresso-accessibility:$espressoVersion"
androidTestImplementation "androidx.test.espresso:espresso-intents:$espressoVersion"
androidTestImplementation "androidx.test.espresso.idling:idling-concurrent:$espressoVersion"

Happy Coding Guys.

Answered By - Tonnie