Test Run Failed: Instrumentation Run Failed Due To 'java.lang.ClassNotFoundException'

This is my first time setting up an Android test project to test a Android project. I've created a very basic test case which I'm trying to get to run, however what I have does no

Solution 1:

I had upgraded to androidx libraries and started getting this error.

To fix it, in build.gradle I changed the line:

testInstrumentationRunner 'android.support.test.runner.AndroidJUnitRunner'

to

testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"

Solution 2:

FYI I ran into this and had to add

<uses-library android:name="android.test.runner"/>

within my <application/> tag

Solution 3:

In my case, I was trying to run the tests on Jelly Bean emulator. Android instrumentation does not seem to support Jelly Bean. I could run the tests on lollipop.

You may also not able to run android tests through release build type. Ensure that debug build type is active.

Solution 4:

Figured out my issue and am posting the answer for documentation purposes...

The root of my problem was 2 different things:

1. I did some refactoring, which change the location of my android.app.Application class and my activities. This made it so my main program was not working as I needed to update my manifest in my android project.
2. After making the updates to my manifest in my android project, I had to make some updates in my android test project to point to the updated location of the class that extends android.app.Application.

After that, did some cleans and tested again and things were good.

Solution 5:

I got the same error because I forgot to add androidx.test:runner test dependency.

androidTestImplementation "androidx.test:runner:1.2.0"