Type Android Junit4 not present exception

Hopefully someone can give you a better answer as to why, but I had this exact same problem. I did the following:

• Build > Clean Project,
• Ran the app on the emulator

This done, I was able to get back into a state where I could run the tests again.

Writing steps if someone facing issue while edit configuration for above @Bohsen's answer

1. In Android Studio, click Run > Edit Configurations (or press alt + shift + f10 if on Windows) to open the configuration editor.
2. The left panel of the window shows configurations and their groups.
   • Android JUnit group
   • Android instrumented tests

If your test is an instrumentation test, delete it from any JUnit tests groups.

If your test is a JUnit test, delete it from any instrumentation test groups.

For example, my test (DBTest.kt) was appearing in both Android JUnit and Instrumented group's section. So I deleted from JUnit group and ran it again, it was working fine.

This is caused by Android Studio trying to execute an instrumentation test as a JUnit test.

I had to go to 'Edit Configurations...' and delete the configuration from Android JUnit group and manually add to the 'Android Instrumented Tests' group. After this I had no problem executing the tests.

In Android Studio, click Run > Edit Configurations.

https://developer.android.com/studio/run/rundebugconfig