I am not sure if you can run tests without source code. However you can manually test the apk with the use ofmand will need access to adb for that. If you have put adb on environment Path you can directly enter the belowmand - adb install
Where is the .APK on my Android studio project?
For finding the .apk file of your project . You first need to build your project with from Android Studio . You can build your project Build Generate Signed APK ( You need to give keystore to genearte signed apk) Or Build Build APK.( No keystore needed) After finishing Now see the notification of Right Bottom Corner in Android Studio. You can open files by clicking on notification or you can go to manually. Now Go to your project folder