[android-studio] Android Studio: Module won't show up in "Edit Configuration"

I finally figure out why the module is not showed up when I add configuration for AndroidTests for a com.android.library module.

If you include your library module in your application's build.gradle like this:

compile project(':yourlibrary')

Since for library module it is compiled with release mode by default, you can't run Android Tests for it, that's why it won't show up in the module list. I fixed it with following modification:

Add following configuration to the build.gradle of your library module:

     publishNonDefault true

By make following changes, you can debug compile your library by editing the build.gradle of your application module like following:

-    compile project(':yourlibrary')
+    debugCompile project(path: ':yourlibrary', configuration: 'debug')
+    releaseCompile project(path: ':yourlibrary', configuration: 'release')

Then sync it and you'll find it shows in the list.