Class not found in roboeclectic with Android studio

I'm very new to Roboelectric. I've configured the roboelectric with one of my project, It always gives be the following exception.

Class not found: "com.customer.app.controllers.login.LoginControllerTest"
Process finished with exit code 1

I've included following lines in app/build.gradle

dependencies {

    testCompile 'junit:junit:4.12'
    testCompile 'org.hamcrest:hamcrest-core:1.3'
    testCompile "org.robolectric:robolectric:3.0"
    testCompile 'org.mockito:mockito-core:1.9.5'
}

My Project hierarchy is as follows :

 app -> src -> main -> java -> com.customer.app.controllers.login
LoginController.java

   app -> src -> test ->java -> com.customer.app.controllers.login.LoginControllerTest.java

Please help me out in resolving the issue. Thanks in advance!!!