Manifest and setup issues getting Robolectric working with Android Studio 1.1.0

I am trying to get Robolectric tests up and working in our current project, and not having a lot of luck. My preference would be to get these to run within Android Studio 1.1.0+. This is my project structure:

and here is my test:

import android.widget.Button;

import com.mycompany.android.app.R;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.robolectric.Robolectric;
import org.robolectric.RobolectricTestRunner;
import org.robolectric.annotation.Config;

import static org.junit.Assert.assertNotNull;

@Config(manifest = "AndroidManifest.xml")
@RunWith(RobolectricTestRunner.class)
public class SplashActivityTest {

    private SplashActivity splashActivity;

    @Before
    public void setup() {
        splashActivity = Robolectric.buildActivity(SplashActivity.class).create().start().resume().get();
    }

    @Test
    public void shouldNotBeNull() {
        Button signUpButton = (Button) splashActivity.findViewById(R.id.sign_up_button);
        assertNotNull(signUpButton);

        Button loginButton = (Button) splashActivity.findViewById(R.id.login_button);
        assertNotNull(loginButton);
    }

}

No matter what I do to try and get the framework to find the test by changing the path to the manifest, it cannot find it - either I get WARNING: No manifest file found at ./AndroidManifest.xml.Falling back to the Android OS resources only. messages, or API Level XX is not supported - Sorry! messages. In the end, I think this is the reason I'm getting the following errors when the test runs:

android.content.res.Resources$NotFoundException: unknown resource 2130903074

I do have the experimental option turned on, have the right Gradle plugin configured (unit tests work fine), but I'm not sure what I'm missing to get instrumentation tests up and running.

App-level build file:

apply plugin: 'org.robolectric'

testCompile 'junit:junit:4.12'
testCompile 'org.mockito:mockito-core:1.9.5'
testCompile 'org.robolectric:robolectric:2.4'
testCompile 'org.hamcrest:hamcrest-core:1.1'
testCompile 'org.hamcrest:hamcrest-library:1.1'
testCompile 'org.hamcrest:hamcrest-integration:1.1'

Top-level build file:

dependencies {
    classpath 'com.android.tools.build:gradle:1.1.0'
    classpath 'org.robolectric:robolectric-gradle-plugin:1.0.0'
}