AccessTokenCreator.kt

package com.facebook

object AccessTokenCreator {
    fun createToken(grantedPermissions: Collection<String?>?): AccessToken? {
        return AccessToken("token", "appId", "userId", grantedPermissions,
                ArrayList<String>(), null, AccessTokenSource.WEB_VIEW, null, null, null)
    }
}

LoginClientCreator.kt

package com.facebook.login

import com.facebook.AccessTokenCreator.createToken
import com.facebook.login.LoginClient.Request
import com.facebook.login.LoginClient.Result

internal object LoginClientCreator {

    fun createRequest(): Request {
        val permissions: HashSet<String> = hashSetOf("user_actions.music", "user_friends", "user_likes", "email")
        return Request(LoginBehavior.NATIVE_WITH_FALLBACK, permissions, DefaultAudience.EVERYONE, "authType", "appId", "authId")
    }

    fun createResult(): Result? {
        val request: Request = createRequest()
        return Result(request, Result.Code.SUCCESS, createToken(request.permissions), null, null)
    }
}

LoginSignupActivityTest.kt

    @Test
    fun signupWithFacebook() {
        val resultData = Intent()
        resultData.putExtra("com.facebook.LoginFragment:Result", LoginClientCreator.createResult())
        intending(hasComponent(FacebookActivity::class.java.name))
                .respondWith(Instrumentation.ActivityResult(Activity.RESULT_OK, resultData))
        
        activityTestRule..launchActivity(Intent())

        // click signup fb button
        onView(withId(R.id.signup_with_facebook_button)).perform(click())

        // wait a bit while UI return the mock intent
        Thread.sleep(1000)

        // check UI is showing the user as logged in
        ...
    }