Opening Drawer From Espresso

Q: How to open the drawer from an instrumental test written with Espresso?

A:

First, you need a add espresso-contrib to your project. It has the needed DrawerActions class.

androidTestCompile 'com.android.support.test.espresso:espresso-contrib:2.2.2'

Then, you need to open the drawer with his openDrawer() method and the drawer layout ID. The generated one is R.id.material_drawer_layout

onView(withId(R.id.material_drawer_layout)).perform(DrawerActions.open());