Enables demo mode on a device for the purpose of taking screenshots

DemoModeEnabler.kt

class DemoModeEnabler {

    fun enable() {
        executeShellCommand("settings put global sysui_demo_allowed 1")
        sendCommand("exit")
        sendCommand("enter")
        sendCommand("notifications", "visible" to "false")
        sendCommand("network", "wifi" to "hide")
        sendCommand("battery", "level" to "100", "plugged" to "false")
        sendCommand("clock", "hhmm" to "1000")
    }

    fun disable() {
        sendCommand("exit")
    }

    private fun sendCommand(command: String, vararg extras: Pair<String, Any>) {
        val exec = StringBuilder("am broadcast -a com.android.systemui.demo -e command $command")
        for ((key, value) in extras) {
            exec.append(" -e $key $value")
        }
        executeShellCommand(exec.toString())
    }

    private fun executeShellCommand(command: String) {
        waitForCompletion(InstrumentationRegistry.getInstrumentation().uiAutomation.executeShellCommand(command))
    }

    private fun waitForCompletion(descriptor: ParcelFileDescriptor) {
        val reader = BufferedReader(InputStreamReader(ParcelFileDescriptor.AutoCloseInputStream(descriptor)))
        reader.use {
            it.readText()
        }
    }
}

DemoModeRule.kt

class DemoModeRule: TestRule {

    private val helper = DemoModeEnabler()

    override fun apply(base: Statement, description: Description): Statement {
        return DemoModeStatement(base)
    }

    private inner class DemoModeStatement(private val base: Statement) : Statement() {
        override fun evaluate() {
            helper.enable()
            base.evaluate()
            helper.disable()
        }
    }
}

Hi @hvisser, is it working for non rooted device?