tests/robotests/res/values/themes.xml

<resources>
    <style name="Theme.Settings" parent="@android:style/Theme.DeviceDefault.Settings">
        <!-- For AndroidX AlertDialogs -->
        <item name="alertDialogTheme">@style/Theme.AppCompat.DayNight.Dialog.Alert</item>
    </style>

    <!-- Override the main app's style for ActionPrimaryButton to get around lack of new style
         support in robolectric  -->
    <style name="ActionPrimaryButton" parent="android:Widget.DeviceDefault.Button"/>

    <!-- Test version of Theme.Settings.Home. Needed to build homepage activity in Robolectric -->
    <style name="Theme.Settings.Home" parent="Theme.AppCompat.DayNight.NoActionBar">
        <item name="colorPrimary">#ffffff</item>
        <item name="colorPrimaryDark">#ffffff</item>
        <item name="colorAccent">#ffffff</item>
        <item name="preferenceTheme">@style/SettingsPreferenceTheme</item>
        <item name="android:windowLightStatusBar">true</item>
        <!-- Define this color for material design -->
        <item name="colorPrimaryVariant">@android:color/white</item>
    </style>

</resources>