NativeScript/tests/app/ui/bottom-navigation/bottom-navigation-tests-native.android.ts

import { BottomNavigation } from "tns-core-modules/ui/bottom-navigation";

export function getNativeTabCount(tabView: BottomNavigation): number {
    // there is no native tab content view implementation for Android Bottom Navigation
    return tabView.items.length;
}

export function selectNativeTab(tabView: BottomNavigation, index: number): void {
    const bottomNavigationBar = (<org.nativescript.widgets.BottomNavigationBar>(<any>tabView)._bottomNavigationBar);

    if (bottomNavigationBar) {
        bottomNavigationBar.setSelectedPosition(index);
    }
}

export function getNativeSelectedIndex(tabView: BottomNavigation): number {
    // there is no native tab content view implementation for Android Bottom Navigation
    return tabView.selectedIndex;
}

export function getNativeFont(tabView: BottomNavigation): any {
    const tv: android.widget.TextView = (<org.nativescript.widgets.BottomNavigationBar>(<any>tabView)._bottomNavigationBar).getTextViewForItemAt(0);
    if (tv) {
        return {
            typeface: tv.getTypeface(),
            size: tv.getTextSize()
        };
    }

    return null;
}

export function getOriginalFont(tabView: BottomNavigation): any {
    const tv: android.widget.TextView = (<org.nativescript.widgets.BottomNavigationBar>(<any>tabView)._bottomNavigationBar).getTextViewForItemAt(0);

    return {
        typeface: tv.getTypeface(),
        size: tv.getTextSize()
    };
}