Testing navigation bar buttons in RubyMotion

README.md

This is in answer to a question than came up in a course I am teaching. There do not appear to be any good examples of testing navigation bar button items, so I ran up this quick example. Two things of note:

1. You need to explicitly call your controller's "on_load" or similar method that actually adds the UI items, in your before block if you actually want to test those items. In the case of the default Red Potion app, we create the nav bar buttons in HomeScreen.on_load, so we need to call that method in the before block of our spec, to ensure the nav buttons are present.

2. The navigation bar is accessed from your UIViewController as navigationItem, and it is a UINavigationItem. You should check out the docs for these classes.

https://developer.apple.com/documentation/uikit/uiviewcontroller?language=objc https://developer.apple.com/documentation/uikit/uinavigationitem?language=objc

home_screen.rb

class HomeScreen < PM::Screen
  title "Your title here"
  stylesheet HomeScreenStylesheet

  def on_load
    set_nav_bar_button :left, system_item: :camera, action: :nav_left_button
    set_nav_bar_button :right, title: "Right", action: :nav_right_button

    @hello_world = append!(UILabel, :hello_world)
  end

  def nav_left_button
    mp 'Left button'
  end

  def nav_right_button
    mp 'Right button'
  end

  # You don't have to reapply styles to all UIViews, if you want to optimize, another way to do it
  # is tag the views you need to restyle in your stylesheet, then only reapply the tagged views, like so:
  #   def logo(st)
  #     st.frame = {t: 10, w: 200, h: 96}
  #     st.centered = :horizontal
  #     st.image = image.resource('logo')
  #     st.tag(:reapply_style)
  #   end
  #
  # Then in will_animate_rotate
  #   find(:reapply_style).reapply_styles#

  # Remove the following if you're only using portrait
  def will_animate_rotate(orientation, duration)
    find.all.reapply_styles
  end
end

home_screen_spec.rb

describe "HomeScreen" do
  tests HomeScreen

  before do
    @controller = HomeScreen.new
    @controller.on_load
  end

  it "should include the text label we added" do
    view('Hello World').should.not.be.nil
  end

  it "should have right nav bar item" do
    @controller.navigationItem.rightBarButtonItem.should.not.be.nil
  end
  it "should have left nav bar item" do
    @controller.navigationItem.leftBarButtonItem.should.not.be.nil
  end
  it "should not have back nav bar item" do
    @controller.navigationItem.backBarButtonItem.should.be.nil
  end
end