Making assertions about a timeline of events more confident

[Anthony Green]

I'd like to apply some of the ideas I'm picking up from Confident Ruby to a test helper class I have to devise.

I have a timeline of events that originates in the browser via a JavaScript logger and arrives in ruby land as an array of hashes.

[ {type: "initialized"}, {type: "loadedPlaylist", url: "example.org/playlist"}, { type: 'playing' }, { type: 'paused' } ]

I would then like to make assertions on the behaviour of AUT based on the contents of the timeline

player.should have_loaded playlist

I've been using chained enumerators to find if an event exists and has the correct properties

timeline.select { |event| event[:type] == 'playlistLoaded' }.select { |event| event[:url] ==url }

but I have this feeling that there's probably a more confident approach

[Anthony Green]

After a bit of thinking I've got this implementation:

class TimelineOfEvents

  

  attr_reader :events

  

  class Event < Struct

    

    def == other

      self.class == Object.const_get(String(other).capitalize)

    end

  end

  

  def initialize events

    @events = events.collect { |event| Event(event) }

  end

  

  def Event obj

    obj = obj.dup.downcase_keys!.symbolize_keys!

    klass_name = obj.delete(:type).capitalize

    if Object.const_defined?(klass_name)

      Object.const_get(klass_name).new(*obj.values)

    else

      klass = Object.const_set(klass_name, Event.new(*obj.keys))

      klass.new(*obj.values)

    end

  end

end

timeline = TimelineOfEvents.new([{ 'type' => 'playing', 'url' => 'example.org' }])

timeline.events.first == Playing

[Eugene Kalenkovich]

I am not sure that your code became any more confident by moving of comparison of strings to comparison of classes.

You are also opening a security hole here - ajax events should be considered user input), so your approach requires additional level of input checking

Sorry that I am not giving any suggestions for different approaches - for this you'd have to describe your problem more precisely, At this moment your event and code examples are not consistent nor comprehensive enough to understand the problem

[Anthony Green]

On Friday, 22 November 2013 16:46:10 UTC, Eugene Kalenkovich wrote:

I am not sure that your code became any more confident by moving of comparison of strings to comparison of classes.

Not as end point no, but I was seeing whether this direction would permit me to add more useful semantics in the next iteration.

[Avdi Grimm]

On Thu, Nov 21, 2013 at 6:11 AM, Anthony Green <anthony.ch...@gmail.com> wrote:

timeline.select { |event| event[:type] == 'playlistLoaded' }.select { |event| event[:url] ==url }

I kinda like chained selects...

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Avdi Grimm
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