Mechanical Turk

Inspiration of the Mechanical Turk is drawn from the Mechanical Turk.

Build Status

Master

The Idea

In stead of pulling an input as a person to test the correctness of the ET Engine, we can let Rspec do that. We define what we expect from ETengine. E.g., when we expect a clean sheet scenario to have exactly 160 MegaTons of CO₂-emissions, we can write:

@scenario.new
@scenario.co2.value should be == 163_516_595_413.92465 #kg

Then we run the test (either from the command line using $> rspec specs/. or hitting CMD+R in TextMate)... and hopefully we get the soothing green light that everything is as expected:

Or when ETEngine returns something else then expected, we get a warning and some explanation:

Input and output

ETengine is an input-output system. With the Turk you can 'set' inputs to certain positions, and expect the outcome to not change, the change in a direction (up or down), or to increase with at least 5%, or to change somewhere between 4% and 6%.

Input: setting the 'sliders' of the model

We can set a input and change the expectation accordingly:

@scenario.number_of_energy_power_ultra_supercritical_coal = 3

We can also set a combination of inputs, e.g. that are in a group, or when we went to test a special combination that produces an error prone situation:

@scenario.households_space_heater_micro_chp_network_gas_share = 60 #percent
@scenario.households_heat_network_connection_steam_hot_water_share = 40 #percent
@scenario.number_of_energy_power_ultra_supercritical_coal = 10 #number of typical plants

Please note that the inputs are represented by sliders on etmodel, but as answers on the mixer

And then we can expect ETEngine to return specific numbers

We can define that the outcome of the scenario is an exact number:

@scenario.number_of_energy_power_ultra_supercritical_coal = 3
@scenario.co2.value should be == 163_516_595_413.0 #kg

But perhaps more useful is that we can specify that an outcode of the model (e.g. "Co2") increases with a certain value.

@scenario.co2.increase.should be == 1_000_000 #kg

When we do not care about the exact number, but we want the outcome to increase by at least a certain value, we write:

@scenario.co2.increase.should be > 1 #Mton

This can be very handy to test the direction of an outcome. E.g. we might want to specifiy that the outcome of a query should be positive or negative:

@scenario.co2.increase.should be > 0
@scenario.co2.increase.should be < 0

This can also be written shorter as:

@scenario.co2.should increase
@scenario.co2.should decrease

Attention: increase and decrease compare the number with the one before the slider was pulled and not the increase of future compared to present.

To test the de/increase of future in relation to the present:

@scenario.co2.future_increase.should > 0
@scenario.co2.future_decrease.should > 0

Of course, sometimes we want a number not to change when we pull a input:

@scenario.footprint.increase.should be == 0

or, shorter variant:

@scenario.footprint.should not_change

If we are not sure (or do not care) about the specific change we can draw up boundaries, like this:

@scenario.import.increase.should be > 0.03 #percent
@scenario.import.increase.should be < 0.05 #percent

Which can also be put on one line:

@scenario.import.should be_within(0.01).of(0.04)

We can run these specs for specific countries, end_years, and other options that are supported in the model

@scenario.new
  area_code: "ro"
  end_year: 2044
  use_fce: true
  merit_order: true

More on Rspec

Please check out the RSpec documentation on the possibilities and best practices of using RSpec.

Folder structure and file naming

All the tests belong in the directory /spec. Put tests that belong together into properly named subdirectories. Please be sure that you give your test file a easily understandable name. It has to end with _spec.rb.

Template for test

Please check out a few of the current tests in the spec directory for some example tests.

Your test at least has to contain the following:

require 'spec_helper'

describe "Your issue/challenge" do

  it "should do something that I expect" do
    scenario = Scenario.new(area_code: 'nl', end_year: 2050)
    scenario.a_slider_key
  end

end

Test different ETEngines

The Mechanical Turk by default tests the Beta ETEngine server, but you can test other servers by adding a config.yml file with your settings:

$> cp config.yml.sample config.yml
$> echo "server_addr: "http://etengine.dev" > config.yml
$> rspec spec

or, by passing an Environment Variable to rspec:

$> API=http://etengine.dev rspec spec

Limitations

The Mechanical Turk tests the outcome (i.e. the numbers) of ETEngine. Of course, the different interfaces (etflex, etmodel and energymixer) can still break!

How to run the tests

• Run bundle install in your local directory to make sure you have all dependencies installed
• Run all the specs using: rspec spec from the root directory of this repository on your local box
• Run the specs on TextMate using a Rspec plugin, e.g. the one from David Chelimsky
• Run the specs from Vim using a plugin