Held: ,

Back to Outline 12 - Software as a Service. On to Outline 14 - Codes of Ethics.

Summary

We consider issues of behavior-driven design, using Cucumber as our BDD platform.

Related Pages

Overview

• TDD Basics.
• BDD Basics.
• Cucumber Basics.
• A Cucumber Example.
• Cucumber in Practice.

Administrivia

• Friday PSA.
  • https://prezi.com/dz6cu1yr83zn/what-does-consent-look-like/
  • http://www.theline.org.au/is-this-consent
  • https://www.youtube.com/playlist?list=PL3xP1jlf1jgJRkChwVOlwQcV0-UqcWiFV
• Cash for Dairy Barn
• I've heard from the SEPC that "CSC 321 feels like CSC 151 in that we're learning things that we'll never use."
  
  • I hope that you will learn a lot about software design in this course, and even if you don't use Rails again, the experience of thinking through the steps of building and installing sites will be useful.
  • Note that the ability to roll out an interactive site in a few hours is a great way to build a portfolio.
  • And CSC 151 is useful. As a recent alum said "151 teaches you most of the things you should know about Javascript."

Upcoming Work

• Saas HW 2 (Sinatra Hangman) for Monday. (It's in "Intro to BDD, TDD, and SaaS" on the MOOC.)
• Readings for Monday:
  • Don Gotterbarn, Keith Miller, and Simon Rogerson (October 1999). Computer Society and ACM approve Software Engineering Code of Ethics. IEEE Computer 32(10): 84-88. https://www.computer.org/cms/Computer.org/Publications/code-of-ethics.pdf
  • Peter G. Neumann (February 2015). Inside Risks: Far-sighted thinking about deleterious computer-related events. CACM 58 (2): 30-33. http://www.csl.sri.com/users/neumann/cacm235.pdf
  • ACM Council (October 1992). ACM Code of Ethics and Professional Behavior. http://www.acm.org/about/code-of-ethics/
• Reading Journal for Sunday night at 10pm. (Questions inspired by JLND.)
  • Subject: Reading Journal for Class 14 (Your Name)
  • What was the most familiar idea in today's readings on ethics? Where had you seen that idea before?
  • What surprised you the most in today's readings on ethics? Why was that idea surprising?
  • Are there ways in which agile practices help support ethical behavior or make it more difficult?
  • Any other reactions or points you would like to discuss?

Good Things to Do

See http://www.cs.grinnell.edu/~rebelsky/s2d@g/

• Jazz ensemble tonight at 7:30 in Herrick
• Faculty recital Saturday at 7:30 in Bucksbaum
• Film plus discussion Saturday at 4:00 in JRC 101.

Test-Driven Development

• What is it?
• How does it relate to the kinds of testing you've done in your other classes?
• Why do we do it?

Behavior-Driven Design

• What do you see as the key features of BDD?
• What differences do you see between BDD and TDD?
• What are some potential disadvatnages of BDD?

Cucumber Basics

• A programmatic approach to Behavior-Driven Design

• Often viewed in terms of a "testing stack"

  Features
  Scenarios
  Steps
  
  
  Step Definitions
  Support Code
  Automation Library
  

• Features, scenarios, and steps give the high-level limited-form natural-language definition of aspects of the user story.

• Step definitions indicate how to translate the steps to procedure calls. (Yay pattern matching!)
• Support code helps implement some of those calls.
• The automation library deals with common things, like fetching pages.
  • We often use Capybara to help with automation.

A Cucumber Example

Let's walk through some scenarios and think about what work we might have to do to implement these Cucumber scenarios. Do they affect model, view, or controller (or all three)? (Suppose we had the repaired version of the original database, with no director.)

Feature: search for movies by director

  As a movie buff
  So that I can find movies with my favorite director
  I want to include and search on director information in movies I enter

Background: movies in database

  Given the following movies exist:
  | title        | rating | director     | release_date |
  | Star Wars    | PG     | George Lucas |   1977-05-25 |
  | Blade Runner | PG     | Ridley Scott |   1982-06-25 |
  | Alien        | R      |              |   1979-05-25 |
  | THX-1138     | R      | George Lucas |   1971-03-11 |

Scenario: add director to existing movie
  When I go to the edit page for "Alien"
  And  I fill in "Director" with "Ridley Scott"
  And  I press "Update Movie Info"
  Then the director of "Alien" should be "Ridley Scott"

Scenario: find movie with same director
  Given I am on the details page for "Star Wars"
  When  I follow "Find Movies With Same Director"
  Then  I should be on the Similar Movies page for "Star Wars"
  And   I should see "THX-1138"
  But   I should not see "Blade Runner"

Scenario: can't find similar movies if we don't know director (sad path)
  Given I am on the details page for "Alien"
  Then  I should not see "Ridley Scott"
  When  I follow "Find Movies With Same Director"
  Then  I should be on the home page
  And   I should see "'Alien' has no director info"

Cucumber in Practice

• Our alums tell me that Cucumber has been less successful than people had expected.
• Ideal: Clients can write user stories.
  • Reality: Clients can read user stories.
  • Reality: Programmers have to write user stories.
• "Natural language" descriptions seem like a good idea, but managing three sets of files (use cases, patterns that translate to real test code, real test code) can be problematic.
• Automatic database setup is nice, but there are other Gems, such as FactoryGirl, that also help with database setup.
• I will not require you to write explicit Cucumber tests, but I will expect you to write use cases and to write tests (in RSpec or Minitest) that correspond to those use cases.