© 2019 Martin J. Dürst 青山学院大学

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• テスト終了後はマウス・キーボードに一切触らないこと

Today's Schedule

• Minitest
• Last week's exercises and homework
• Model generation
• Validation
• Testing
• Today's exercises

Last Lecture's Exercises

Ideal split between controller and view:

• Controller creates/calculates/prepares data (@time or @count)
• View takes care of display (repetitions, formatting)

Model Generation

• Last week, we generated a controller (SayController in app/controllers/say_controller.rb) with
  rails generate controller Say hello
(rails generate controller Controller action)
• Today, we will generate a model with e.g.
  rails generate model Wrestler name:string height:decimal ...
  (rails generate model Model field1:type1 field2:type2 ...)
• The types are generic types that work for ActiveRecord, Ruby, and various databases

Rails Datatypes

The main datatypes that can be used for model generation are as follows:

Validation

• Data in a database is used for a long time, and should be as correct as possible
• Some things are very difficult to check: names, exact values
• Many things can be checked automatically: presence of values, range of values
• Checking data validity is the job of the model
• Validations cannot be generated automatically, because there is not enough domain knowledge
  (Examples of domains: sumo, acting,...)
• In Rails, validations are very easy to write
• Validation instructions are added to the model class:

  class Wrestler < ApplicationRecord
    validates :name, presence: true
  end

Example Validations

(more at https://guides.rubyonrails.org/active_record_validations.html)

• Make sure the data is present: presence: true
• Make sure the data is numeric: numericality: true
• Make sure a number is integral: numericality: { only_integer: true }
• Allow absent (nil) data for numbers: numericality: { allow_nil: true }
• Check for value range: numericality: { greater_than: 50 }
• Check for a fixed set of values: inclusion: { in: ['序の口', '序二段', ...] }

Testing

• Testing programs is very important, for the following reasons:
  • Makes expectations clear
  • Helps catch misunderstandings
  • Helps catch future incompatible changes
• Many software companies employ more testers than programmers
• Writing tests while writing programs is very efficient

Testing in Rails

• Rails comes with a setup (environment) for testing
• Generators (rails generate ...) automatically create the necessary test files
• The actual tests have to be written by hand (because there is not enough domain knowledge)
• We will write tests for a model today

Rails Model Tests

(more at https://guides.rubyonrails.org/testing.html#model-testing and other parts of that Web page; see also documentation for Minitest)

• Model tests go into the file test/models/model_test.rb, e.g. test/models/wrestler_test.rb
• Tests are run with rails test; it is possible to run only model tests with rails test:models
• All tests are created by calling the method test in a class ModelTest (e.g. WrestlerTest), which is a subclass of ActiveSupport::TestCase
• The method test takes a description string and a block (do...end)
• The block contains one or more assertions
• Assertions can be assert, assert_equal, and many more
• The setup method can be used to create some data that can be reused in some or all of the tests (use instance variables to access the data in test methods)
• After checking for validity (assert hoge.(in)valid?), error details can be checked with
  assert hoge.errors[:real_name].any? or
  assert_equal ["must be greater than 50"], hoge.errors[:height]

Exercise 8a: Setting up the Actor Model

• Create a rails application named acting.
• Create a model named Actor with the following fields (in this order!):
  name, real_name (本名), birth_date, origin, height, weight, gender (male or female), blood_type (A/B/O/AB)
• The fields should have the following types:
  • name, real_name, origin, gender, and blood_type should be strings
  • height should be an integer
  • weight should be a decimal
  • birth_date should be a date
• Hint: There may be an error message regarding Clusivity. You can ignore it.
• Use rails db:migrate to generate the database
• Using your editor and SQLiteStudio, have a look at the following:
  • db/schema.rb
  • db/migrate/20190603HHMMSS_create_actors.rb
  • db/development.sqlite3 (in particular the Structure tab)
• Check that the order and type of the fields is correct
  (there will be three additional fields, id, created_at, and updated_at, which are generated and used automatically by Rails)
• If the order and types are not correct, delete the application and start again
• Submit the file schema.rb Moodle (deadline: 17:00).

Exercise 8b: Adding Validations

• Download the files actors_controller.rb, new.html.erb, and show.html.erb (you have to create a directory actors in app/view)
• Add the following line to config/routes.rb:
  resources :actors
• Start the server and direct a browser at http://localhost:3000/actors/new
• Add some data, including data that doesn't make sense (e.g. non-existent genders or blood types, out-of-range height, weight, or birth dates,...) or data where some fields are just missing.
• Check the data with SQLiteStudio (Data tab, Grid view, use the blue button in the upper left corner for updates)
• One-by-one, add the following validations to your model. For each validation, check that you get an appropriate error message. Also, check that the error message goes away when you fix the error.
  • Check presence for all fields except weight (some actors and actresses don't want to make their weight public)
  • Check for sensible lower and upper bounds for birth_date, height, and weight (if present)
  • Check for allowed values for gender and blood_type
• Submit the file app/models/actor.rb to Moodle (deadline: 18:00)
• Submit your model file before the deadline, with as many validations as possible

Exercise 8c: Adding Tests

• Run rails db:migrate RAILS_ENV=test to set up the test database
• Run rails test. You should get 0 runs, 0 asssertions, 0 failures, 0 errors, 0 skips.
• If there is a long error message relating to chromedriver-helper, do the following:
  • Remove the file Gemfile.lock
  • In Gemfile, comment out the lines relating to capybara, selenium-webdriver, and chromedriver-helper
  • Run bundle install
• One-by-one, in the file test/models/actor_test.rb, add tests for the following. Make sure that for each test, you check that it fails (when the corresponding validation is commented out) and that it succeeds (when the corresponding validation is not commented out). Try to use many calls to test, with only very few assertions per call.
  • Actor fields must not be empty (except weight; make sure you have a test for each field)
  • birth_date, height, and weight have to be inside the bounds defined in the validation
  • Error messages are equal to the messages that Rails actually sends
• Submit the file test/models/actor_test.rb to Moodle (deadline: 19:00)
• Submit your test file before the deadline, with as many tests/assertions as possible

Exercise 8d: Add Data to Database

• Make sure all the valitations are activated, and your tests work
• Using SQLiteStudio, delete all the data from the database (most of it is bogus, anyway)
• Using your application, add 5 real actors/actresses with correct data to the database
• You can get real data from Wikipedia or IMDB,...
• There will be a deduction if two or more students provide data for the same actor/actress
• Submit the database file (db/development.sqlite3) to Moodle (deadline Wednesday, 19:00)

Homework

• Study the files that were generated with rails generate model .... Try to get an idea about what each line in each file means. (you do not have to read documentation for this homework, but you may occasionally have to consult a dictionary)
• Think about Web applications that you might want to create (using Rails or any other technology). Write down your ideas.