This document discusses validation and unit testing in Ruby on Rails. It provides examples of: 1. Validating that text fields are not empty, price is greater than $0.01, title is unique, and image URL format is valid on the Product model. 2. Running model unit tests to validate the product attributes and specific validations like price being positive. 3. Using test fixtures to populate the test database with sample data and test assumptions by ensuring tests fail when validations are removed.

1. Validation and Unit Testing

2. Validations
• Title should not be empty
• Description should not be empty
• Price should be valid
• Models hook the code up to what’s in the db
• Everything that is put into / read from the db
goes through the model

3. Verify text fields have content
• app/models/product.rb
• validates :title, :description, :image_url,
:presense => true
• rails c
– p = Product.new
– p.valid? #=> false
– p.errors

4. Validate price > $0.00
• app/models/product.rb
• validates :price, :numericality =>
{:greater_than_or_equal_to => 0.01}
• p = Product.new({:title => "blah", :description
=> "blah", :image_url => "blah"})
• p.valid?
• p.errors

5. Validate uniqueness of title
• app/model/product.rb
• validates :title, :uniqueness => true
• p = = Product.new({:title => "blah", :description
=> "blah", :image_url => "blah", :price => "33"})
• p.save
• q = Product.new({:title => "blah", :description =>
"blah", :image_url => "blah", :price => "33"})
• q.valid # => false
• q.errors

6. Validates :image_url
• validates :image_url, :format => {
:with => %r{.(gif|jpg|png)$}i,
:message => ‘must be a URL for GIF, JPG or PNG
image’
}
• q = Product.new({:title => "blah", :description =>
"blah", :image_url => "blah", :price => "33"})
• q.valid?
• q.errors

7. What we’ve accomplished
• Product model verifies:
– field’s title, description and image URL are not
empty
– Price is a valid number > $0.01
– Title is unique
– Image URL looks reasonable
• http://localhost:3000/products

8. rake test
• 7 tests, 9 assertions, 2 failures, 0 errors, 0
skips
• Why are our tests failing?
• We added requirements for “valid” products

9. Update functional tests
• test/functional/products_controller_test.rb
@update = {
:title => 'Lorem Ipsum',
:description => 'Wibbles are fun',
:image_url => 'lorem.jpg',
:price => 19.95
}

10. Model Unit Tests
• test/unit/product_test.rb
test "product attributes must not be empty" do
product = Product.new
assert product.invalid?
assert product.errors[:title].any?
assert product.errors[:description].any?
assert product.errors[:price].any?
assert product.errors[:image_url].any?
end

11. rake test:units
• Runs only unit tests (not the full test suite)
• All unit tests pass!

12. Test more validations
test "product price must be positive" do
product = Product.new(:title => "My Book", :description => 'yyy', :image_url =>
'zzz.jpg')
product.price = -1
assert product.invalid?
assert_equal "must be greater than or equal to 0.01",
product.errors[:price].join(': ')
product.price = 0
assert product.invalid?
assert_equal "must be greater than or equal to 0.01",
product.errors[:price].join(': ')
product.price = 1
assert product.valid?
end

13. Test your assumptions
• These tests pass now
• Do your tests fail if you remove the
validation(s)?

14. Good/Bad Image_url’s
test "image url" do
ok = %w{ fred.gif fred.jpg fred.png FRED.JPG FRED.Jpg
http://a.b.c/x/y/z/fred.gif }
bad = %w{ fred.doc fred.gif/more fred.gif.more }
ok.each do |name|
assert new_product(name).valid?, "#{name} shouldn't be invalid"
end
bad.each do |name|
assert new_product(name).invalid?, "#{name} shouldn't be valid"
end
end

15. Test Fixtures
• Fills our test database with known sample
data
• Usually stored in CSV or YAML format (YAML is
more common)
• Fixture name must match the table you’re
testing
• YAML requires spaces not tabs, tabs produce a
syntax error

16. Products Fixture
• test/fixtures/products.yml
ruby:
title: Programming Ruby 1.9
description:
Book on programming Ruby. Commonly called
the "pick-axe" book.
price: 49.50
image_url: ruby.png

17. Using Fixture Data
• test/unit/product_test.rb
test "product is not valid without a unique title" do
product = Product.new(:title => products(:ruby).title,
:description => "yyy",
:price => 1,
:image_url => "fred.gif")
assert !product.save
assert_equal "has already been taken",
product.errors[:title].join('; ')
end

18. Commit your work
• git status
• git commit –a –m ‘Validation!’

19. Homework
• Add a validation that verifies the title is at least
10 characters long
– Checkout the :length argument to validate
• Add a validation that verifies the description is no
more than 50 characters long
• Change the error message on one or more of
your validations
• Pretend we operate a dollar store. Write a
validation that makes sure the price is between
$0.01 and $1.00.

20. Upgrade to Rails 3.0.3
• vi Gemfile
• bundle install
• rake test