Testing with RSpec (RubyDay 2011)

Simone Carletti
[email protected]
twitter: @weppos
Testing with RSpec
2011
Monday, June 20, 2011

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Me.about(:robodomain)

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Me.about(:ifad)

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describe RSpec, "Agenda"

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Testing

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TDD seems to be applicable in various domains and can
signiﬁcantly reduce the defect density of developed
software without signiﬁcant productivity reduction of the
development team.
http://www.infoq.com/news/2009/03/TDD-Improves-
Quality

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The pre-release defect density of the four products,
measured as defects per thousand lines of code,
decreased between 40% and 90% relative to the
projects that did not use TDD. The teams' management
reported subjectively a 15–35% increase in initial
development time for the teams using TDD, though the
teams agreed that this was offset by reduced
maintenance costs.

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$ rspec
http://relishapp.com/rspec
https://github.com/rspec

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describe RSpec, "Features"

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Readability
describe Whois::Client do
describe "#initialize" do
it "accepts a timeout setting with a value in seconds" do
klass.new(:timeout => 100).timeout.should == 100
end
it "accepts a timeout setting with a nil value" do
klass.new(:timeout => nil).timeout.should be_nil
end
end
describe "#query" do
it "detects email" do
expect {
klass.new.query("[email protected]")
}.to raise_error(Whois::ServerNotSupported)
end
end
end

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Isolation
describe UsersController do
context "when logged as administrator" do
before(:each) do
log_in_as @admin = Factory(:user, :username => "admin")
end
context "with a bunch of users" do
before(:each) { @users = 3.times.map { Factory(:user) } }
describe "GET index"
end
context "with no users" do
describe "GET new"
describe "POST create"
end
describe "with a user" do
before(:each) { @user = Factory(:user) }
describe "GET show"
end
end
end

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Extensible
describe 9 do
it "should be a multiple of 3" do
(9 % 3).should == 0
end
end
# vs
RSpec::Matchers.define :be_a_multiple_of do |expected|
match do |actual|
actual % expected == 0
end
end
describe 9 do
it "should be a multiple of 3" do
9.should be_a_multiple_of(3)
end
end

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describe RSpec, "Syntax"

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Basic Example
describe String do
describe "#upcase" do
it "returns the original string converted to uppercase" do
"hello".upcase.should == "HELLO"
end
it "returns a String" do
"hello".upcase.should be_a(String)
end
it "does not change the original string" do
string = "hello"
string.upcase
string.should_not == "HELLO"
end
end
end

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context / describe
describe "something" do
context "in one context" do
it "does one thing" do
end
end
context "in another context" do
it "does another thing" do
end
end
end

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before / after
describe "before / after" do
before(:each) {}
before(:all) {}
before(:suite) {}
after(:each) {}
after(:all) {}
after(:suite) {}
end
# Before and after blocks are called in the following order:
#
# before suite
# before all
# before each
# after each
# after all
# after suite

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before / after
describe "before / after" do
before(:each) do
@hash = {}
end
it "does something" do
@hash[:key] = "value"
@hash[:key].should_not be_empty
end
end

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let
$count = 0
describe "let" do
let(:count) { $count += 1 }
it "memoizes the value" do
count.should == 1
count.should == 1
end
it "is not cached across examples" do
count.should == 2
end
end

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Implicit subject
describe Array do
describe "when first created" do
it "should be empty" do
subject.should eq([])
end
end
end

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subject
describe Array do
subject { [1,2,3] }
describe "with some elements" do
it "should have the prescribed elements" do
subject.should == [1,2,3]
end
end
end

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expect
describe Integer do
describe "#/" do
it "raises ZeroDivisionError when divisor is 0" do
lambda do
1 / 0
end.should raise_error(ZeroDivisionError)
end
end
end
# vs
describe Integer do
describe "#/" do
it "raises ZeroDivisionError when divisor is 0" do
expect {
1 / 0
}.to raise_error(ZeroDivisionError)
end
end
end

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Shared Behaviors
shared_examples "a collection" do
let(:collection) { described_class.new([7, 2, 4]) }
context "initialized with 3 items" do
it "says it has three items" do
collection.size.should eq(3)
end
end
describe "#include?" do
context "with an an item that is in the collection" do
it "returns true" do
collection.include?(7).should be_true
end
end
context "with an an item that is not in the collection" do
it "returns false" do
collection.include?(9).should be_false
end
end
end
end

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Shared Behaviors
describe Array do
it_behaves_like "a collection"
end
describe Set do
it_behaves_like "a collection"
end

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pending
describe Hash do
it "adds a key" do
{ :key => "value" }[:key].should == "value"
end
it "does something unknown"
it "does something buggy" do
pending "This method is buggy"
end
end
describe Integer do
before(:each) { pending }
it "computes 1 + 1" do
(1 + 1).should == 2
end
it "computes 1 - 1" do
(1 - 1).should == 0
end
end

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pending
describe "an example" do
xit "is pending using xit" do
true.should be(true)
end
end
describe "an example" do
it "checks something" do
(3+4).should == 7
end
pending do
"string".reverse.should == "gnirts"
end
end

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Metadata
describe "something", :this => { :is => :arbitrary } do
it "does something", :and => "so is this" do
# ...
end
end
RSpec.configure do |c|
c.filter_run_excluding :ruby => lambda {|version|
!(RUBY_VERSION.to_s =~ /^#{version.to_s}/)
}
end
describe "something" do
it "does something", :ruby => 1.8 do
# ....
end
it "does something", :ruby => 1.9 do
# ....
end
end

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Metadata
c.filter_run :focus => true
end
describe "something", :focus => true do
# ....
end
end
c.filter_run_excluding :slow => true
end
describe "something", :slow => true do
# ....
end
end

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describe RSpec, "Integration"

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RSpec

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describe AccountsController do
describe "GET show" do
before(:each) do
get :show
end
it { should respond_with :success }
it { should render_template "accounts/show" }
it "assigns user" do
assigns(:user).should == @user
end
end
end
RSpec
# Gemfile
group :development, :test do
gem 'rspec-rails', '~> 2.6.0'
end
spec folder

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RSpec
RSpec.configure do |config|
config.include Rack::Test::Methods
end
describe Tremonti::Application do
def app
Tremonti::Application
end
describe "/" do
it "should respond with 200" do
get "/"
last_response.should be_ok
last_response.body.should == "Hello from RoboFinance!"
end
end
end
rack-test

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RSpec Mocha
RR
RSpec.configure do |config|
# == Mock Framework
#
# If you prefer to use mocha, flexmock or RR, uncomment the appropriate line:
#
config.mock_with :mocha
# config.mock_with :flexmock
# config.mock_with :rr
end

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RSpec Factories
describe BillingCharge do
subject { Factory.build(:billing_charge) }
describe "associations" do
it { should belong_to(:user) }
end
describe "validations" do
it "is valid with factory" do
Factory.build(:billing_charge).should be_valid
end
it { should validate_presence_of(:user_id) }
it { should validate_format_of(:period).with('2010-02') }
it { should validate_format_of(:period).not_with('201002') }
it { should validate_format_of(:period).not_with('2010') }
end
end

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describe RSpec, "Best Practices"

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describe vs context
describe ".guess" do
it "recognizes tld" do
s = Whois::Server.guess(".com")
s.should be_a(Whois::Server::Adapters::Base)
s.type.should == :tld
end
context "when the input is a tld" do
it "returns a IANA adapter" do
Whois::Server.guess(".com").should ==
Whois::Server.factory(:tld, ".", "whois.iana.org")
end
end
context "when the input is a domain" do
it "lookups definitions and returns the adapter" do
Whois::Server.guess("example.test").should ==
Whois::Server.factory(:tld, ".test", "whois.test")
end
end
end

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it vs specify
describe User do
before do
@user = User.new :username => 'weppos'
end
it "is not an administrator" do
@user.should_not be_admin
end
end
# vs.
describe User do
let(:user) do
User.new :username => 'weppos'
end
specify do
user.should_not be_admin
end
end

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should
describe "#order_price" do
it "should be a Money" do
# ...
end
it "should return nil when amount is blank" do
# ...
end
end
# vs
describe "#order_price" do
it "is a Money" do
# ...
end
it "returns nil when amount is blank" do
# ...
end
end

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context vs it
describe Hash, "#size" do
it "returns 0 when the Hash is empty" do
end
it "returns the number of elements when the Hash is not empty" do
end
end
# vs
describe Hash, "#size" do
context "when the Hash is empty" do
it "returns 0" do
end
end
context "when the Hash is not empty" do
it "returns the number of elements" do
end
end
end

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Instance vs Class methods
describe Time do
describe ".parse" do
it "converts given string into a Time" do
Time.parse('2010-06-12').should == Time.mktime(2010, 06, 12)
end
end
describe "#to_i" do
it "returns the timestamp corresponding to the Time object" do
t = Time.mktime(2010, 06, 12)
t.to_i.should == 1276293600
end
end
end

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Testing with RSpec (RubyDay 2011)

Testing with RSpec (RubyDay 2011)

Simone Carletti

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