Mock vs Stubs CleRB Presentation

MOCKS VS STUBS - How will we test this?

WHO AM I?• Attila Domokos• .NET Programmer• Ruby Enthusiast• Twitter: @adomokos• Blog: http://www.adomokos.com• Email:

WHO...??

MOCKS AREN’T STUBS

THE WAREHOUSE EXAMPLE

CALL SEQUENCES

describe Order do before(:each) do @warehouse = Warehouse.new @warehouse.add(:Cleveland, 50) @warehouse.add(:Akron, 25) end it "fills the order with enough items in warehouse" do order = Order.new(:Cleveland, 50) order.fill(@warehouse) order.should be_filled @warehouse.quantity_at(:Cleveland).should == 0 end it "does not fill the order with not enough items" do order = Order.new(:Cleveland, 51) order.fill(@warehouse) order.should_not be_filled @warehouse.quantity_at(:Cleveland).should == 50 endend

USING A MOCKdescribe Order do it "fills the order with enough items in warehouse" do order = Order.new(:Cleveland, 50) warehouse = mock(:warehouse) warehouse.should_receive(:quantity_at).with(:Cleveland).and_return(50) warehouse.should_receive(:set_quantity_at).with(:Cleveland, 0) order.fill(warehouse) order.should be_filled end it "does not fill the order with not enough items" do order = Order.new(:Cleveland, 51) warehouse = mock(:warehouse) warehouse.should_receive(:quantity_at).with(:Cleveland).and_return(50) order.fill(warehouse) order.should_not be_filled endend

USING A STUB - VERBOSEdescribe Order do it "fills the order with enough items in warehouse" do @warehouse.stub!(:quantity_at).and_return(50) @warehouse.stub!(:set_quantity_at).and_return(true) order = Order.new(:Cleveland, 50) order.fill(@warehouse) order.should be_filled end it "does not fill the order with not enough items" do @warehouse.stub!(:quantity_at).and_return(50) @warehouse.stub!(:set_quantity_at).and_return(true) order = Order.new(:Cleveland, 51) order.fill(@warehouse) order.should_not be_filled endend

describe Order do before(:each) do @warehouse = stub(warehouse_stub) setup_stub end it "fills the order with enough items in warehouse" do order = Order.new(:Cleveland, 50) order.fill(@warehouse) order.should be_filled end it "does not fill the order with not enough items" do order = Order.new(:Cleveland, 51) order.fill(@warehouse) order.should_not be_filled endenddef setup_stub @warehouse.stub!(:quantity_at).and_return(50) @warehouse.stub!(:set_quantity_at).and_return(true)end

HOW COOL IS THAT?describe Order do before(:each) do @warehouse = stub(warehouse_stub, {:quantity_at => 50, :set_quantity_at => true}) end it "fills the order with enough items in warehouse" do order = Order.new(:Cleveland, 50) order.fill(@warehouse) order.should be_filled end it "does not fill the order with not enough items" do order = Order.new(:Cleveland, 51) order.fill(@warehouse) order.should_not be_filled endend

CAN WE DO THE SAME?describe Order do it "fills the order with enough items in warehouse" do order = Order.new(:Cleveland, 50) warehouse = mock(:warehouse) warehouse.should_receive(:quantity_at).with(:Cleveland).and_return(50) warehouse.should_receive(:set_quantity_at).with(:Cleveland, 0) order.fill(warehouse) order.should be_filled end it "does not fill the order with not enough items" do order = Order.new(:Cleveland, 51) warehouse = mock(:warehouse) warehouse.should_receive(:quantity_at).with(:Cleveland).and_return(50) warehouse.should_receive(:set_quantity_at).with(:Cleveland, 0) order.fill(warehouse) order.should_not be_filled endend

OH, SNAP!describe Order do it "fills the order with enough items in warehouse" do order = Order.new(:Cleveland, 50) warehouse = mock(:warehouse) warehouse.should_receive(:quantity_at).with(:Cleveland).and_return(50) warehouse.should_receive(:set_quantity_at).with(:Cleveland, 0) order.fill(warehouse) order.should be_filled end it "does not fill the order with not enough items" do order = Order.new(:Cleveland, 51) warehouse = mock(:warehouse) warehouse.should_receive(:quantity_at).with(:Cleveland).and_return(50) warehouse.should_receive(:set_quantity_at).with(:Cleveland, 0) order.fill(warehouse) order.should_not be_filled endend

BUT THIS WORKS!describe Order do it "fills the order with enough items in warehouse" do order = Order.new(:Cleveland, 50) warehouse = mock(:warehouse) warehouse.should_receive(:quantity_at).with(:Cleveland).and_return(50) warehouse.should_receive(:set_quantity_at).with(:Cleveland, 0) order.fill(warehouse) order.should be_filled end it "does not fill the order with not enough items" do order = Order.new(:Cleveland, 51) warehouse = mock(:warehouse) warehouse.should_receive(:quantity_at).with(:Cleveland).and_return(50) warehouse.should_not_receive(:set_quantity_at).with(:Cleveland, 0) order.fill(warehouse) order.should_not be_filled endend

SO WHAT’S THE DIFFERENCE?

NO, SERIOUSLY!• Stubs - Provide canned responses to messages• Mocks - Specify AND verify that certain messages should be received

MOCKS CAN DO MORE!Expecting Messages: my_mock.should_receive(:msg).once my_mock.should_not_receive(:msg).onceExpecting Arguments: my_mock.should_receive(:msg).with(1, 2) my_mock.should_receive(:msg).with(no_args()) my_mock.should_receive(:msg).with(any_args())Argument Constraints: my_mock.should_receive(:msg).with(1, an_instance_of(Fixnum), “b”) my_mock.should_receive(:msg).with(a, boolean(), b) my_mock.should_receive(:msg).with(/abc/)Receive Counts: my_mock.should_receive(:msg).once my_mock.should_receive(:msg).twice my_mock.should_receive(:msg).at_least(:once) my_mock.should_receive(:msg).at_most(:twice) my_mock.should_receive(:msg).any_number_of_timesOrdering: my_mock.should_receive(:one).ordered my_mock.should_receive(:two).ordered

MOCKS CAN DO MOREdescribe Order do it "fills the order with enough items in warehouse" do order = Order.new(:Cleveland, 50) warehouse = mock(:warehouse)warehouse.should_receive(:quantity_at).ordered.with(:Cleveland).and_return(50) warehouse.should_receive(:set_quantity_at).ordered.with(:Cleveland, 0) order.fill(warehouse) order.should be_filled endend

CHANGE THE ORDERdescribe Order do it "fills the order with enough items in warehouse" do order = Order.new(:Cleveland, 50) warehouse = mock(:warehouse) warehouse.should_receive(:set_quantity_at).ordered.with(:Cleveland, 0) warehouse.should_receive(:quantity_at).ordered .with(:Cleveland).and_return(50) order.fill(warehouse) order.should be_filled endend

OH, SNAP!describe Order do it "fills the order with enough items in warehouse" do order = Order.new(:Cleveland, 50) warehouse = mock(:warehouse) warehouse.should_receive(:set_quantity_at).ordered.with(:Cleveland, 0) warehouse.should_receive(:quantity_at).ordered .with(:Cleveland).and_return(50) order.fill(warehouse) order.should be_filled endend

I USED RSPEC MOCKING... ... but there are other libraries:• Flexmock• Mocha• rr

FLEXMOCK - TEST/UNITclass TestOrder < Test::Unit::TestCase def test_fills_order_with_enough_items_at_location order = Order.new(:Cleveland, 50) warehouse = flexmock(warehouse) warehouse.should_receive(:quantity_at).with(:Cleveland).and_return(50) warehouse.should_receive(:set_quantity_at).with(:Cleveland, 0) order.fill(warehouse) assert order.filled? end def test_does_not_fill_order_with_not_enough_items_at_location order = Order.new(:Cleveland, 51) warehouse = flexmock(warehouse) warehouse.should_receive(:quantity_at).with(:Cleveland).and_return(50) order.fill(warehouse) assert order.filled? == false endend

WHEN TO USE MOCKS/STUBS?• Using an external service• Verifying a protocol• Objects are complicated to create

BUT HOWCAN I USE THIS?

MEET TWEETSTATS

TWITTER OAUTH

LOGGED ON

SEND TWEET

VIEW FRIENDS

VIEW FOLLOWERS

ENTER THE SERVICEModel ControllerView OauthService

THE USERS CONTROLLERclass UsersController < ApplicationController before_filter :oauth_login_required, :except => [ :callback, :signout, :index ] def new end...private def oauth_login_required logged_in? || login_by_oauth end... def login_by_oauth redirect_to self.oauth_service.login_by_oauth rescue Exception => e # The user might have rejected this application flash[:error] = "Twitter API failure (account login)" redirect_to root_url endend

STUB IT OUT!describe UsersController do TEST_URL = twitter_test describe "GET new" do it "redirects to twitter - stub example" do # see the extra message stub, I dont need “logged_in?” oauth_service_stub = stub(:login_by_oauth => TEST_URL, :logged_in? => false) controller .stub!(:oauth_service) .and_return(oauth_service_stub) get new response.should redirect_to TEST_URL end endend

STUB IT OUT!describe UsersController do TEST_URL = twitter_test describe "GET new" do it "redirects to twitter - stub example" do # see the extra message stub, I dont need “logged_in?” oauth_service_stub = stub(:login_by_oauth => TEST_URL, :logged_in? => false) controller .stub!(:oauth_service) .and_return(oauth_service_stub) get new response.should redirect_to TWITTER_TEST_URL end endend

OR MOCK ITdescribe UsersController do TEST_URL = twitter_test.com describe "GET new" do it "redirects to twitter - stub example" do ... end it "redirects to twitter - mock example" do oauth_service_mock = mock(:oauth_service) oauth_service_mock .should_receive(:login_by_oauth) .and_return(TEST_URL) controller .stub!(:oauth_service).and_return(oauth_service_mock) get new response.should redirect_to TEST_URL end endend

BUT WHAT’S THE DIFFERENCE? Unused Message Stuboauth_service_stub = stub(:login_by_oauth => TEST_URL, :logged_in? => false) oauth_service_mock = mock(:oauth_service) oauth_service_mock .should_receive(:login_by_oauth) .and_return(TEST_URL)

THIS WILL FAILit "redirects to twitter - mock example" do oauth_service_mock = mock(:oauth_service) oauth_service_mock .should_receive(:login_by_oauth) .and_return(TEST_URL) oauth_service_mock .should_receive(:logged_in) .and_return(false) controller .stub!(:oauth_service).and_return(oauth_service_mock) get new response.should redirect_to TEST_URLend

OH, SNAP!it "redirects to twitter - mock example" do oauth_service_mock = mock(:oauth_service) oauth_service_mock .should_receive(:login_by_oauth) .and_return(TEST_URL) oauth_service_mock .should_receive(:logged_in) .and_return(false) controller .stub!(:oauth_service).and_return(oauth_service_mock) get new response.should redirect_to TEST_URLend

OK, I AM AUTHENTICATEDdef callback user_info = self.oauth_service.get_user_info(params[:oauth_verifier]) @user = User.save_user!({ :twitter_id => user_info[id], :screen_name => user_info[screen_name], :token => self.oauth_service.access_token, :secret => self.oauth_service.access_secret, :profile_image_url => user_info[profile_image_url] }) self.current_user = @user redirect_to @user # Redirect to the show pagerescue Exception => e # The user might have rejected this application. flash[:error] = "Twitter API failure (account login)" redirect_to root_urlend

A NEGATIVE TESTdescribe "Get callback" do it "redirects to the home page when error occurs in service" do # I can use a mock oauth_service = mock(:oauth_service) oauth_service.should_receive(:get_user_info) .once .with(xyz) .and_raise(StandardError) controller.stub!(:oauth_service).and_return(oauth_service) # Exercise get callback, {:oauth_verifier => xyz} flash[:error].should == Twitter API failure (account login) response.should redirect_to root_url endend

OR EXPECT IT TWICEdescribe "Get callback" do it "redirects to the home page when error occurs in service" do # I can use a mock oauth_service = mock(:oauth_service) oauth_service.should_receive(:get_user_info) .twice .with(xyz) .and_raise(StandardError) controller.stub!(:oauth_service).and_return(oauth_service) # Exercise get callback, {:oauth_verifier => xyz} flash[:error].should == Twitter API failure (account login) response.should redirect_to root_url endend

OH, SNAP!describe "Get callback" do it "redirects to the home page when error occurs in service" do # I can use a mock oauth_service = mock(:oauth_service) oauth_service.should_receive(:get_user_info) .twice .with(xyz) .and_raise(StandardError) controller.stub!(:oauth_service).and_return(oauth_service) # Exercise get callback, {:oauth_verifier => xyz} flash[:error].should == Twitter API failure (account login) response.should redirect_to root_url endend

A STUB WILL BE FINEdescribe "Get callback" do it "redirects to the home page when error occurs in service" do # I could use a mock # oauth_service = mock(:oauth_service) # oauth_service.should_receive(:get_user_info) .once.with(xyz) .and_raise(StandardError) # but a stub will exercise the code just fine oauth_service = stub(:oauth_service) oauth_service.stub!(:get_user_info).and_raise(StandardError) controller.stub!(:oauth_service).and_return(oauth_service) # Exercise get callback, {:oauth_verifier => xyz} flash[:error].should == Twitter API failure (account login) response.should redirect_to root_url endend

A POSITIVE TESTit "redirects to the users page after a successful login" do user_info_stub = {id => 123456, screen_name => johndoe, profile_image_url => some_image_url} oauth_service_mock = mock(OauthService, :access_token => 12345, :access_secret => abcde) fake oauth_service_mock.should_receive(:get_user_info) .with(xyz) .and_return(user_info_stub) stub user = User.new dummy mock User.stub!(:save_user!).and_return(user) controller.stub!(:oauth_service).and_return(oauth_service_mock) # Exercise get callback, {:oauth_verifier => xyz} controller.current_user.should == user response.should redirect_to userend

A POSITIVE TESTit "redirects to the users page after a successful login" do user_info_stub = {id => 123456, screen_name => johndoe, profile_image_url => some_image_url} oauth_service_mock = mock(OauthService, :access_token => 12345, :access_secret => abcde) fake oauth_service_mock.should_receive(:get_user_info) .with(xyz) .and_return(user_info_stub) stub user = User.new(:id => 122) dummy mock User.stub!(:save_user!).and_return(user) controller.stub!(:oauth_service).and_return(oauth_service_mock) # Exercise get callback, {:oauth_verifier => xyz} controller.current_user.should == user response.should redirect_to userend

CHECK THE ARGUMENTit "redirects to the users page after a successful login" do user_info_stub = {id => 123456, screen_name => johndoe, profile_image_url => some_image_url} oauth_service_mock = mock(OauthService, :access_token => 12345, :access_secret => abcde) oauth_service_mock.should_receive(:get_user_info) .with(abc) .and_return(user_info_stub) user = User.new(:id => 122) User.stub!(:save_user!).and_return(user) controller.stub!(:oauth_service).and_return(oauth_service_mock) # Exercise get callback, {:oauth_verifier => xyz} controller.current_user.should == user response.should redirect_to userend

OH, SNAP!it "redirects to the users page after a successful login" do user_info_stub = {id => 123456, screen_name => johndoe, profile_image_url => some_image_url} oauth_service_mock = mock(OauthService, :access_token => 12345, :access_secret => abcde) oauth_service_mock.should_receive(:get_user_info) .with(abc) .and_return(user_info_stub) user = User.new(:id => 122) User.stub!(:save_user!).and_return(user) controller.stub!(:oauth_service).and_return(oauth_service_mock) # Exercise get callback, {:oauth_verifier => xyz} controller.current_user.should == user response.should redirect_to userend

AND THE CUCUMBER?

USER LOGIN FEATUREFeature: Login Users In order to access the full site As a user I want to log on to the site with my twitter account Scenario: Login via Twitter Given I am on the home page When I follow "sign_in_with_twitter" And Twitter authorizes me Then I should see "Welcome back!"

WHAT OPTIONS DO I HAVE?• Hit Twitter every time• Stub out my service object• Stub out HTTP

WHAT OPTIONS DO I HAVE?• Hit Twitter every time• Stub out my service object• Stub out HTTP Run test ofﬂine mode

USER_LOGIN_STEPS.RB Scenario: Login via Twitter Given I am on the home page When I follow "sign_in_with_twitter" And Twitter authorizes me Then I should see "Welcome back!" When /^Twitter authorizes me$/ do visit callback_users_path end

ENV.RBrequire fakewebFakeWeb.register_uri(:get, http://twitter.com/oauth/authorize?oauth_token=fake, :body => success)FakeWeb.register_uri(:post, http://twitter.com/oauth/access_token, :body => oauth_token=fake&oauth_token_secret=fake)FakeWeb.register_uri(:get, http://twitter.com/account/verify_credentials.json, :response => File.join(::Rails.root.to_s, features, fixtures, verify_credentials.json))

NEVER GO OUTSIDE!require fakewebFakeWeb.allow_net_connect = falseFakeWeb.register_uri(:get, http://twitter.com/oauth/authorize?oauth_token=fake, :body => success)FakeWeb.register_uri(:post, http://twitter.com/oauth/access_token, :body => oauth_token=fake&oauth_token_secret=fake)FakeWeb.register_uri(:get, http://twitter.com/account/verify_credentials.json, :response => File.join(::Rails.root.to_s, features, fixtures, verify_credentials.json))

VIEW FRIENDS

FRIENDS FEATUREFeature: View Friends In order to see who my friends are As a user I want to go to the friends page and see my friends Background: Given I am logged on to the site Scenario: View friends When I follow "friends" Then I should see "You are following 4 friends."

THE STEPSGiven /^I am logged on to the site$/ do visit callback_users_path view_friends_steps.rbend $: curl -is http://twitter.com/statuses/friends.json? screen_name=adomokos&cursor=-1 > features/ﬁxtures/friends.jsonFakeWeb.register_uri(:get, http://twitter.com/statuses/friends.json?screen_name=adomokos&cursor=-1, :response => File.join(::Rails.root.to_s, features, fixtures, friends.json)) env.rb

CHUCK NORRIS IS HAPPY!

RECAP• Stubs are “Yugos”, Mocks are “Aston Martins”• Stubs are canned answered to messages• Mocks can verify: • If message was sent or not • Input parameters • Order of message• Never go outside of your “box” during automated tests!

MOCKS CAN DO MORE!Expecting Messages: my_mock.should_receive(:msg).once my_mock.should_not_receive(:msg).onceExpecting Arguments: my_mock.should_receive(:msg).with(1, 2) my_mock.should_receive(:msg).with(no_args()) my_mock.should_receive(:msg).with(any_args())Argument Constraints: my_mock.should_receive(:msg).with(1, an_instance_of(Fixnum), “b”) my_mock.should_receive(:msg).with(a, boolean(), b) my_mock.should_receive(:msg).with(/abc/)Receive Counts: my_mock.should_receive(:msg).once my_mock.should_receive(:msg).twice my_mock.should_receive(:msg).at_least(:once) my_mock.should_receive(:msg).at_most(:twice) my_mock.should_receive(:msg).any_number_of_timesOrdering: my_mock.should_receive(:one).ordered my_mock.should_receive(:two).ordered

THANK YOU!

REFERENCES• http://keremerkan.net/qr-code-and-2d-code-generator• http://martinfowler.com/articles/mocksArentStubs.html• http://blog.zerosum.org/2009/7/13/twitter-auth-integration- testing• http://dev.twitter.com/console• http://rspec.info/documentation/mocks/ message_expectations.html

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Mock vs Stubs CleRB Presentation

by Attila Domokos on Dec 12, 2010

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Mock vs Stubs CleRB Presentation — Presentation Transcript