TestingTesting In Rails 1 Alan and Saskia 282008

Testing/Testing In Rails 1 Alan and Saskia 2/8/2008

Outline • • • Testing In General Unit Testing and Test First! Integration Testing Functional Testing Fixture Mocking with Mocha

Testing In General (1) • Formal Definition – Testing is the process of finding differences between the expected behavior specified by system models and the observed behavior of the implemented system. – The goal is to design tests that exercise defects in the system and to reveal problems

Testing In General (2) • Alternative Definition – Testing has to demonstrate that faults are not present at all. • Almost impossible to show • May lead to the selection of test data that have a low probability of causing the program to fail • Even more alternative (Wilson Bilkovich) – Writing applications without tests makes you a bad person, incapable of love.

Types of Testing (1)

Types of Testing (2)

Unit Testing in Ruby • Unit Testing – Testing small units of codes (normally methods) • Test: : Unit – Ruby’s built-in testing framework – x. Unit family (Java’s Junit, . NET’s Nunit) • Concepts – Assertions: comparison of expected value and result of an expression – Failure: assertion failure – Error: exception or runtime error – Green vs red bar

Unit Testing in Ruby (2) require 'roman' <<Class inclusion require 'test/unit' class Test. Roman < Test: : Unit: : Test. Case <<super class def setup <<code to be run before all test methods end <<naming convention def test_simple assert_equal("i", Roman. new(1). to_s) <<assertions assert_equal("ix", Roman. new(9). to_s) end def teardown end <<code to be run after all test methods

Assertions (1) • assert(boolean, [ message ] ) – Fails if boolean is false or nil. • assert_nil(obj, [ message ] ) • assert_not_nil(obj, [ message ] ) – Expects obj to be (not) nil. • assert_equal(expected, actual, [ message ] ) • assert_not_equal(expected, actual, [ message ] ) – Expects obj to equal/not equal expected, using ==. • assert_in_delta(expected_float, actual_float, delta, [ message ]) – Expects that the actual floating-point value is within delta of the expected value.

Assertions (2) • assert_raise(Exception, . . . ) { block } • assert_nothing_raised(Exception, . . . ) { block } – Expects the block to (not) raise one of the listed exceptions. • assert_instance_of(klass, obj, [ message ] ) • assert_kind_of(klass, obj, [ message ] ) – Expects obj to be a kind/instance of klass. • assert_respond_to(obj, message, [ message ] ) – Expects obj to respond to message (a symbol). • assert_match(regexp, string, [ message ] ) • assert_no_match(regexp, string, [ message ] ) – Expects string to (not) match regexp. • assert_same(expected, actual, [ message ] ) • assert_not_same(expected, actual, [ message ] ) – Expects expected. equal? (actual).

Assertions (3) • assert_operator(obj 1, operator, obj 2, [ message ] ) – Expects the result of sending the message operator to obj 1 with parameter obj 2 to be true. • assert_throws(expected_symbol, [ message ] ) { block } – Expects the block to throw the given symbol. • assert_send(send_array, [ message ] ) – Sends the message in send_array[1] to the receiver in send_array[0], passing the rest of send_array as arguments. Expects the return value to be true. • flunk(message="Flunked") – Always fail.

Test First! • What is it about? – Write the test cases first. Then write minimal codes to pass the tests – Write more tests. Write more minimal codes to pass the tests – Iterate the process till all functional requirements are satisfied

Test First Guidelines • The name of the test should describe the requirement of the code • There should be at least one test for each requirement of the code. Each possible path through of the code is a different requirement • Only write the simplest possible code to get the test to pass, if you know this code to be incomplete, write another test that demonstrates what else the code needs to do • A test should be similar to sample code, in that it should be clear to someone unfamiliar with the code as to how the code is intended to be used • If a test seems too large, see if you can break it down into smaller tests • If you seem to be writing a lot of code for one little test, see if there are other related tests you could write first, that would not require as much code • More at http: //www. xprogramming. com/xpmag/test. First. Guidelines. htm

Test First Demo

Unit Testing in Rails • In rails, unit testing is geared towards testing of individual functions created in a model • For each model generated, a test file is automatically created in tests/unit directory • script/generate model product name: string description: string exists app/models/ exists test/unit/ exists test/fixtures/ create app/models/product. rb create test/unit/product_test. rb ….

Testing/Testing In Rails 1 Saskia Outline • • • Testing In General Unit Testing and Test First! Integration Testing Functional Testing Fixture Mocking with Mocha

Types of Testing (1)

Integration Testing in Ro. R • Integration Testing – story-level, tests interactions & interfaces of various actions supported by the application, across all controllers – Find bugs with session management and routing, triggered by certain cruft accumulating in a user’s session • In 'test/integration': – Create test file with 'script/generate integration_test stories_test' – Class Integration. Test inherits from Test: : Unit

Integration Testing in Ro. R • Story set describes how the application ought to function – Interfaces: exchange of right data – Interaction: employment of right components • Example: signing up, getting account, multiple users • Testing time grows with number of integrated units – Bottom-Up: Integrate tested Units to subsystems as new components

Integration Testing in Ro. R File 'stories_test. rb' in 'test/integration': require "#{File. dirname(__FILE__)}/. . /test_helper" <<class inclusion class Stories. Test < Action. Controller: : Integration. Test <<Integration Test Class fixtures : users, : accounts def test_stories <<naming convention get "/signup" assert_response : success <<assertions assert_template "signup/index" post "/signup", : name => "Bob", : user_name => "bob", : password => "secret" assert_response : redirect follow_redirect! assert_response : success assert_template "account/index" end

Integration Testing in Ruby (2) Run by: rake test_integration or ruby stories_test. rb Output: Started <<Each spot represents a test, sorted alphabetically, . F. . E 3 values: . means successful test (pass) Finished in 0. 01 seconds. F means failed test E means an error occurred 1) Failure: where/which test what went wrong 2) Error: where/which test error_type what went wrong <<Listing of failures & errors: Details on where and what Moves on with first wrong assertion. 5 tests, 9 assertions, 1 failure, 1 error.

Types of Testing (1)

Functional Testing in Ruby • Functional Testing – single controllers and interactions between the models it employs • In directory 'test/function': – 'functional_controller_test. rb' stubs for each 'script/generate controller'

Functional Testing in Ro. R require File. dirname(__FILE__) + '/. . /test_helper' require 'home_controller' << grab Home. Controller for testing class Home. Controller. Test < Test: : Unit: : Test. Case def setup << setup of 3 typical funtional Test objects: * controller to be tested @controller = Home. Controller. new * Test. Request to @request = Action. Controller: : Test. Request. new simulate web request @response = Action. Controller: : Test. Response. new * Test. Response to provide information about test request end def test_index << test of main index page << get method simulates request on action called index get : index assert_response. : success << assertion assures that request successful end 5 request types supported as methods in Rails: end get, post, put, head, delete

Fixtures in Ro. R • Fixtures: automatically created sample data – To fill testing database with predefined data before tests run – database independent – Require explicit loading with fixtures method within test class • In directory 'test/fixtures': – fixture stubs for each 'script/generate model' • Formats – YAML: good readability, file extension '. yml' – CSV: comma-separated value file format, '. csv', easy reuse of existing data in spreadsheet/database (save/export as CSV)

YAML-Fixtures File 'persons. yml' of YAML-Fixtures in 'text/fixtures': # This is a YAML comment! david: << name 1 id: 1 name: David Dwarf birthday: 0010 -01 -01 profession: slingshoter goliath: << name 2 id: 2 name: Goliath Giant birthday: 0000 -02 -22 profession: terrorizer << list of values << fixture-records separated by blank line each fixture: * 'fixture-name' * list of colon-separated key/value pairs

CSV-Fixtures File 'users. csv' of CSV-Fixtures in 'text/fixtures': << header: first line, commaid, username, password, intelligent, comments separated list of fields 1, dhow, imstupid, false, I laugh ""Ha! Ho! Hu!"" 2, admin, ihatedhows, true, What a mess! << list of value-records, 3, nobody, ilovetomock, true, "Nobody mocks you" one record per line format: 4, nulpe, , false, * each cell stripped of outward facing spaces * comma as data: cell must be encased in quotes * quote as data: must escape it with 2 nd quote * no blank lines * nulls achived by placing comma CSV fixture names automatically generated: “model-name”-”counter” users-1 users-2. . .

Fixtures in Action # allow this test to hook into the Rails framework require File. dirname(__FILE__) + '/. . /test_helper' # need to include a User for testing require 'user' class User. Test < Test: : Unit: : Test. Case fixtures : users << fixture-load method: * destroys any data in users table * loads fixture data into users table def test_count_fixtures * dumps the data into a variable for direct access assert_equal 5, User. count end automatic load of the fixtures at the start of each test method

Hashes with Fixtures are basically Hash objects: - direct access via generated local variable of the test case Fixtures can get form of the original class: - access to methods only available to that class. . . fixtures : users, : person << load multiple fixtures separated by commas def test_users(: nobody) << returns Hash for fixture named david users(: nobody). id << returns id-property of david end def test_person david = users(: david). find << using find method to grab "real" david as Person email( david. girlfriend. email, david. illegitimate_children ) <<now: access to methods only available to a Person class end. . .

Mocking with Mocha • Problem with Fixtures – Fixtures makes testing slow (engage the actual DB) – Fixtures allow invalid data – Maintainability Challenges – Fixtures are brittle • That’s why we need Mocha (http: //mocha. rubyforge. org/) – It provides stubs and mocks to simulate data, especially data in the database

Installing Mocha • sudo gem install mocha • In rails, include in test/test_helper. rb require ‘mocha’

Do Not Mock My Stub • Stubbing (State Verification) – Stubbing a method is all about replacing the method with code that returns a specified result (or perhaps raises a specified exception). • Mocking (Behavior Verification) – Mocking a method is all about asserting that a method has been called (perhaps with particular parameters). • it’s difficult (or impossible? ) to do mocking without stubbing you need to return from the mocked method, so that the code under test can complete execution • http: //www. martinfowler. com/articles/mocks. Arent. Stubs. htm l

Stubbing example (stub) require 'test/unit' require 'rubygems' require 'mocha' class Test. Product < Test: : Unit: : Test. Case def test_product = stub('ipod_product', : manufacturer => 'ipod', : price => 100) assert_equal 'ipod', product. manufacturer assert_equal 100, product. price end

More stubbing example (stubs) class View attr : document def initialize(document) @document = document end def print() if document. print puts "Excellent!" true else puts "Bummer. " false end end require 'test/unit' require 'rubygems' require 'mocha' class View. Test < Test: : Unit: : Test. Case def test_should_return_false_for_failed_print document = stub("my document") document. stubs(: print). returns(true) ui = View. new(document) assert ui. print end

Mocking example (expects) class Enterprise def initialize(dilithium) @dilithium = dilithium end def go(warp_factor) warp_factor. times { @dilithium. nuke(: anti_matter) } end require 'test/unit' require 'rubygems' require 'mocha' class Enterprise. Test < Test: : Unit: : Test. Case def test_should_boldly_go dilithium = mock() dilithium. expects(: nuke). with(: anti_matter). at_least_once enterprise = Enterprise. new(dilithium) enterprise. go(2) end

Expects More Mocking • Methods in expects: – at_least, at_least_once, at_most_once, in_sequence, multiple_yields, never, once, raises, returns, then, times, when, with, yields