Intro to RSpec methods

1. Rspec 101 Jason Noble http://jasonnoble.org

2. Example Group describe() Defines example group of tests String we pass describes the item we’re testing it() Defines a code example String we pass describes the specific behaviour

3. describe() Method describe “A User” {…} A User describe User {…} User describe User, “with no roles assigned” {…} User with no roles assigned

4. Describe blocks can be nested

5. context() method context() is an alias for describe() Use describe() for things, context() for context

6. it() method Argument should state what is being tested

7. Pending tests We can mark tests to be implemented “later”

8. Pending tests (cont.) Each method of marking a test as pending has its usefulness: Add pending examples as you think of stuff to test Disable failing examples without losing track that you need to fix those at some point Wrap failing examples when you want to be notified when changes to the system cause them to pass (bug is fixed, etc)

9. before()/after() method Before/after methods helps you set and/or reset initial state Create a new stack, add one element to it Takes one argument :each Executes this block before each test group executes :all Executes this block once for all tests before the first test is run

10. before(:each) method

11. before(:all) Method is run once and only once for a group of tests Be careful using this method, usually we want each test to have it’s own environment setup Sharing state between examples can cause unexpected things Good examples: Opening a network connection Pre-seeding caches

12. after(:each) method Code is ran after each example Rarely necessary because each example runs in its own scope, and consequently the instance variables in that scope are reset Can be useful to reset global state of things after your test completes after(:each) is guaranteed to run after each example, even if failure or errors are raised

13. after(:each) example

14. after(:all) method This is even more rare than the after(:each) Examples: Close down browsers Close database connections Close sockets Any resource we want to release when we’re done, but not after every individual test

15. around(:each) method Supports APIs that require a block Very rarely, if ever used I have never used this Put your functionality into before/after blocks if at all possible See http://relishapp.com/rspec/rspec-core/v/2-0/dir/hooks/around-hooks if you’re interested

16. Helper Methods Defined within an example group Available to all examples in the group

17. Shared Helper Methods If helper methods need to be used across example groups, put them in one or more modules and include modules in example groups we want to have access

18. Shared Examples If we expect instances of more than one class to behave in the same way, a shared example group describes the behavior once and includes it in multiple example groups

19. Shared examples (cont.)

20. RSpec::Expectations One goal of BDD is getting the words right Expectations vs. Assertions We are setting an expectation of what should happen rather than what will happen In fact the word should is part of RSpec result.should equal(5) message.should match(/on Sunday/)

21. should, should_not and matchers result.should equal(5) If result is equal to 5, it passes result.should_not equal(5) If result is anything other than 5, it passes General Pattern:result.should ________(value) _______ is a matcher

22. RSpec built in Matchers include(item) prime_numbers.should_not include(8) respond_to(message) list.shouldrespond_to(:length) raise_error(type) lambda { Object.new.explode! }.should raise_error(NameError)

23. 4 ways to be equal a == b Value equality (Most common) a === b Is Object a the same Object as b a.eql?(b) Are a and b values equal and of same type a.equal?(b) Is Object a the same Object as b (General Rule: The longer the method name, the more restrictive the matcher is)

24. Do not use != in expectations actual.should != expected action.should_not == expected Causes issues, explained in detail in the RSpec book

25. Floating Point Calculations “expected 5.25 got 5.251” is frustrating in a failure message RSpec offers a be_close matcher that accepts an expected value and an acceptable delta result.shouldbe_close(5.25, 0.005) Will pass as long as result is within .005 of 5.25

26. Matching Text response.should match(/this expression/) Matches if response has text “this expression” somewhere in its contents response.should =~ /this expression/ Functionally equivalent to the previous one

27. Expect{} Tests that a block of code causes some effect You can also use .to(1) or .from(0).to(1)

28. Predicate Matchers How do we test array.empty? array.empty?.should == true array.shouldbe_empty

29. Predicate matchers (cont.) RSpec gives you other options be_ be_a ted.shouldbe_a_kind_of(Player) => ted.kind_of?(Player) be_an ted.shouldbe_an_instance_of(Player) =>ted.instance_of?(Player) RSpec also lets you write your own matchers

30. Matchers have_ becomes has_ request_params.shouldhave_key(:id) =>request_params.has_key?(:id).should == true

31. specify{} Sometimes RSpec can guess your tests it “should have 32 pieces” do @board.should have(32).piecesend specify { @board.should have(32).pieces } This is used rarely (very simple tests)

32. subject {} Clean up your tests by specifying a subject

33. RSpec Mocks Mocks allow you to fake functionality that isn’t being tested. See the book for more info.

34. rspec command rspec –help List options available to running RSpec rspec spec/simple_math_spec.rb Run only one spec file rspec spec Run all specs in spec/ directory rspec spec --format documentation Makes RSpec more verbose with test output

35. rspec commands (cont.) rspec spec –color Passing is green, pending is yellow, fail is red Store common options in .rspec file --color --format documentation Options stored in ./.rspec take precedence over ~/.rspec, options declared command line win

36. Let’s get started mkdir -p calculator/{lib,spec} cd calculator mate .

37. spec/calculator_spec.rb lib/calculator.rb

38. spec/calculator_spec.rb