Lecture 3. Miscellaneous Ruby and Testing 1 / 48

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1 Lecture 3 Miscellaneous Ruby and Testing 1 / 48

2 Homework 1 Grades were released! TAs provided feedback on best practices, but did not take off points Keep the comments in mind for future assignments! Any questions? 2 / 48

3 Homework 2 Homework 2 was due last night Any questions? 3 / 48

4 How would you rate the di culty of Homework 2? Vote at 4 / 48

5 CIS 19x Lecture This week's lecture was on How the Web Works It was the last one Questions from the lecture? 5 / 48

6 What does git clone do? Makes a clone of a specific file Makes a clone of a specific folder Clones an existing repository into a new directory This isn't a real git command Vote at 6 / 48

7 What does git add do? Specifies that you would like to include updates made on the provided file in the next commit Adds a file to your remote Git repository Add text to an existing file This isn't a real git command Vote at 7 / 48

8 What does git commit do? Commits your staged files to the project history locally Commits your staged files to the project history remotely (i.e. GitHub repository) This isn't a real git command Vote at 8 / 48

9 What does git push do? Pushes changes from your remote repo to your local directory Pushes your committed changes to your remote repo This isn't a real git command Vote at 9 / 48

10 O ce Hours Weekday Time TA Location Monday 5-7 Zhilei Moore 100 Tuesday 6-8 Edward Harrison Mezz 8-10 Sanjana Harrison Mezz Wednesday 7-9 Zena Moore 100 Thursday 5-7 Desmond Moore / 48

11 Variables 11 / 48

12 Constants Constants start with a capital letter By convention, they should be in all upper case and separated with underscores Like variables, but their value should never be changed once set Ruby will allow you to change them, but it will output a warning They can be accessed from another class or module with :: class Foo BAR = 'bar' end p Foo::BAR #=> "bar" 12 / 48

13 Global Variables Denoted with a $ in the beginning of the identifier They are accessible throughout the entire Ruby program and never go out of scope They generally provide information you would want regardless of where in the program you are For example, $0 returns the name of the startup file for the program You should never create new global variables unless you know what you're doing 13 / 48

14 Regular Expressions 14 / 48

15 Regular Expressions Regular expressions are usually instantiated with // from the Regexp class They match patterns For example, if I wanted to find all letters in the string h3l1o w0r1d: 'h3l1o w0rld'.scan(/[a-za-z]/) #=> ["h", "l", "o", "w", "r", "d"] And if I wanted to find all numbers: 'h3l1o w0rld'.scan(/[0-9]/) #=> ["3", "1", "0"] 15 / 48

16 Methods to Match String#scan Returns an array of all matches Returns an empty array if there is no match String#=~ or Regexp#=~ Returns the index where the Regexp matches the string Returns nil if there is no match String#match or Regexp#match Returns a MatchData object that can be used to get more info about the match Returns nil if there is no match 16 / 48

17 How to Write Regexes Use Rubular You can match with: literal characters dot wildcard characters character classes 17 / 48

18 Literal Characters The exact characters in the regular expression are used 'abcd'=~ /a/ #=> 0 'abcd'=~ /ab/ #=> 0 'abcd'=~ /ac/ #=> nil 18 / 48

19 Dot Wildcard Characters Using a dot (.) will match any character in that place To match for an actual dot, escape it with the backslash (\) This is also true for any other special characters (\, #, +) 'cat bat data'.scan(/.at/) #=> ["cat", "bat", "dat"] 'hello. loco. world'.scan(/.o\./) #=> ["lo.", "co."] 19 / 48

20 Character Classes A list of characters can be denoted with square brackets ([]) 'cat bat sat'.scan(/[cb]at/) #=> ["cat", "bat"] These also support ranges with a hyphen (-) To search for all letters, use [a-za-z] 'hi Bye'.scan(/[a-hB-G]/) #=> ["h", "B", "e"] 20 / 48

21 Common Character Classes Instead of constantly typing out the same list of character classes, some have been abstracted into special characters For example: \s denotes whitespace characters \d denotes digits \w denotes word characters (letter, number, underscore) '12hello3'.scan(/\d/) #=> ["1", "2", "3"] 21 / 48

22 Command Line Interfaces 22 / 48

23 Interacting with Users Use the gets method to collect user input The program will halt while it waits for the user to type in input The input will have a newline character at the end (because the user has to press enter) Call strip on the output of gets to get rid of any whitespace at the beginning or end gets allows us to create dynamic command line interfaces 23 / 48

24 Testing 24 / 48

25 Why do we write tests? Vote at 25 / 48

26 Why do we write tests? Determine that our code provides expected output For expected cases and edge cases Allows us to refactor confidently They make for good documentation Improve design 26 / 48

27 Test-Driven Development (TDD) Process that involves writing tests before writing the code being tested Steps: 1. Write a very small test for code that does not yet exist 2. Run the test & watch it fail 3. Write just enough code to make the test pass 4. Once the test passes, refactor as necessary 5. Repeat 27 / 48

28 Behavior-Driven Development (BDD) Started as a way to better understand & explain TDD Puts the focus on behavior instead of structure BDD Triad Given some context When some event occurs Then I expect some outcome 28 / 48

29 Ruby Testing Frameworks MiniTest RSpec* Cucumber 29 / 48

30 RSpec RSpec is a productive Ruby test framework Made of three independent gems: rspec-core: overall test harness that runs the specs rspec-expectations: provides a readable, powerful, syntax, for checking properties of your code rspec-mocks: makes it easy to isolate code being tested from the rest of system 30 / 48

31 Getting Started gem install rspec Run rspec --init Creates a.rspec file Creates spec/spec_helper.rb which contains configuration options 31 / 48

32 Specs RSpec tests are known as specs Short for specifications because they "specify" the desired behavior of your code Specs are placed in files ending in _spec.rb inside of the spec directory Specs serve two purposes: Documenting what the object can do Checking that the object does what it's supposed to 32 / 48

33 Running Specs Run tests by running the rspec command Running specific directories/files: rspec spec/{directory/file_name} 33 / 48

34 Example Groups You create example groups in RSpec using describe Example groups define what you're testing & keep related specs together You can pass a string, Ruby class, module, or object to describe describe User do describe '#valid?' do... end end 34 / 48

35 Examples You create examples using it Pass it the description of the behavior you're specifying describe User do describe '#valid?' do it 'returns true if the user is valid' do... end end end 35 / 48

36 context context is an alias for describe Groups together examples that are related to a shared situation or condition Useful to improve readability describe User do describe '#valid?' do context 'when the user is valid' do it 'returns true' do... end end end end 36 / 48

37 Expectations Expectations are like assertions in other languages Each RSpec example should contain at least one expectation Most of the time they should contain exactly one (unit tests) Primary goal is for clarity 37 / 48

38 Expect You create expectation using expect Parts: Subject - what's being tested Matcher - an object specifying what you expect to be true about the subject Custom Failure Message - this is optional expect(user.valid?).to be true, 'user is not valid' expect(user.valid?).to_not be true, 'user is valid' expect(user.valid?).not_to be true, 'user is valid' 38 / 48

39 Matchers Similar to regular expressions Define a category of objects that meet a certain specification List of Built-In Matchers expect(a).to eq(b) expect(a).to be(b) expect(a).to_not be_empty expect(a).to include(b) expect { a }.not_to output(b).to_stdout 39 / 48

40 Would this test pass? it 'does not include the number 3' do expect([1, 2, 4, 5]).to_not include(3) end Vote at 40 / 48

41 How about this test? it 'prints out hi' do expect { print 'hello' }.to output('hi').to_stdout end Vote at 41 / 48

42 Hooks Great for common setup/teardown code Types specify when the hook should run relative to the examples: before will run before an example/example group after will run after an example/example group around will sandwich an example Scope allows you to specify how often the hook gets run :each will run once per example (default) :all will run once per example group 42 / 48

43 Hooks before(:each) do... end after(:all) do... end around do... example.run... end 43 / 48

44 let let binds a name to the result of a computation They are useful for assigning variables at the beginning of an example group describe User do describe '#valid?' do let(:user) { User.new } it 'is not valid without a name' do expect(user.valid?).to be false end end end 44 / 48

45 Resources RSpec API Documentation RSpec Built-In Matchers Better Specs 45 / 48

46 Test Coverage We want to strive for 100% test coverage Can use the simplecov gem to check coverage To use: Add gem 'simplecov', require: false to testing group of Gemfile and bundle install Add the following at top of spec/spec_helper.rb: require 'simplecov' SimpleCov.start Run tests and open coverage/index.html file in browser 46 / 48

47 Homework 3 You will be writing tests for three fully intact classes Grading: Correctness (15pts): Must have at least one test for every method (5pts) All tests must pass (5pts) Must reach 100% test coverage (5pts) Style (5pts) Best Practices (5pts) 47 / 48

48 Next Week: Ruby on Rails! 48 / 48

Lecture 3. Miscellaneous Ruby and Testing 1 / 40

Lecture 3. Miscellaneous Ruby and Testing 1 / 40 Lecture 3 Miscellaneous Ruby and Testing 1 / 40 Homework 1 Grades were released! TAs provided feedback on best practices, but did not take off points Keep the comments in mind for future assignments! Any