RSpec expectations

gistfile1.txt

Index:
1. should() #basic expectation

2. should_not() #basic negation of an expectation (RSpec does not support using !=)

3. include(item) #called on an enumerable object, this returns true or false if the object is found in the enumerable collection

4. respond_to(:message) #determines if a particular message (as a symbol) is defined for an object

5. raise_error(type, message) #checks if a particular error was raised, accepts zero, one or two parameters

6. == #value equality

7. eql #self and other have the same values, and type

8. equal #self and other have the same object id

9. =~ #matches against a regular expression

10. match(/regex/) #matches against a regular expression

11. be_close(value, range of tolerance) #determines if value is within the acceptable range (useful for floating point calculations)

12. expect {
      given condition
    }.to change{then condition}.by(difference in change)

13. throw_symbol() # accepts zero, one or two arguments (like raise_error())

14. be_predicate() # equates predicate to a predicate method ex. empty? => be_empty()

15. be_a_predicate || be_an_predicate #equates to a predicate just as does rule 14

16. be_true() # return values should be evaluated as true or false (it doesn't mean the return value is a boolean)

17. be_false() # return values should be evalauted as true or false  (it doesn't mean the return value is a boolean) only time Ruby evaluates to false is `false` and nil

18. have_key() # equates to a Hash.has_key?(:item) method (like be_predicate()) - works on any method beginning with has_

19. have().collection_item_to_check # used on collections, collection_item_to_check is the attribute of the collection to check size or length with, if this method isn't found
                                    # RSpec ignores the collection_item_to_check and evalutates the length or size of the target object, assuming it has a length or size method defined on it

20. have() # used on Strings

21. collection precision

    have_exactly(number)
    have_at_least(number)
    have_at_most(number)

22. operators

    <
    >
    <=
    >=

23. subject of an example is the object being described

24. should_receive(:method_name).with(arg).and_return(arg)

Examples:
1. a.should == b

2. a.should_not == b

3. prime_numbers.should_not include(8)

4. list.should respond_to(:length)

5. lambda { Object.new.explode! }.should raise_error(NameError)

5. account = Account.new 50, :dollars
   expect {
     account.withdraw 75, :dollars
   }.to raise_error(InsufficientFundsError, /attempted to withdraw 75 dollars from an account with 50 dollars/) #this line and following 3 lines demonstrate all possible ways to invoke raise_error()
   }.to raise_error(InsufficientFundsError)
   }.to raise_error("attempted to withdraw 75 dollars from an account with 50 dollars")
   }.to raise_error(/attempted to withdraw 75 dolalrs from an account with 50 dollars/)

6. a.should == b

7. a.should eql(b) #self and other have the same values, and type

8. a.should equal(b) #self and other have the same object id

9. result.should =~ /Total Due: \$37\.42/m

10. result.should match(/this expression/)

11. result.should be_close(5.25, 0.005) #result passes as long as the value is withint .005 of 5.25

12. expect {
      seller.accept Offer.new(250_000)
    }.to change{agent.commission}.by(7_500)

# useful for testing against database transactions
12. expect {
      User.create!(role: "admin")
    }.to change( User.admins.count ).by(1)

13. course = Course.new(seats: 20)
    20.times { course.register Student.new }
    lambda {
      course.register Student.new
    }.should throw_symbol(:course_full)

14. array.empty?.should == true
    should be expressed as:
    array.should be_empty

16. true.should be_true
    0.should be_true
    "this".should be_true

17. false.should be_false
    nil.should be_false

18. request_parameters.has_key?(:id).should == true
    # can be rewritten as:
    request_paramaters.should have_key(:id)

19. collection.should have(37).items #items is syntactic sugar

20. "this string".should have(11).characters #characters is syntactic sugar for strings

21. day.should have_exactly(24).hours
    dozen_bagles.should have_at_least(12).bagels
    internet.should have_at_most(2037).awesome_social_networking_apps

22. result.should be < 7
    result.should be > 7
    result.should be <= 7
    result.should be >= 7

23. describe Person do
      subject { Person.new(birthdate: 19.years.ago) }
      specify { subject.should be_eligible_to_vote }
      OR
      it { should be_eligible_to_vote }
      OR
      it "should be eligible to vote" do
        subject.should be_eligible_to_vote
      end
    end

24. describe Person do
      subject { Person.new }
      specify { subject.should_receive(:birthday).with(19).and_return(19) }