w2d5 Flashcards
What is a DSL?
A domain-specific language; used for a specific problem domain.
What is the logic behind RSpec not testing private classes?
Private methods should support the public interface, so testing public methods should suffice.
What is the directory structure for projects with RSpec?
my_cool_project
lib/
hello.rb
spec/
hello_spec.rbWhat requires must spec files have?
They must require ‘rspec’ and the name of the file they are testing.
What is the ‘context’ keyword?
An alias for ‘describe’
What is the difference between ‘describe’ and ‘it’?
Both take strings as arguments, but describe takes the name of a method and it takes a description of the behavior being tested in the ‘it’ block
What are uses of the expect method?
expect(test_value).to eq(‘5’)
expect(test_value).to_not raise_error(ArgumentError)
How can we create a shared group of tests?
RSpec.shared_examples “collections” do |collection_class|
How can we use the ‘before’ method?
Use it to set up a context for testing:
before(:each) do
board.make_move([3, 4], [2, 3])
board.make_move([1, 2], [4, 5])
board.make_move([5, 3], [5, 1])
board.make_move([6, 3], [2, 4])
end
T/F: Ruby supports ‘!=’
F
How can we define a subject for our tests?
subject(:robot) { Robot.new }
The symbol can then be accessed as an object:
‘robot.position’
What is the proper TDD workflow
Red, Green, Refactor
Where must the subject of an it block be declared?
Outside the it block.
Say we have a function ‘fibs_rec’, which takes an argument ‘num’, dictating the number of fibonaccis to return. How can we right rspec stating that ‘fibs_rec’ should return the first 2 fibonacci numbers?
it “returns first two fib numbers” do
expect(fibs_rec(2)).to eq([0, 1])
end
Let’s say ‘fibs_rec’ is a recursive function, and we expect it to call itself at least twice. What is the rspec to test this?
it “calls itself recursively” do
expect(self).to receive(:fibs_rec).at_least(:twice).and_call_original
fibs_rec(6)
end
What goes inside a describe ‘string’ do end block?
Various it blocks.
How can we create a variable ‘array’ with a value, and where should it be declared?
let(:array) { [1, 2, 3, 4, 5].shuffle }
It should be inside a do block but before the if blocks that reference it.
How can we create a larger variable to use in rspec, like a large array?
use let (:object_name) do end
let(:dictionary) do
# a small dictionary of words
[“a”, “am”, “an”, “pa”, “pan”, “panama”]
end
What is the difference between ‘let’ and ‘subject’
Subject can only be used once and is the main object for the tests in a describe block, whereas let is used for helper objects and can be used many times, although each time with a different scope for each it block.
What is “memoization”?
Memoization means that the first time the method is invoked, the return value is cached and that same value is returned every subsequent time the method is invoked within the same scope.
Does YAGNI apply when writing RSpec?
Absolutely; focus on getting down fundamental functionality first.
How can we create a double with stub methods?
let(:customer) { double(“customer”, :email_address => “ned@appacademy.io”) }
What is going on here, and how are method expectations set:
describe Order
let(:customer) { double(‘customer’) }
let(:product) { double(‘product’, :cost => 5.99) }
subject(:order) { Order.new(customer, product) }
it “subtracts item cost from customer account” do
expect(customer).to receive(:debit_account).with(5.99)
order.charge_customer
end
end
Here we want to test that when we call charge_customer on an Order object, it tells the customer to subtract the item price from the customer’s account. We also specify that we should check that we have passed #debit_account the correct price of the product.
Notice that we set the message expectation before we actually kick off the #charge_customer method. Expectations need to be set up in advance.
What is distinct about integration tests?
Integration tests uses real objects instead of mocks in order to see if objects interact with one another correctly.
