Ken Lee Week 2 and 3 Diagnostic

gistfile1.txt

Week 2 and 3 Diagnostic

This exercise is intended to help you assess your progress with the concepts and techniques we’ve covered during the week.

For these questions, write a short snippet of code that meets the requirement. In cases where the question mentions a “given” data value, use the variable given to refer to it (instead of re-writing the information).

Use single (`) and triple backticks (```) to container code snippets.

Define a class called PizzaOven which has a method cook_pizza which returns the string "mmm 'za".

class PizzaOven
  def cook_pizza
    "mmm 'za"
  end
end

Define a class called Student which is instantiated with a “name” value and which has a method name that returns this value
class
  

end

Given an array of the numbers [1,2,3,4,5], find the sum of the doubles of all the numbers
sum = 0
a = [1,2,3,4,5]
add = a.map { |x| x*2 }
sum_all = add.each { |y| sum+=y }

Give the command to create a new Git repository in a directory on your machine
git init

Pizza

Given a hypothetical Pizza class which has an instance method is_tasty? that always returns true, write a simple Minitest test that tests this behavior.
def test_is_tasty_true
  pizza = Pizza.new
  assert true, pizza.is_tasty?
end
class Pizza
  def is_tasty?
    true
  end
end

Suppose the Pizza class also has a method style which randomly returns one of: "supreme", "mediterranean", or "cheese". Write a test that confirms that the returned pizza style is within this list.
def test_pizza_selection
  pizza = Pizza.new
  x = ["supreme", "mediterranean", "cheese"]
  assert x.include?(pizza.style)
end

def style
  types = ["supreme", "mediterranean", "cheese"]
  types.sample
end

Give the Git commands needed to stage and then commit a set of changes to a file
git commit -m "message"

Student

Define a Student class which, when created, has an attitude attribute. attitude should start out with the value “cheerful”, and the Student class should provide a “reader” method that allows us to access the value of its attitude.

class Student
attr_accessor :attitude #I choose attr_accessor because I assume the student's attitude will change over time but I would go with attr_reader otherwise

 def initialize
  @attitude = "cheerful"
  @descriptions = []
 end
 
 def assign_homework(description)
  @descriptions << description
  if @attitude == "cheerful"
    @attitude = "dubious"
  elsif @attitude == "dubious"
    @attitude = "perturbed"
  else
    @attitude = "dazed"
  end
 end
 
 def assignments
   @descriptions.join(", ")
 end
end

class Student
  def initialize
    @attitudes = ['cheerful', 'dubious', 'perturbed', 'dazed']
    @attitude_counter = 0
  end
  
  def assign_homework
    @attitude_counter += 1 if @attitude_counter < 3
  end
  
  def attitude
    @attitudes[@attitude_counter]
  end
end
    

Additionally, add an assign_homework method to Student. When assign_homework is invoked, if the student’s attitude is "cheerful", it should become "dubious". If the value is currently "dubious" it should become "perturbed". If the value is currently "perturbed", it should become "dazed". Assigning homework to a "dazed" student has no effect.

Building on the Student class from the previous example, update the assign_homework method to accept an argument. The argument will be a String containing a short description of the assignment. For example we might use it like this:

s = Student.new
s.assign_homework("Write a linked list")
Then, add an assignments method to Student. assignments should return a list of all the assignments that have been given, separated by a comma and a space. For example:

s = Student.new
s.attitude
=> "cheerful"
s.assign_homework("write a linked list")
s.attitude
=> "dubious"
s.assign_homework("write a BST")
s.attitude
=> "perturbed"
s.assignments
=> "write a linked list, write a BST"
Given an array of 3 Student instances, generate a new string of all of their assignments
For example:

s1 = Student.new
s2 = Student.new
s3 = Student.new

s1.assign_homework("linked list")
s1.assign_homework("sorting algos")

s2.assign_homework("write a c compiler")
s2.assign_homework("write a pacman game")

s3.assign_homework("headcount")
s3.assign_homework("sales engine")

students = [s1,s2,s3]

# YOUR CODE HERE
[s1.assignments, s2.assignments, s3.assignments].join(", ")

=> "linked list, sorting algos, write a c compiler, write a pacman game, headcount, sales engine"

What does the following code output?
=> x: 4
=> b: 12

def print_variables(x)
  puts "x: #{x}"
  puts "b: #{b}"
end

def b
  12
end

a = 4
print_variables(a)

Working with files: given a text file located at "~/Documents/pizza.txt", write code to read the file from the filesystem and print each line one at a time.

file = File.open("~/Documents/pizza.txt", "r") file.each{ |x| puts x }

Writing Files: given a text file located at "~/Documents/pizza.txt", write code to read the file from the filesystem, then write a new file at "~/Documents/line_count.txt" containing the number of lines in the original file.

file = File.open("~/Documents/pizza.txt", "r")
file.write("~/Documents/line_count.txt")file.each{ |x| x.length }

Imagine a simple ruby class designed to represent a Corgi dog. Write a test for each of the following features:

A Corgi can be created with no arguments
def test_no_arguments
  corgi = Corgi.new
  assert_equal nil, corgi.no_arg
end
A Corgi can be assigned a name
def test_it_has_a_name
  corgi = Corgi.new("Jojo")
  assert corgi.name
end
A Corgi can be asked for its name
def test_ask_name
  corgi = Corgi.new("Jojo")
  assert_equal name, corgi.ask_name
end
A Corgi can be asked for its posture, which should default to “standing”
def test_posture
corgi = Corgi.new
assert_equal "standing", corgi.posture
end
A Corgi can be asked to lie down, which should change its posture to “laying”
def test_laying
  corgi = Corgi.new
  assert_equal "laying", corgi.posture
end