Week 2 and 3 Diagnostic

week_2_and_3_diagnostic.md

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.

1. 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

2. Define a class called Student which is instantiated with a "name" value and which has a method name that returns this value

class Student
attr_reader :name

  def initialize(name)
    @name = name
  end
end

3. Given an array of the numbers [1,2,3,4,5], find the sum of the doubles of all the numbers

summed = given.map { |n| n * 2 }
summed.reduce(:+)

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

Pizza

5. 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_does_tasty_return_true
  taco_pizza = Pizza.new
  assert taco_pizza.tasty?
end

6. ?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_does_style_return_from_given_list
  fresh_pizza = Pizza.new
  assert_equal [some way to allow a range of choices], fresh_pizza.style
end

6. Give the Git commands needed to stage and then commit a set of changes to a file git add . git commit -m "commit message in present tense"

Student

7. 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_reader :attitude
  def initialize(attitude = "cheerful")
    @attitude = attitude
  end
end

8. Additionally, add an assign_homework method to Student. When assigned_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.

class Student
attr_reader :attitude
  def initialize(attitude = "cheerful")
    @attitude = attitude
  end
  
  def assign_homework
    if attitude == "cheerful"
      attitude = "dubious"
    elsif attitude == "dubious"
      attitude = "perturbed"
    elsif attitude == "perturbed"
      attitude = "dazed"
    else
      attitude = "dazed"
    end
  end
end

9. 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"

class Student
attr_reader :attitude, :task
  def initialize(attitude = "cheerful")
    @attitude = attitude
    @task = task
  end
  
  def assign_homework(task)
    task_list = []
    if attitude == "cheerful"
      attitude = "dubious"
      task_list << task
    elsif attitude == "dubious"
      attitude = "perturbed"
      task_list << task
    elsif attitude == "perturbed"
      attitude = "dazed"
      task_list << task
    else
      attitude = "dazed"
      task_list << task
    end
    task_list
  end

  def assignments
    task_list.join(", ")
  end
end

10. 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

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

MY CODE: puts students.assignments.flatten.join

11. What does the following code output?

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

def b
  12
end

a = 4
print_variables(a)

"x: 4"
"b: 12"

4 is passed to the print_variables argument, which then looks for b, first as a local variable and then as a sibling method. since b returns 12, it is passed as well.

12. ?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.open("~/Documents/pizza.txt", "r").readlines

13. ?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_to_work_with = File.open("~/Documents/pizza.txt", "r")
line_count = file_to_work_with.readlines
new_file = File.open("~/Documents/line_count.txt", "w").write(line_count)

14. 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
• A Corgi can be assigned a name
• A Corgi can be asked for its name
• A Corgi can be asked for its posture, which should default to "standing"
• A Corgi can be asked to lie down, which should change its posture to "laying"

def setup
  donald_the_corgi = Corgi.new
end

def test_can_corgi_be_created
  assert_instance_of Corgi, donald_the_corgi
end

def test_can_corgi_get_name
  assert_equal "Donald", donald_the_corgi.name
end

def test_can_corgi_be_questioned_about_name
  assert_equal "Donald", donald_the_corgi.ask_name
end

def test_can_corgi_be_questioned_about_posture
  assert_equal "standing", donald_the_corgi.ask_posture
end

def test_can_corgi_be_asked_to_lie_down
  assert_equal "laying", donald_the_corgi.lie_down
end