Ruby on Rails Online Test

Implement the function find_roots to find the roots of the quadratic equation: ax² + bx + c = 0. The function should return an array containing both roots in any order. If the equation has only one solution, the function should return that solution as both elements of the array. The equation will always have at least one solution.

The roots of the quadratic equation can be found with the following formula:

For example, find_roots(2, 10, 8) should return [-1, -4] or [-4, -1] as the roots of the equation 2x² + 10x + 8 = 0 are -1 and -4.

Select all statements that are correct after the following migration has been executed:

class ContactsMigration < ActiveRecord::Migration
  def change
    create_table :contacts do |t|
      t.string :name
      t.integer :telephone_number
      t.text :address, null: false
      t.timestamps
    end
  end
end

As part of a data processing pipeline, complete the implementation of the pipeline method:

• The pipeline method should accept a variable number of functions, and it should return a new function that accepts one parameter arg.
• The returned function should call the first function in pipeline with the parameter arg, and call the second function with the result of the first function.
• The returned function should continue calling each function in pipeline in order, following the same pattern, and return the value from the last function.

For example, calling pipeline(-> (x) { x * 3 }, -> (x) { x + 1 }, -> (x) { x / 2 }), and then calling the returned function with 3 should return 5.

Implement the filter method. It should accept a list of students and a variable number of filters. The filters will be passed in as lambdas, each of which will take one student record and return a boolean value.

filter should return a list of student records that have passed through all the filters.

If no filters are provided, the list of student records should be returned as is. If no students pass through all the provided filters (or if no students are provided), return an empty array.

For example, consider the following code:

students = [
  { name: 'Thomas Edison', gpa: 3.45 },
  { name: 'Grace Hopper', gpa: 3.99 },
  { name: 'Leonardo DaVinci', gpa: 2.78 }
]

honor_roll = ->(record) { record[:gpa] > 3.0 }

filter(students, honor_roll) should return:

[{:name=>"Thomas Edison", :gpa=>3.45},{:name=>"Grace Hopper", :gpa=>3.99}]

Implement the unique_names method. When passed two arrays of names, it will return an array containing the names that appear in either or both arrays. The returned array should have no duplicates.

For example, calling unique_names(["Ava", "Emma", "Olivia"], ["Olivia", "Sophia", "Emma"]) should return an array containing Ava, Emma, Olivia, and Sophia in any order.

Implement a group_by_owners function that:

• Accepts a hash containing the file owner name for each file name.
• Returns a hash containing an array of file names for each owner name, in any order.

For example, for hash {'Input.txt' => 'Randy', 'Code.py' => 'Stan', 'Output.txt' => 'Randy'} the group_by_owners function should return {'Randy' => ['Input.txt', 'Output.txt'], 'Stan' => ['Code.py']}.

Consider the following controller and view definitions:

class RecordsController < ApplicationController
  def update
    @record = Record.find(params[:id])
    @record.update(record_params)
  end
end

<%= form_for @record do |f| %>
<%= render 'form', f: f %>
<% end %>

Select the statements that can be used to update a record.

A company database contains the following table, in which id is the primary key:

employees

Select all the statements that return only the employee with name "John" (id = 2).