acronymize.rb

def acronymize(text)
  # 'text' is a string
  # we need access to each word (so lets break it up) => array
  words = text.split # we have an array now 👍
  # get the first letter of each --> join them --> capitalize the whole word
  words.map{|word| word[0]}.join.upcase
end

# 'situation normal all fucked up' => snafu
p acronymize('situation normal all fucked up')

acronymize_spec.rb

# spec/acronymize_spec.rb
# the naming convention if this file is important, as we know it relates to our acronymize.rb file

# To use our encrypt method, let's import the file using 'require_relative'...
# (this allows us to specify our path relative to this current file)
require_relative "../acronymize"

describe "#acronymize" do
  it "returns an empty string when passed an empty string" do
    actual = acronymize("")
    expected = ""
    expect(actual).to eq(expected) # passes if `actual == expected`
  end

  it "returns the acronym on downcased sentences" do
    actual = acronymize("working from home")
    expected = "WFH"
    expect(actual).to eq(expected)
  end

  it "returns the acronym on upcased sentences" do
    actual = acronymize("AWAY FROM KEYBOARD")
    expected = "AFK"
    expect(actual).to eq(expected)
  end
end

encrypt.rb

# define our encrypt method
def encrypt(text)
  # 26 chars in the alphabet
  alphabet = ("A".."Z").to_a
  # get access to ech character of text
  array_of_chars = text.chars
  # loop through each character of our text (so that we can change it's value)
  array_of_chars.map do |char|
    index = alphabet.index(char)
    index ? alphabet[index - 3] : char
  end.join # and join all chars into single string
end

# quick test of the method
p encrypt("THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG")
# expected output => "QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD"

encrypt_spec.rb

# spec/encrypt_spec.rb
# the naming convention if this file is important, as we know it relates to our encrypt.rb file

# To use our encrypt method, let's import the file using 'require_relative'...
# (this allows us to specify our path relative to this current file)
require_relative "../encrypt"

# give our tests a name (almost like a section of tests)
describe "#encrypt" do
  # Let's start with the most basic test that we can pass
  it "returns an empty string when passed an empty string" do
    actual = encrypt("")
    expected = ""
    expect(actual).to eq(expected)
  end
  # Let's test to see if we get the desired result
  it "returns the 3-letter backward-shifted text" do
    actual = encrypt("THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG")
    expected = "QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD"
    expect(actual).to eq(expected)
  end
end