BLOC Blocks

Blocks

#CP1

def sort_by_length(sort_this_array)
  sort_this_array.sort { |x,y| x.length <=> y.length}
end

def filter(filter_this_array)
  filter_this_array.select { |num| num > 5 }
end

#RSpec

describe "sort_by_length" do
  it "sorts an array of strings by length" do
    a = %w(z yyyy xxx ww)
    sorted = %w(z ww xxx yyyy)
    sort_by_length(a).should eq(sorted)
  end
  it "sorts hashes by length" do
    a = [{a: "a", b: "b"}, { key: "value"}, {}]
    sorted = [{}, { key: "value"}, {a: "a", b: "b"}]
    sort_by_length(a).should eq(sorted)
  end
end

describe "filter" do
  it "returns numbers greater than 5 in a small array" do
    filter([1, 3, 7, 8]).should eq([7, 8])
  end
  it "returns numbers greater than 5 in a large array" do
    a = [1, 2, 17, 56, 7, 12, 3, 18, 19, 23]
    r = [17, 56, 7, 12, 18, 19, 23]
    filter(a).should eq(r)
  end
end

#CP2
def add_two(map_this_array)
  map_this_array.map { |item| "#{item} + 2 = #{item + 2}" }
end

#RSpec
describe "add_two" do
  it "adds 2 to each element in an array" do
    a = [1, 2, 3]
    r = ["1 + 2 = 3", "2 + 2 = 4", "3 + 2 = 5"]
    add_two(a).should eq(r)
  end
  it "adds 2 to each element in a longer array" do
    a = [5, 7, 3, 12, 15]
    r = ["5 + 2 = 7", 
         "7 + 2 = 9", 
         "3 + 2 = 5", 
         "12 + 2 = 14", 
         "15 + 2 = 17"]
    add_two(a).should eq(r)
  end
end

#CP3

class Array
  def new_map
    a = []
    self.each do |item|
      a << yield(item)
  end
    a 
  end

  def new_map!(&block)
    replace_array = self
    replace_array.replace(self.new_map(&block))
  end
end


#RSpec
describe "Array" do
  describe "new_map" do
    it "should not call map" do
      a = [1, 2, 3]
      a.stub(:map) { '' }

      a.new_map { |i| i + 1 }.should eq([2, 3, 4])
    end
    it "should map any object" do
      a = [1, "two", :three]
      a.new_map { |i| i.class }.should eq([Fixnum, String, Symbol])
    end
  end

  describe "new_map!" do
    it "should change the array" do
      a = [1, 2, 3]
      a.new_map! { |i| i + 1 }
      a.should eq([2, 3, 4])
    end
    it "should change the array for classes" do
      a = [1, "two", :three]
      a.new_map! { |i| i.class }
      a.should eq([Fixnum, String, Symbol])
    end
  end
end