about_sandwich.rb

# -----------------------------------------------------
#          example_file.txt
# -----------------------------------------------------

this
is
a
test

# -----------------------------------------------------
#          about_sandwich_code.rb
# -----------------------------------------------------

def find_line2(file_name)
           lines = []
           File.open(file_name) do |file|
                   while each_line = file.gets
                           lines << each_line
                   end
           end
           lines[2]

end

def test_finding_lines2
     assert_equal "is\n", find_line2("example_file.txt")
  end

# -----------------------------------------------------
#               The error
# -----------------------------------------------------

undefined local variable or method `lines' for #<AboutSandwichCode:0x7f47741c6ac0>