array_wrapping.rb

require 'ostruct'
require 'benchmark'
# Make sure you `gem install benchmark-ips`
require 'benchmark/ips'

arrays = 100.times.collect {|i| (rand(10) + 1).times.collect { rand(100) } }
non_arrays = 100.times.collect do |i|
  case rand(3)
  when 0
    i + 1
  when 1
    "#{i + 1}"
  when 2
    i % 2 == 0
  end
end.shuffle
mixed = (arrays[0...50] + non_arrays[0...50]).shuffle

benchmark_lambda = lambda do |x|
  # Worst case - none need operation
  x.report("`Array()` arrays") do
    arrays.map {|i| Array(i) }
  end
  x.report("`[].flatten` arrays") do
    arrays.map {|i| [i].flatten }
  end
  x.report("`Array()` arrays with check") do
    arrays.map {|i| i.is_a?(Array) ? i : Array(i) }
  end
  x.report("`[]` arrays with check") do
    arrays.map {|i| i.is_a?(Array) ? i : [i] }
  end

  # Worst case - all need operation
  x.report("`Array()` non arrays") do
    non_arrays.map {|i| Array(i) }
  end
  x.report("`[].flatten` non arrays") do
    non_arrays.map {|i| [i].flatten }
  end
  x.report("`Array()` non arrays with check") do
    non_arrays.map {|i| i.is_a?(Array) ? i : Array(i) }
  end
  x.report("`[]` non arrays with check") do
    non_arrays.map {|i| i.is_a?(Array) ? i : [i] }
  end

  # Mixed case
  x.report("`Array()` mixed") do
    mixed.map {|i| Array(i) }
  end
  x.report("`[].flatten` mixed") do
    mixed.map {|i| [i].flatten }
  end
  x.report("`Array()` mixed with check") do
    mixed.map {|i| i.is_a?(Array) ? i : Array(i) }
  end
  x.report("`[]` mixed with check") do
    mixed.map {|i| i.is_a?(Array) ? i : [i] }
  end

  x.compare!
end

Benchmark.ips &benchmark_lambda