Testing Hash[] instead of #dup

gistfile1.txt

require 'benchmark/ips'

def quux(hash_arg)
 hash_arg = hash_arg.dup
 10.times { |i| hash_arg.merge!({ "num_#{i}" => i }) }
end

def corge(hash_arg)
 hash_arg = Hash[hash_arg]
 10.times { |i| hash_arg.merge!({ "num_#{i}" => i }) }
end

Benchmark.ips do |x|
  x.report("merge! with dup") { quux({}) }
  x.report("merge! with Hash[]") { corge({}) }
  x.compare!
end

results

Calculating -------------------------------------
     merge! with dup     4.759k i/100ms
  merge! with Hash[]     4.863k i/100ms
-------------------------------------------------
     merge! with dup     52.455k (± 3.7%) i/s -    266.504k
  merge! with Hash[]     53.576k (± 3.7%) i/s -    267.465k

Comparison:
  merge! with Hash[]:    53575.8 i/s
     merge! with dup:    52454.7 i/s - 1.02x slower