example.rb

module MyModule
  SUBTESTS = %w[foo bar baz]
end

describe "#add_question_set_of_type" do
  MyModule::SUBTESTS.each do |subtest|
    describe %Q("#{subtest}") do
      let(:subtest) { "#{subtest} in let" }
      before { @subtest = "#{subtest} in before" }
      it "does something" do
        p subtest
        p @subtest
      end
    end
  end
end

rspec-1-output.txt

$ spec example_spec.rb 
"foo"
"foo in before"
."bar"
"bar in before"
."baz"
"baz in before"
.

Finished in 0.007255 seconds

3 examples, 0 failures

rspec-2-output.txt

$ rspec example_spec.rb 
"foo"
"foo in before"
."bar"
"bar in before"
."baz"
"baz in before"
.

Finished in 0.00126 seconds
3 examples, 0 failures