group :test do
  # For RSpec
  gem "parameterized_testing-rspec", "~> 0.2"

  # For minitest/spec
  gem "parameterized_testing-minitest-spec", "~> 0.2"
end

# parameterized_testing-rspec example
RSpec.describe "something" do
  # #parameterized is available in the context of RSpec ExampleGroup.
  parameterized(:a, :b, :result) do
    # Declare the concrete input corresponding to the parameters with #input.
    input { [1, 2, 3] }                  # shorthand syntax
    input { { a: 4, b: 5, result: 9 } }  # verbose syntax
    input { ["foo", "bar", "foobar"] }
    ...

    # Other than that, we can write tests in the same way as a conventional RSpec ExampleGroup.
    subject { a + b }

    it { is_expected.to eq result }
  end
end

RSpec.describe "something" do
  sig_a_b_result = ::ParameterizedTesting::Signature.new(:a, :b, :result)

  context 'input[0] at line 6' do
    let(:_input_a_b_result) { sig_a_b_result.map([1, 2, 3]) }
    let(:a) { __send__(:_input_a_b_result).fetch(:a) }
    let(:b) { __send__(:_input_a_b_result).fetch(:b) }
    let(:result) { __send__(:_input_a_b_result).fetch(:result) }

    subject { a + b }

    it { is_expected.to eq result }
  end

  context 'input[1] at line 7' do
    let(:_input_a_b_result) { sig_a_b_result.map({ a: 4, b: 5, result: 9 }) }
    ...
  end

  context 'input[2] at line 8' do
    let(:_input_a_b_result) { sig_a_b_result.map(["foo", "bar", "foobar"]) }
    ...
  end

  ...
end

describe "something" do
  parameterized(:op, :result) do
    input { [->(x, y) { x + y }, a + b] }
    input { [->(x, y) { x * y }, a * b] }

    subject { op.call(a, b) }

    parameterized(:a, :b) do
      input { [2, 3] }
      input { [5, 7] }

      it "tests something" do
        _(subject).must_equal result
      end
    end
  end
end