Minitest

assert_style.rb

require 'test_helper'

class FizzBuzzTest < Minitest::Test
  def setup
    @fb ||= FizzBuzz.new
  end

  def test_converts_multiples_of_fifteen_to_fizzbuzz
    assert_equal 'Buzz', @fb.convert(5)
  end

  def test_converts_multiples_of_five_to_buzz
    assert_equal 'Buzz', @fb.convert(3)
  end
  
  def teardown
  end
end

rails_style.rb

require 'test_helper'

class ArticleTest < ActiveSupport::TestCase
  test "should not save article without title" do
    article = Article.new
    assert_not article.save
  end
end

spec_style.rb

require 'test_helper'

describe "Lebowski", "new syntax" do
  let(:the_dude)  { Lebowski.new(name: "Jeffrey") }

  it "should abide" do
    _(the_dude).must :abide?
    expect(the_dude).must :abide?
    value(the_dude).must :abide?
  end
end