空のプロジェクトで、Rspecをセットアップする

gistfile1.sh

$ mkdir new_project & cd new_project
$ bundle init
#=> Gemfileのひな形が生成される

$ vim Gemfile
#=> gem "rspec" を追加する

$ bundle install --path vendor/bundle

$ bundle exec rspec --init
  create   spec/spec_helper.rb
  create   .rspec

$ tree .
.
├── Gemfile
├── Gemfile.lock
├── spec
│   └── spec_helper.rb
└── vendor

# ひな形ができたのでコードを書き始める
# 例えば...
$ mkdir lib
$ touch lib/hoge.rb

$ mkdir spec/lib
$ touch spec/lib/hoge_spec.rb

$ bundle exec rspec spec

hoge.rb

class Hoge
  def fuga
    'hahaha'
  end
end

hoge_spec.rb

require 'spec_helper'

describe Hoge do
  describe "#fuga" do
    it "returns 'hahaha'" do
      expect(hoge.fuga).to eq("hahaha")
    end
  end
end

spec_helper.rb

require 'rubygems'
require File.expand_path(File.join(File.dirname(__FILE__), '..', 'lib', 'hoge'))

# 以下は rspec --init で生成されるので、使うかどうかは好みでOKです。

# This file was generated by the `rspec --init` command. Conventionally, all
# specs live under a `spec` directory, which RSpec adds to the `$LOAD_PATH`.
# Require this file using `require "spec_helper"` to ensure that it is only
# loaded once.
#
# See http://rubydoc.info/gems/rspec-core/RSpec/Core/Configuration
RSpec.configure do |config|
  config.treat_symbols_as_metadata_keys_with_true_values = true
  config.run_all_when_everything_filtered = true
  config.filter_run :focus

  # Run specs in random order to surface order dependencies. If you find an
  # order dependency and want to debug it, you can fix the order by providing
  # the seed, which is printed after each run.
  #     --seed 1234
  config.order = 'random'
end