Instala o RSpec no app

Este commit inclui a gem `rspec-rails` no app. Com isto, podemos criar
testes utilizando o RSpec com comandos como, por exemplo:

$ rails generate rspec:model Book

Note que ao criar um model novo, você não precisa criar o teste de forma
separada. Por exemplo, o comando abaixo cria um model _e_ cria os testes
pra ele automaticamente:

$ rails generate model Book

Os passos de instalação do RSpec no projeto podem ser consultados com
mais detalhes no repositório da gem no GitHub: https://github.com/rspec/rspec-rails

Os passos, em resumo, são dois, na maior parte dos casos:
- Incluir a gem `rspec-rails` no seu Gemfile, como foi feito neste
commit
- Executar o comando `rails generate rspec:install`

.rspec

@@ -0,0 +1 @@
+--require spec_helper

Gemfile

@@ -30,6 +30,7 @@ gem 'bootsnap', '>= 1.1.0', require: false
 group :development, :test do
   # Call 'byebug' anywhere in the code to stop execution and get a debugger console
   gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
+  gem 'rspec-rails', '~> 3.9'
 end
 
 group :development do

Gemfile.lock

@@ -50,6 +50,7 @@ GEM
     byebug (11.1.1)
     concurrent-ruby (1.1.6)
     crass (1.0.6)
+    diff-lcs (1.3)
     erubi (1.9.0)
     ffi (1.12.2)
     globalid (0.4.2)
@@ -110,6 +111,23 @@ GEM
     rb-fsevent (0.10.3)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
+    rspec-core (3.9.1)
+      rspec-support (~> 3.9.1)
+    rspec-expectations (3.9.0)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.9.0)
+    rspec-mocks (3.9.1)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.9.0)
+    rspec-rails (3.9.0)
+      actionpack (>= 3.0)
+      activesupport (>= 3.0)
+      railties (>= 3.0)
+      rspec-core (~> 3.9.0)
+      rspec-expectations (~> 3.9.0)
+      rspec-mocks (~> 3.9.0)
+      rspec-support (~> 3.9.0)
+    rspec-support (3.9.2)
     ruby_dep (1.5.0)
     sass (3.7.4)
       sass-listen (~> 4.0.0)
@@ -158,6 +176,7 @@ DEPENDENCIES
   listen (>= 3.0.5, < 3.2)
   puma (~> 3.11)
   rails (~> 5.2.4, >= 5.2.4.1)
+  rspec-rails (~> 3.9)
   sass-rails (~> 5.0)
   spring
   spring-watcher-listen (~> 2.0.0)

spec/rails_helper.rb

@@ -0,0 +1,63 @@
+# This file is copied to spec/ when you run 'rails generate rspec:install'
+require 'spec_helper'
+ENV['RAILS_ENV'] ||= 'test'
+
+require File.expand_path('../config/environment', __dir__)
+
+# Prevent database truncation if the environment is production
+abort("The Rails environment is running in production mode!") if Rails.env.production?
+require 'rspec/rails'
+# Add additional requires below this line. Rails is not loaded until this point!
+
+# Requires supporting ruby files with custom matchers and macros, etc, in
+# spec/support/ and its subdirectories. Files matching `spec/**/*_spec.rb` are
+# run as spec files by default. This means that files in spec/support that end
+# in _spec.rb will both be required and run as specs, causing the specs to be
+# run twice. It is recommended that you do not name files matching this glob to
+# end with _spec.rb. You can configure this pattern with the --pattern
+# option on the command line or in ~/.rspec, .rspec or `.rspec-local`.
+#
+# The following line is provided for convenience purposes. It has the downside
+# of increasing the boot-up time by auto-requiring all files in the support
+# directory. Alternatively, in the individual `*_spec.rb` files, manually
+# require only the support files necessary.
+#
+# Dir[Rails.root.join('spec', 'support', '**', '*.rb')].each { |f| require f }
+
+# Checks for pending migrations and applies them before tests are run.
+# If you are not using ActiveRecord, you can remove these lines.
+begin
+  ActiveRecord::Migration.maintain_test_schema!
+rescue ActiveRecord::PendingMigrationError => e
+  puts e.to_s.strip
+  exit 1
+end
+RSpec.configure do |config|
+  # Remove this line if you're not using ActiveRecord or ActiveRecord fixtures
+  config.fixture_path = "#{::Rails.root}/spec/fixtures"
+
+  # If you're not using ActiveRecord, or you'd prefer not to run each of your
+  # examples within a transaction, remove the following line or assign false
+  # instead of true.
+  config.use_transactional_fixtures = true
+
+  # RSpec Rails can automatically mix in different behaviours to your tests
+  # based on their file location, for example enabling you to call `get` and
+  # `post` in specs under `spec/controllers`.
+  #
+  # You can disable this behaviour by removing the line below, and instead
+  # explicitly tag your specs with their type, e.g.:
+  #
+  #     RSpec.describe UsersController, :type => :controller do
+  #       # ...
+  #     end
+  #
+  # The different available types are documented in the features, such as in
+  # https://relishapp.com/rspec/rspec-rails/docs
+  config.infer_spec_type_from_file_location!
+
+  # Filter lines from Rails gems in backtraces.
+  config.filter_rails_from_backtrace!
+  # arbitrary gems may also be filtered via:
+  # config.filter_gems_from_backtrace("gem name")
+end

spec/spec_helper.rb

@@ -0,0 +1,96 @@
+# This file was generated by the `rails generate rspec:install` command. Conventionally, all
+# specs live under a `spec` directory, which RSpec adds to the `$LOAD_PATH`.
+# The generated `.rspec` file contains `--require spec_helper` which will cause
+# this file to always be loaded, without a need to explicitly require it in any
+# files.
+#
+# Given that it is always loaded, you are encouraged to keep this file as
+# light-weight as possible. Requiring heavyweight dependencies from this file
+# will add to the boot time of your test suite on EVERY test run, even for an
+# individual file that may not need all of that loaded. Instead, consider making
+# a separate helper file that requires the additional dependencies and performs
+# the additional setup, and require it from the spec files that actually need
+# it.
+#
+# See http://rubydoc.info/gems/rspec-core/RSpec/Core/Configuration
+RSpec.configure do |config|
+  # rspec-expectations config goes here. You can use an alternate
+  # assertion/expectation library such as wrong or the stdlib/minitest
+  # assertions if you prefer.
+  config.expect_with :rspec do |expectations|
+    # This option will default to `true` in RSpec 4. It makes the `description`
+    # and `failure_message` of custom matchers include text for helper methods
+    # defined using `chain`, e.g.:
+    #     be_bigger_than(2).and_smaller_than(4).description
+    #     # => "be bigger than 2 and smaller than 4"
+    # ...rather than:
+    #     # => "be bigger than 2"
+    expectations.include_chain_clauses_in_custom_matcher_descriptions = true
+  end
+
+  # rspec-mocks config goes here. You can use an alternate test double
+  # library (such as bogus or mocha) by changing the `mock_with` option here.
+  config.mock_with :rspec do |mocks|
+    # Prevents you from mocking or stubbing a method that does not exist on
+    # a real object. This is generally recommended, and will default to
+    # `true` in RSpec 4.
+    mocks.verify_partial_doubles = true
+  end
+
+  # This option will default to `:apply_to_host_groups` in RSpec 4 (and will
+  # have no way to turn it off -- the option exists only for backwards
+  # compatibility in RSpec 3). It causes shared context metadata to be
+  # inherited by the metadata hash of host groups and examples, rather than
+  # triggering implicit auto-inclusion in groups with matching metadata.
+  config.shared_context_metadata_behavior = :apply_to_host_groups
+
+# The settings below are suggested to provide a good initial experience
+# with RSpec, but feel free to customize to your heart's content.
+=begin
+  # This allows you to limit a spec run to individual examples or groups
+  # you care about by tagging them with `:focus` metadata. When nothing
+  # is tagged with `:focus`, all examples get run. RSpec also provides
+  # aliases for `it`, `describe`, and `context` that include `:focus`
+  # metadata: `fit`, `fdescribe` and `fcontext`, respectively.
+  config.filter_run_when_matching :focus
+
+  # Allows RSpec to persist some state between runs in order to support
+  # the `--only-failures` and `--next-failure` CLI options. We recommend
+  # you configure your source control system to ignore this file.
+  config.example_status_persistence_file_path = "spec/examples.txt"
+
+  # Limits the available syntax to the non-monkey patched syntax that is
+  # recommended. For more details, see:
+  #   - http://rspec.info/blog/2012/06/rspecs-new-expectation-syntax/
+  #   - http://www.teaisaweso.me/blog/2013/05/27/rspecs-new-message-expectation-syntax/
+  #   - http://rspec.info/blog/2014/05/notable-changes-in-rspec-3/#zero-monkey-patching-mode
+  config.disable_monkey_patching!
+
+  # Many RSpec users commonly either run the entire suite or an individual
+  # file, and it's useful to allow more verbose output when running an
+  # individual spec file.
+  if config.files_to_run.one?
+    # Use the documentation formatter for detailed output,
+    # unless a formatter has already been configured
+    # (e.g. via a command-line flag).
+    config.default_formatter = "doc"
+  end
+
+  # Print the 10 slowest examples and example groups at the
+  # end of the spec run, to help surface which specs are running
+  # particularly slow.
+  config.profile_examples = 10
+
+  # 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
+
+  # Seed global randomization in this process using the `--seed` CLI option.
+  # Setting this allows you to use `--seed` to deterministically reproduce
+  # test failures related to randomization by passing the same `--seed` value
+  # as the one that triggered the failure.
+  Kernel.srand config.seed
+=end
+end