Explicitly require used gems from spec_helpers

Previously we depended on a few gems which were only found via
Bundle.require

api/spec/spec_helper.rb

@@ -18,7 +18,13 @@
 require 'spree/testing_support/dummy_app'
 DummyApp::Migrations.auto_migrate
 
+require 'rails-controller-testing'
 require 'rspec/rails'
+require 'rspec-activemodel-mocks'
+
+require 'database_cleaner'
+require 'with_model'
+require 'timecop'
 
 # Requires supporting ruby files with custom matchers and macros, etc,
 # in spec/support/ and its subdirectories.

backend/spec/spec_helper.rb

@@ -21,6 +21,7 @@
 DummyApp::Migrations.auto_migrate
 
 require 'rails-controller-testing'
+require 'rspec-activemodel-mocks'
 require 'rspec/rails'
 
 # Requires supporting files with custom matchers and macros, etc,

core/spec/spec_helper.rb

@@ -12,6 +12,8 @@
  end
 end
 
+require 'rspec/core'
+
 require 'spree/testing_support/preferences'
 require 'spree/config'
 require 'with_model'

frontend/lib/generators/solidus/views/override_generator.rb

@@ -1,4 +1,5 @@
 require 'rails'
+require 'rails/generators'
 
 module Solidus
  module Views

frontend/spec/generators/solidus/views/override_generator_spec.rb

@@ -1,5 +1,6 @@
 require 'spec_helper'
-require_relative '../../../../lib/generators/solidus/views/override_generator'
+require 'generator_spec'
+require 'generators/solidus/views/override_generator'
 
 RSpec.describe Solidus::Views::OverrideGenerator, type: :generator do
  destination Rails.root.join('app', 'views', 'spree')

frontend/spec/spec_helper.rb

@@ -20,7 +20,9 @@
 require 'spree/testing_support/dummy_app'
 DummyApp::Migrations.auto_migrate
 
+require 'rails-controller-testing'
 require 'rspec/rails'
+require 'rspec-activemodel-mocks'
 
 # Requires supporting files with custom matchers and macros, etc,
 # in ./support/ and its subdirectories.

sample/spec/spec_helper.rb

@@ -8,6 +8,7 @@
 DummyApp::Migrations.auto_migrate
 
 require 'rspec/rails'
+require 'database_cleaner'
 
 RSpec.configure do |config|
  config.color = true