Introduce mocha

Use [mocha][] for mocking and stubbing. Specifically, this will aid with
testing that we correctly install a gem with bundler in our generators.

[mocha]: https://github.com/freerange/mocha

Gemfile.lock

@@ -113,6 +113,8 @@ GEM
     marcel (1.0.2)
     mini_mime (1.1.5)
     minitest (5.20.0)
+    mocha (2.1.0)
+      ruby2_keywords (>= 0.0.5)
     mutex_m (0.1.2)
     net-imap (0.4.1)
       date
@@ -232,6 +234,7 @@ PLATFORMS
   x86_64-linux
 
 DEPENDENCIES
+  mocha
   puma
   sqlite3
   standard

suspenders.gemspec

@@ -27,5 +27,6 @@ Gem::Specification.new do |spec|
 
   spec.add_dependency "rails", Suspenders::RAILS_VERSION
 
+  spec.add_development_dependency "mocha"
   spec.add_development_dependency "standard"
 end

test/test_helper.rb

@@ -4,6 +4,7 @@
 require_relative "../test/dummy/config/environment"
 ActiveRecord::Migrator.migrations_paths = [File.expand_path("../test/dummy/db/migrate", __dir__)]
 require "rails/test_help"
+require "mocha/minitest"
 
 # Load fixtures from the engine
 if ActiveSupport::TestCase.respond_to?(:fixture_paths=)