Create #mock_expects that goes directly to RSpec Mocks.

Gemfile

@@ -22,7 +22,7 @@ gem 'mime-types', '~> 1.5'
 gem 'jekyll_test_plugin'
 gem 'jekyll_test_plugin_malicious'
 gem 'liquid-c', '~> 3.0'
-gem 'minitest', '5.5.1'
+gem 'minitest'
 gem 'minitest-reporters'
 gem 'minitest-profile'
 gem 'test-unit' if RUBY_PLATFORM =~ /cygwin/ || RUBY_VERSION.start_with?("2.2")

test/helper.rb

@@ -32,6 +32,11 @@ Minitest::Reporters.use! [Minitest::Reporters::DefaultReporter.new(:color => tru
 class JekyllUnitTest < Minitest::Test
   include ::RSpec::Mocks::ExampleMethods
 
+  def mocks_expect(*args)
+    RSpec::Mocks::ExampleMethods::ExpectHost.instance_method(:expect).\
+      bind(self).call(*args)
+  end
+
   def before_setup
     ::RSpec::Mocks.setup
     super

test/test_command.rb

@@ -4,10 +4,11 @@ class TestCommand < JekyllUnitTest
   context "when calling .add_build_options" do
     should "add common options" do
       cmd = Object.new
-      expect(cmd).to receive(:option).at_least(:once)
+      mocks_expect(cmd).to receive(:option).at_least(:once)
       Command.add_build_options(cmd)
     end
   end
+
   context "when calling .process_site" do
     context "when fatal error occurs" do
       should "exit with non-zero error code" do