core: Add spec for running environment hooks with a custom Action::Runner

lib/vagrant/environment.rb

@@ -272,6 +272,7 @@ module Vagrant
     # against the given name will be run in the context of this environment.
     #
     # @param [Symbol] name Name of the hook.
+    # @param [Action::Runner] action_runner A custom action runner for running hooks.
     def hook(name, runner = action_runner)
       @logger.info("Running hook: #{name}")
       callable = Action::Builder.new

test/unit/vagrant/environment_test.rb

@@ -308,6 +308,14 @@ describe Vagrant::Environment do
 
       instance.hook(:bar).should == :foo
     end
+
+    it "should allow passing in a custom action runner" do
+      instance.action_runner.should_not_receive(:run)
+      other_runner = mock
+      other_runner.should_receive(:run).with(:bar).and_return(:foo)
+
+      instance.hook(:bar, other_runner).should == :foo
+    end
   end
 
   describe "primary machine name" do