Test that exception is thrown in Rails < 3.1

AbstractAdapter doesn't provide the required payload information until
3.1. Raising of the exception was moved out of the filter_query method
because the exception was being thrown during evaluation of the
subscribe block which prevented the eventual call to unsubscribe and
potentially failing other unrelated specs.

lib/shoulda/matchers/active_record/query_the_database_matcher.rb

@@ -44,6 +44,8 @@ module Shoulda # :nodoc:
         end
 
         def matches?(subject)
+          raise "Rails 3.1 or greater is required" unless rails_3_1?
+
           @queries = []
 
           subscriber = ActiveSupport::Notifications.subscribe('sql.active_record') do |name, started, finished, id, payload|
@@ -88,7 +90,6 @@ module Shoulda # :nodoc:
         end
 
         def filter_query(query_name)
-          raise "Rails 3.1 or greater is required" unless rails_3_1?
           query_name == 'SCHEMA'
         end
 

spec/shoulda/active_record/query_the_database_matcher_spec.rb

@@ -49,6 +49,14 @@ describe Shoulda::Matchers::ActiveRecord::QueryTheDatabaseMatcher do
       model.should_not query_the_database.when_calling(:count).with("arguments")
     end
 
+  else
+
+    it "should raise an exception on Rails < 3.1" do
+      lambda {
+        @parent.should query_the_database(1.times).when_calling(:count)
+      }.should raise_exception
+    end
+
   end
 
 end