Using Rails and Rspec, how do you test that the database is not touched by a method
- by Will Tomlins
So I'm writing a test for a method which for performance reasons should achieve what it needs to achieve without using SQL queries. I'm thinking all I need to know is what to stub:
describe SomeModel do
describe 'a_getter_method' do
it 'should not touch the database' do
thing = SomeModel.create
something_inside_rails.should_not_receive(:a_method_querying_the_database)
thing.a_getter_method
end
end
end
EDIT: to provide a more specific example:
class Publication << ActiveRecord::Base
end
class Book << Publication
end
class Magazine << Publication
end
class Student << ActiveRecord::Base
has_many :publications
def publications_of_type(type)
#this is the method I am trying to test.
#The test should show that when I do the following, the database is queried.
self.publications.find_all_by_type(type)
end
end
describe Student do
describe "publications_of_type" do
it 'should not touch the database' do
Student.create()
student = Student.first(:include => :publications)
#the publications relationship is already loaded, so no need to touch the DB
lambda {
student.publications_of_type(:magazine)
}.should_not touch_the_database
end
end
end
So the test should fail in this example, because the rails 'find_all_by' method relies on SQL.
