How to do proper database testing (TDD) on Rails 3 using MongoDB and Mongoid

Question

How would go about writing proper unit testing (and integration testing for that matter) using MongoDB through Mongoid on Rails ?

I am asking, because to the opposite of using let's say SQLite3, even when running tests, everything I do does persists. So for the moment I am writing the creation test and then I manually delete everything I do. But it's getting annoying and even complicated to do for integration testing.

Sample of what I do:

before(:each) do
  @user = User.create!(@attr)
end

after(:each) do
  # MongoDB is not a transactional DB, so added objects (create) during tests can't be rollbacked
  # checking for the existance of a similar object with exact :name and :email (regex make it case insensitive)
  cleanup = User.where(:name => "Example User", :email => /^user@example.com/i)
  cleanup.destroy unless cleanup.nil?
end

Any idea how to make MongoDB not persistent during Testing ? (I can't even run the console in sandbox mode because to use Mongoid I had to deactivate Active Record).

score 12 · Answer 1 · edited Feb 13 '13 at 17:03

12

Ok thanks to Kyle who pointed me in the right direction, I found out how to make it work.

So basically the trick is to drop all your collections in mongodb for each test case that you will run. This is a bit radical, but it works. But keep in mind that you won't retain any data at all in you test db.

Finally I found that link: http://adventuresincoding.com/2010/07/how-to-configure-cucumber-and-rspec-to-work-with-mongoid

And basically what you need to do is simple:

add a block in you spec_helper.rb:

RSpec.configure do |config|

# blabla other confs

  config.before :each do
    Mongoid.master.collections.select {|c| c.name !~ /system/ }.each(&:drop)
  end

# blabla other confs

end

For Mongoid 3:

 Mongoid.default_session.collections.select {|c| c.name !~ /system/ }.each(&:drop

This effectively kills all the collection within the db allowing you to run your tests fresh every time.

Alex

edited Feb 13 '13 at 17:03

Adrian

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answered Jan 15 '11 at 10:12

Alex

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The mongoid documentation covers this as well. You can also use the database_cleaner gem http://mongoid.org/docs/integration/ – Christos Jan 19 '11 at 00:19
Thank you. This is so much nicer than having to worry about a gem specifically for cleaning the database haha. – Batkins Oct 25 '11 at 23:14
@Christos, the link your mentioned is broken. – Siwei May 22 '12 at 03:31
4

Note that if you're using **Mongoid 3**, you will need something like: `Mongoid.default_session.collections.select {|c| c.name !~ /system/ }.each(&:drop)` – Alessandro Aug 03 '12 at 10:15
isn't there a convenient way to automaticaly call the "rake db:drop"? – Lucas Pottersky Jan 30 '13 at 18:15
For Mongoid >= 6: ```Mongoid.default_client.collections.select {|c| c.name !~ /system/ }.each(&:drop)``` – ypicard Jan 16 '19 at 03:30

score 5 · Answer 2 · answered Aug 24 '12 at 22:55

Another way is to use database_cleaner. It supports multiple ORMs, so I think you could do something like this:

# spec/support/database_cleaner.rb
RSpec.configure do |config|
  config.before(:suite) do
    DatabaseCleaner[:mongoid].strategy = :truncation
    DatabaseCleaner[:mongoid].clean_with(:truncation)
  end

  config.before(:each) do
    DatabaseCleaner.start
  end

  config.after(:each) do
    DatabaseCleaner.clean
  end
end

score 4 · Accepted Answer · answered Jan 14 '11 at 15:12

4

There's no way to make MongoDB non-persistent. You simply have to delete data before or after each test. There's some documentation on that here:

http://www.mongodb.org/display/DOCS/Rails+-+Getting+Started#Rails-GettingStarted-Testing

answered Jan 14 '11 at 15:12

Kyle Banker

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Thanks, that's what I was afraid of... Good link though, I thought I have read through the complete mongoDB pages, but not yet apparently :) I'll try that solution to avoid having to add manual code every time I am writing test. – Alex Jan 15 '11 at 05:25

score 2 · Answer 4 · answered Jan 30 '13 at 18:29

2

Here's what I did (using Test::Unit and Mongoid 3)...

# test/test_helper.rb
setup {
  Mongoid.default_session.collections.select {|c| c.name !~ /system/ }.each(&:drop)
}

answered Jan 30 '13 at 18:29

Lucas Pottersky

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score 2 · Answer 5 · answered Jul 10 '15 at 02:34

2

This one worked for me.

In spec_helper.rb, under RSpec.configure do |config| I put:

config.before :each do
   Mongoid.purge!
end

Reference.

answered Jul 10 '15 at 02:34

Askar

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How to do proper database testing (TDD) on Rails 3 using MongoDB and Mongoid

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