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Project: RSpec Rails 2-14

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When you run rails generate rspec:install, the spec/spec_helper.rb file
includes the following configuration:

RSpec.configure do |config|
  config.use_transactional_fixtures = true
end

The name of this setting is a bit misleading. What it really means in Rails
is "run every test method within a transaction." In the context of rspec-rails,
it means "run every example within a transaction."

The idea is to start each example with a clean database, create whatever data
is necessary for that example, and then remove that data by simply rolling back
the transaction at the end of the example.

Disabling transactions

If you prefer to manage the data yourself, or using another tool like
database_cleaner to do it for you,
simply tell RSpec to tell Rails not to manage transactions:

RSpec.configure do |config|
  config.use_transactional_fixtures = false
end

Data created in before(:each) are rolled back

Any data you create in a before(:each) hook will be rolled back at the end of
the example. This is a good thing because it means that each example is
isolated from state that would otherwise be left around by the examples that
already ran. For example:

describe Widget do
  before(:each) do
    @widget = Widget.create
  end

  it "does something" do
    expect(@widget).to do_something
  end

  it "does something else" do
    expect(@widget).to do_something_else
  end
end

The @widget is recreated in each of the two examples above, so each example
has a different object, and the underlying data is rolled back so the data
backing the @widget in each example is new.

Data created in before(:all) are not rolled back

before(:all) hooks are invoked before the transaction is opened. You can use
this to speed things up by creating data once before any example in a group is
run, however, this introduces a number of complications and you should only do
this if you have a firm grasp of the implications. Here are a couple of
guidelines:

  1. Be sure to clean up any data in an after(:all) hook:

    before(:all) do
      @widget = Widget.create!
    end
    
    after(:all) do
      @widget.destroy
    end
    

    If you don't do that, you'll leave data lying around that will eventually
    interfere with other examples.

  2. Reload the object in a before(:each) hook.

    before(:all) do
      @widget = Widget.create!
    end
    
    before(:each) do
      @widget.reload
    end
    

    Even though database updates in each example will be rolled back, the
    object won't know about those rollbacks so the object and its backing
    data can easily get out of sync.


Last published about 1 month ago by alindeman.