ScopeChain

ScopeChain is a tiny helper class useful for testing ActiveRecord model scope usage and scope chaining

Usage

For example, say you have:

class User < ActiveRecord::Base
end

And you use that model:

def some_method
  User.where(active: 1).order("created_at desc")
end

And you want to test that method, but without creating data in your database, or actually using the data base.

Using ScopeChain, you do:

context "my method" do
  it "gets the right users" do
    ScopeChain.for(User).where(active: 1).order("created_at desc")
    some_method
  end
end

What this will do is setup some expectations that make sure those scope methods are called.

You can do "manual" scopes:

def manual_scopes
  User.scoped.where("something = else")
end

it "does the right thing" do
  ScopeChain.for(User).where("something = else")
  manual_scopes
end

You can test return values:

def return_values
  User.where("thing = 1")
end

it "returns properly" do
  ScopeChain.for(User).where("thing = 1").returns(5)

  return_values.should eq(5)
end

You can test associations on individual model instances:

class Model < ActiveRecord::Base
end

class Owner < ActiveRecord::Base
  has_many :models

  def my_method
    models.create(column: 5)
  end
end

def test_my_method
  owner = Owner.new
  ScopeChain.on(owner).as(:models).create(column: 5)

  owner.my_method
end

You can test named scopes (for execution, not for what they do):

class Model < ActiveRecord::Base
  scope :active, where("1 = 1")

  def self.my_method
    active.order("id")
end

it "should be ordered" do
  ScopeChain.for(Model).active.order("id").returns("abc")

  Model.active.should eq("abc")
end

Note that the named scope support does dirty things to the ActiveRecord namespace, which means you really should have "require: false" in your Gemfile.

Like, for reals.

Known Issues

Uh, actual, user defined scopes don't work. Or if they do, I'd be surprised. And I'm sure I'm missing a bunch of the ActiveRecord methods that are used.

Installation

Add this line to your application's Gemfile:

gem 'scope_chain'

And then execute:

$ bundle

Or install it yourself as:

$ gem install scope_chain

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request