Obsidian

DESCRIPTION

Obsidian. It's metastable.

In the tangible world, obsidian is a naturally-occurring glass that is metastable at the earth's surface. It's commonly found within the margins of rhyolitic lava flows, where cooling of the lava is rapid. [1] In the slightly less tangible world of programming, <b>Obsidian</b> is home to chunks of Ruby code that we've found helpful. These bits of code are often found at the bottom of a mountain of yak hair, the occasionally-occurring product of simplifying various tasks.

[1] http://en.wikipedia.org/wiki/Obsidian

FEATURES

Model Update Tracker

This library allows you to functionally test updates to models with clearer and more focused intent. It forces you to have a better understanding of how your objects interact and lets you demonstrate that knowledge by specifying it in your tests. For example, consider the following test which asserts that the code block persists an Asset record. 

assert_difference Asset :count do
  post :create, :asset => {}
end

Is it okay if the code block also persists a Location record? An AssetOwner record? Some other record? Chances are that the developer knows the answer to this question, but the test fails to capture that knowledge. Side effects matter, and our tests should adequately validate that the desired side effects (and <i>only</i> the desired side effects) are taking place. In the example below, assert_models_created allows us to validate that an Asset is created <i>and</i> that no other objects are inadvertently persisted. 

assert_models_created(Asset) do
  post :create, :asset => {}
end

If the code block happened to create records other than just an Asset, a friendly test failure would let you know right away.

Suppose, on the other hand, that you expect the creation of an Asset to <i>also</i> produce an AssetOwner and a Location. This is where you exercise your deep domain knowledge muscles and make your new Obsidian-powered test express and validate your intent. 

assert_models_created(Asset, AssetOwner, Location) do
  post: create, :asset => {}
end

Now, if your code block fails to create the expected records, the above test would fail stating that it expected more to happen. If future changes to your code cause things to fall out of place, this test will catch that regression where the original assert_difference may not. In addition to assert_models_created, Model Update Tracker provides a whole host of other methods that provide similar functionality for asserting behavior related to updates, deletes, or even validating that nothing happened.

  • assert_models_created(models)
  • assert_models_updated(models)
  • assert_models_destroyed(models)
  • assert_no_models_created
  • assert_no_models_destroyed
  • assert_no_models_updated

INSTALL

  sudo gem install obsidian

URLS