rails/rails — pull request #9689 by michald (2013-03-12 20:28:12+00:00)
Title: Added possibility to pass a hash to assert_difference.

As in the topic. Instead of this:

```
assert_difference 'Article.count' do
assert_difference 'Post.count', 2 do
...
end
end
```

we can use:

```
assert_difference 'Article.count' => 1, 'Post.count' => 2 do
...
```