# assert_difference

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A nice assert_difference method similar to the one provided by Rails but with some improvements. For example:

    assert_difference "Company.count" => +1, "User.count" => +5, "Slot.count" => -1 do
      post :something
    end

will assert that a company and 5 users were create (the plus sign is only for the visual aid) and a slot was removed.

[Rails' assert_difference](http://api.rubyonrails.org/classes/ActiveSupport/Testing/Assertions.html#method-i-assert_difference)
would require a more verbose syntax:

    assert_difference "Company.count" do
      assert_difference "User.count", +5 do
        assert_difference "Article.count", -1 do
          post :something
        end
      end
    end

Expectations can also be ranges, for example:

    assert_difference "Blog.count" => +1, "Post.count" => 2..5 do # Generate some sample posts when creating a blog
      post :create
    end

On top of that, error reporting is improved by displaying all the counters that didn't match.

To use it with Test::Unit add this code:

    class Test::Unit::TestCase
      include AssertDifference
    end

or in Rails:

    class ActiveSupport::TestCase
      # ...
      include AssertDifference
    end

and to use it with RSpec:

    RSpec.configure do |config|
      config.include AssertDifference
    end

This gem should work without Rails but it does depend on active support >= 3.0.0 and it's [tested with active support 3.0, 3.1, 3.2, 4.0 and 4.1 as well as Ruby 1.9.3, 2.0 and 2.1](https://travis-ci.org/pupeno/assert_difference).

## Users

This gem is being used by:

- [Watu](https://watuapp.com)
- You? please, let us know if you are using this gem.

## Changelog

### Next version
- Modernization of the gem.
- Test with 100% code coverage.
- Started using Travis-CI for continuous testing.
- Started testing in various versions of active support and ruby.
- Improved documentation.

### Version 0.5.0 (Aug 6, 2012)
- Expectations can be ranges.

### Version 0.4.2 (Aug 6, 2012)
- Fixed important typo.

### Version 0.4.1 (Aug 6, 2012)
- Better error reporting (all unmatching counters).

### Version 0.4.0 (Feb 21, 2012)
- Fix crash on missing gems.
- Return what the blocks returns.

### Version 0.3.1 (Aug 25, 2011)
- Fixed documentation.

### Version 0.3.0 (Aug 24, 2011)
- Better organization of code with modules.
- Switched to bundler from jeweler.
- Removed unneeded dependencies.
- Cleaned up documentation.

### Version 0.1.0 (Oct 2, 2010)
- Initial release. Code extracted from a personal project.

## 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


Copyright
---------

Copyright (c) 2010, 2011, 2012, 2014 José Pablo Fernández. See LICENSE for details.