An RSpec matcher for asserting AR query

query_matcher.rb

RSpec::Matchers.define :query do |query_hash|
  match do |relation|
    @failed = []

    query_hash[:where].each do |k, v|
      @failed << :where if relation.where_values_hash[k] != v
    end if query_hash.has_key? :where

    if query_hash.has_key? :order
      @failed << :order unless query_hash[:order].in? relation.order_values
    end

    if query_hash.has_key? :limit
      @failed << :limit unless query_hash[:limit] == relation.limit_value
    end

    if query_hash.has_key? :offset
      @failed << :offset unless query_hash[:offset] == relation.offset_value
    end

    @failed.none?
  end

  failure_message_for_should do |model|
    "expected #{@failed.inspect} to query #{query_hash.inspect}"
  end
end

user_spec.rb

require 'spec_helper'

describe User do
  subject { User.where(:name => 'foo').where('age > 20').order('created_at desc').order('id desc').limit(10).offset(30) }
  it { should query :where => {:name => 'foo'} }
  it { should query :where => {:name => 'bar'} }
  it { should query :order => 'id desc' }
  it { should query :limit => 30 }
  it { should query :offset => 30 }
end

Xresult

% rspec spec/models/user_spec.rb
.F.F.

Failures:

  1) User 
     Failure/Error: it { should query :where => {:name => 'bar'} }
       expected [:where] to query {:where=>{:name=>"bar"}}
     # ./spec/models/user_spec.rb:6

  2) User 
     Failure/Error: it { should query :limit => 30 }
       expected [:limit] to query {:limit=>30}
     # ./spec/models/user_spec.rb:8

Finished in 0.01415 seconds
5 examples, 2 failures