I often see long before blocks with lots of should_receive ... and_return inside.

Remember that before blocks are about setting up the "stage" (the context of your test), not declaring your expectations!
Also, they get run for every spec (every it block).

So :

• convert your should_receives to stub calls in before blocks;
• have one or more it blocks with should_receive, if you actually care that the calls are made (watch out not to expect calls that are just an implementation details, only things that you need to see ca...

Regularly, but at least before merging your feature branches, rebase them to get rid of "fix typo" and "wip" commits.

Getting rid of unnecessary commits

Let's say you do a git rebase -i HEAD~~~~ and have this commit history:

pick 1d1e1f My Feature
pick 2d2e2f My Feature - wip
pick 3d3e3f My Feature - fix typo
pick 4d4e4f My Other feature

Change it to use fixup for those commits that should be merged into the one before ...

In a nutshell, use screen

Why?
Sometimes we are concerned that if our connection gets closed, the process we are running will close too.

The processes or login sessions you establish through screen don't go away. You can resume your screen sessions.

How?

1. run screen command
   screen
   or you can give that screen a name (will help afterwards)
   screen -S some_name

2. run your time consuming command
   script/runner path_to_some_long_script.rb

3. detatch from your screen with the following commands

• `Crt...

If you really, really have a good reason to write raw SQL (generally a bad practice), make sure you use the right call.

Avoid ActiveRecord::Base.connection.execute in general, in particular because Octopus relies on this to determine which queries go to replicas. execute would always go to the master.

A number of other methods are available: select_value, select_rows, of update being the most usual.

Wether you modify an existing named scope or add a new one, or when you write a new query, make sure you have the proper indices.

This particularly applies if you're going to run non-trivial queries of course (admin backends, analytics, etc).

Compound indices

A chain of scopes results in (usually) one query. You should take into account all attributes (columns) that are used in :conditions, :join, :group, :having, and :order, as all those result in filtering and sorting–slow operations without indices.

Take the list of all ...

As you know, time zones make stuff a bit more difficult but are necessary.

A time-zoned record is converted to UTC using to_s(:db) to be stored, and put back into the correct time zone when loaded. So when you are not on UTC, the following will happen:

>> Time.current
=> Fri, 15 Mar 2013 11:56:03 CET +01:00
>> Time.current.to_s(:db)
=> "2013-03-15 10:56:03" # This is now UTC

That will blow up in your face when you sen...

If you have a commit and you want to see in what branches is is included, you have to write this:

git branch -r --contains [COMMIT-SHA]

-r is for remote

Reading the current time

Don't use Time.now as it's broken when using time zones. \
Instead, use Time.current, DateTime.current or Date.current (the latter actually not being different, but just use it for good measure).

Parsing strings

Don't use Time.parse as it only gives you a Time object.
Use Time.zone.parse instead for a TimeWithZone.

Whenever you make a migration to add a foreign key, you should also add an index for it

  def self.up
    add_column :comments, :user_id, :integer
    add_index :comments, :user_id
  end

The request referrer is the URL you come from. It's set by the browser when you click a link (all browsers) and in Javascript click events too (all but the Internet Explorer family).

If you click a link on a page:

request.referer == request.referrer == request.env['HTTP_REFERER']

So far so good. But if you write the URL straight into the browser:

request.referer == request.env['HTTP_REFERER'] == nil

however

request.referrer == '/'

instead of nil.

This seems to happen in our current version of Rails, although not in Rails >= 3.x...

Gave a shot to the new Bundler 1.4.0RC1 during the weekend and found out it now supports gem installation in parallel. To invoke you need to pass --jobs parameter with number of threads you want it to run – for me the best performance was achieved by specifying the number physical CPU cores.

I've tested on the AppFab app. In my case (CPU with 2-core i7 with HT) the speedup was 50%. I've also tried with a number greater than the number of physical cores but the performance was 15%-20% worse.

Bundler 1.3...

File uploads with .png are +10 times slower than using .jpeg or .gif.

# Bad
post :create, {
  :property_id => property.id,
  :photo => {
    :image => File.open("#{Rails.root}/public/images/foo.png")
  }
}

# Good
post :create, {
  :property_id => property.id,
  :photo => {
    :image => File.open("#{Rails.root}/public/images/foo.jpeg")
  }
}

When using

var onDone = function() { ... }
var onFail = function() { ... }
var params = { ... }
var url = ...

$.ajax({
  type:  'put',
  url:  url,
  contentType: 'application/json; charset=utf-8',
  data:  JSON.stringify(params),
})
.done(onDone)
.fail(onFail);

Always make sure your rails controller returns something:

if @property.update_attributes(params[:property])
  render :json => { :ok => true }, :status => :ok
else
  render :json => { :ok => false }, :status => :unpro...

This happens when your machine does not have ghostscript installed, to fix it simply do

brew install ghostscript

This method won't throw an error:

def a_method
  raise
ensure
  return :something
end

it will in fact return :something

So please proceed with care :)

TL;DR: If using :group => :some_field you might want to :order => 'NULL'.

According to the man

By default, MySQL sorts all GROUP BY col1, col2, ... queries as if you specified ORDER BY col1, col2, ... in the query as well. If you include an ORDER BY clause explicitly that contains the same column list, MySQL optimizes it away without any speed penalty, although the sorting still occurs. If a query includes GROUP BY but you want to avoid the overhead of sorting ...

Given:

datetime = DateTime.now
date = datetime.to_date #or Date.today

will assert:

datetime.is_a? Date == true
datetime.is_a? DateTime == true
datetime.instance_of? Date == false
datetime.instance_of? DateTime == true

In case you have a table and a model like:

create_table :event do |t|
  t.date    :day
  t.string  :description
end
class Event < ActiveRecord::Base; end

And you say:

event = Event.new(:day => '2013-03-22')

Rails will convert the supplied value for day to the type of the database field,...

require 'ruby-prof' # you don't need this if you have ruby-prof in your Gemfile

You can set one of the things you want to measure by using (default is PROCESS_TIME most useful ones are PROCESS_TIME, MEMORY, CPU_TIME):
RubyProf.measure_mode = RubyProf::PROCESS_TIME
RubyProf.measure_mode = RubyProf::WALL_TIME
RubyProf.measure_mode = RubyProf::CPU_TIME
RubyProf.measure_mode = RubyProf::ALLOCATIONS
RubyProf.measure_mode = RubyProf::MEMORY
RubyProf.measure_mode = RubyProf::GC_RUNS
RubyProf.measure_mode = ...

What
The object returned by has_defaults apparently is the same between multiple object creations.
Consider this scenario:

class Order
  has_defaults :items => []
end

o1 = Order.new
o1.items #=>> []
o1.items << item
o1.items #=>> [item]

o2 = Order.new
o2.items #=>> [item]

So, now o2.items is not empty by default because we modified the same object in has_defaults

How
When using has_defaults on a model, consider using it in the following way:

has_defaults :items => proc {[] }

When
Consider do...

wkhtmltopdf hangs on mac during cucumber unless we click on it. The main reason is with the version we use which is 0.11.0_rc1 and in out app/bin we have another version and it is a known issue with these versions. The fix is to go to 0.9.9, to downgrade the version we installed earlier using brew:

* brew uninstall wkhtmltopdf
* brew update
* brew versions wkhtmltopdf
* if you see output like 
*         `0.9.9    git checkout 6e2d550 /usr/local/Library/Formula/wkhtmltopdf.rb`
           then `cd /usr/local`
* g...

1. Add to the end your .bash_profile export PATH="./vendor/bundle/bin:$PATH"
2. Also add alias bi="bundle install --path vendor/bundle --binstubs=vendor/bundle/bin"
3. Then to bundle install next time just use bi

Now no more bundle exec before any rake, cap, spec or anything else :)

When simply checking equality or truthiness then
Instead of:
it "should have role set to admin" do
@user.role.should eql('admin')
end

it "should be valid" do
  @user.valid?.should be_true
end

Do:
it { @user.role.should eql('admin') }
it { @user.valid?.should be_true}

Try to stick to one expectation per test block, diverge in exceptional circumstrances, so instead of:
describe "#some_method" do
before(:each) do
@object = Class.new
end

   it "should have attributes set" do

...

One of the main source of bugs and complexity in the code is when a functional method (that we expect to return a value) return different values under different circumstances.

For example, we ruby programmers have a bad habit of returning nil from a method when certain condition is not fulfilled else return an Array or Hash. That just makes the calling code unnecessary complex and error prone because then it has to do different checks.

Bad Practice:

def bad_method(param)
  return unless param == 'something'
  [1,2,3]
end

...

Do not use content_for inside a cached view fragment. It won't work because Memcache will just output whatever is in the cache, and not execute such commands.