Thursday, November 18, 2010

RSpec 2: #raise_error

I was writing a spec and attempted to use #raise_error. To my surprise, it wasn't working. Here's what I did and how I solved it.

Code to be tested:
class TestClass
  def run; raise "Error"; end

it 'should raise' do raise_error

To my surprise, the error wasn't caught and it failed with a raised error. There was no syntax error and the way I wrote it felt very natural, but it wasn't behaving the way I thought it should. However, upon further investigation, I realized the usage of #raise_error is on a Proc or lambda.

The spec should have been:
it 'should raise' do { }.should raise_error
  lambda { }.should raise_error

And if you really want it to read well:
it 'should raise' do
  expect { }.to raise_error

Thursday, November 11, 2010

Fixing Ruby on Ubuntu

Before using RVM, I was using the default Ruby installation on Ubuntu. Then, I needed different versions of Ruby and started messing around with installing other Rubies. Apparently, I messed up my default Ruby install without knowing it. Then, I moved off to RVM and never looked back.

Recently, I needed my system Ruby again. This is when I found out it was completely messed. It kept giving me this error when I tried to use RubyGems.
'require': no such file to load -- thread (LoadError)

This was supposed to be impossible since thread is in the core library of Ruby. Then, I tried other things like requiring pp and date. Both gave me the same error.

I attempted to reinstall Ruby.
sudo apt-get purge ruby ruby-dev ruby1.8 ruby1.8-dev rubygems rubygems1.8
sudo apt-get install ruby ruby-dev rubygems

Unfortunately, this didn't help at all. I tried this several times to no avail. I then tried installing RubyGems through the source, but I couldn't even run setup.rb since it requires core libraries.

I decided to look through Synaptic Package Manager for anything that matched Ruby. That's when I realized I hadn't uninstalled all of Ruby. I had missed the Ruby libraries! Duh! I had messed up my Ruby libraries and wasn't reinstalling it.
sudo apt-get purge libruby libruby1.8
sudo apt-get install libruby

This fixed my require problems and all was right again.

Friday, November 5, 2010

Brother HL-2170W: Installation Gotchas + Reset to Factory Settings

Using Ubuntu 10.04, I decided to install this brand new printer and enable wireless printing. If you are using a USB cable, just plug-and-play. It just works. If you are planning to use wireless, read on!

Network Cable

You will need an extra network cable if your computer doesn't have wireless.

Wireless Authentication

The first gotcha is wireless authentication. This printer seems to behave properly only with AES encryption. TKIP will not work. Go ahead and change your settings from your router. I'll wait.

Wireless Setup

Get hold of a Windows or Mac machine. You NEED this in order to setup wireless. Ubuntu does not have an interface to this part of the printer. Unfortunately, you will need the CDs that come with the printer as well. Plop the CD into your computer and run it. A wizard will show up. It's pretty straightforward until you get to the "Top Menu". Here, you need to click the following:
  1. Install Printer Driver (even though we just want to setup wireless)
  2. Wireless Network users (window pops up)
  3. Wireless Setup Only
  4. Step by Step install
From here, follow the rest of the wizard. It should detect your printer and allow you to configure settings such as IP address (if you decided to use static IP) and wireless authentication. Fill it all in. At the end, it will tell you to unplug the network cable from the printer and ask if you want to print the settings. Make sure you print the settings. If anything goes wrong, it tells you on the print-out. When I wasn't using AES encryption, I had "Failed To Associate" under "Wireless Link Status".

MAC Addresses

If you do anything with MAC addresses, the second gotcha is that the wired interface and the wireless interface have different MAC addresses. Be careful that you use the wireless one.


Time to add the printer! Go to System > Administration > Printing > Add. Wait for a little bit. The New Printer popup should automatically detect your printer. Here's the third gotcha. I saw two. One that said "LPD network printer via DNS-SD" and one where it asked for Host (Probe) and Queue. You must select the DNS-SD one. The other one doesn't work! After selecting DNS-SD, it should look for drivers and then ask to print a test page. Make sure the test page prints.


Reset to Factory Settings

In case you screw up the settings and can't access the printer anymore, you can reset it to factory settings.
  1. Turn off the printer using the switch on the side.
  2. While holding down the Go button (big button that lights up blue in the corner), turn the switch on.
  3. Hold the Go button until the Toner, Drum, and Error lights turn on (this may be immediate).
  4. Let go of the Go button.
  5. Wait for the Toner, Drum, and Error lights to turn off (this may be immediate).
  6. Press the Go button 7 times. 
  7. The Toner, Drum, and Error lights should light up after the 7th time. This means the printer has been reset to factory settings.