TDD in Ruby Course

Sunday, March 29, 2015

The Scientific Method is Crap : Teman Cooke at TED

Great presentation explaining why it is Crap. He is right. How do you explain discoveries that were made by accident? Instead of the Scientific Method, we can adopt:

Cycle of Scientific Thinking

Model (Hypothesis)
Testing / Checking

Friday, February 27, 2015

How to export specific columns in a table to a csv file in mysql

Go to the mysql prompt as usual and run the command:
select id, email from users INTO OUTFILE '/Users/zepho/temp/users.csv' FIELDS TERMINATED BY ',';

This will create a csv file with only id, email columns in the users table in the users.csv file.

ERROR 1 (HY000): Can't create/write to file '/var/empty/projects/gold' (Errcode: 2)
ERROR 1 (HY000): Can't create/write to file '/Users/zepho/temp/users.csv' (Errcode: 13)

If you get these errors run:

chmod 777  /Users/zepho/temp

Thursday, February 26, 2015

How to turn off Spring

Spring is a big headache in development environment. Creates weird issues like not being able to play in rails console and is a big waste of time. To turn off spring, in the terminal, run:

You will now be able to go to rails console.  You may also have to kill any stray rails
console processes that may be running but never succeeded.

To remove it :
  • 'Unspring' your bin/ executables: bin/spring binstub --remove --all
  • Remove spring from your Gemfile

Saturday, February 21, 2015

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2) Mac OS 10.9.5

I was able to connect to the server using SQL Pro but not from the command line. The solution:

$ mysql -h -P 3306 -u root -p

You can also use telnet to check the connectivity:

$telnet 3306
Connected to localhost.
Escape character is '^]'.
5.6.21 81/8j0O?Am$fZn<||}~!mysql_native_password

!#08S01Got packets out of orderConnection closed by foreign host.

Friday, February 20, 2015

Is TDD Dead Part 3 Transcript Concise Version : Fast Feedback and Quality Assurance

Kent said that decisions involving TDD were about trade-offs: "In some ideal world we would have instant, infallible feedback about our programming decisions", "every key stroke that I make, if the code is ready to deploy, it would just instantly deploy." But that ideal is impossible at the moment so the question is how far do we back off from that. He went to enumerate several constraints in the trade-off.

  • Frequency: how rapidly do we want our feedback ?
  • Fidelity: how accurate do we want the red/green signal to be?
  • Overhead: how much are we prepared to pay?
  • Lifespan: how long is this software going to be around, which is a probability as well as time.

Those four are the constraints he thinks we need to compare. "My personal goal is just to understand the set of trade-offs by articulating them to people who are prepared to tear my ideas apart in a constructive way"

Fowler outlined three things that we can look at, to get feedback on:

  1. Is the software doing something useful for the user of the software?
  2. Have I broken anything? 
  3. Is my code-base healthy? This so I can continue to build things quickly.

David introduced the topic that TDD's success had led to a neglect of QA. The other issue is that to understand trade-offs you have to understand the costs, all the talk of TDD has been on the benefits. This neglect of costs is why people cannot comprehend that there is such a thing as test-induced damage. The trade-off continuum is true of other things. Consider the cost of reliability: going from 99% to 99.999% is exponentially more expensive than getting to 99%. We must also consider criticality. High reliability is important for space shuttles and pacemakers, but wrong for an exploratory web site. The rule of not writing a line of production code without a test doesn't fit in with trade-offs around criticality.

David agreed that it was good to mindfully trade-off QA for initial speed, but some have taken programmer testing too far and don't see the value of exploratory testing. Your tests may be green but when it's in production users do things you don't expect.

David says that worst of all is when developers are not part of of customer service. Many programmers don't want to be on-call because it's drudgery, but it's also a feedback loop. Code with green tests can be a plateau that's below where you want to be. "The on-call is the feedback loop that teaches you what tests you didn't write." As soon as you think you don't make mistakes any more, that's a mistake, and you stop growing. He'd rather pay the price of catching that early with a phone call at 2am.

How to use Favicon for your Rails 4.2 app

1. Copy your favicon.ico to app/assets/images folder.
2. In the layouts/application.html.erb add:  <%= favicon_link_tag %> within the head tags.
3. Deploy and enjoy!

Monday, February 16, 2015

Disabling SSL V3 for Poodle for Apache in Ubuntu

1. edit /etc/apache2/mods-available/ssl.conf
2. Look for : SSLProtocol All -SSLv2
3. Replace it with : SSLProtocol All -SSLv2 -SSLv3
4. Test configuration: apachectl configtest
5. Restart Apache : sudo service apache2 restart

Saturday, February 14, 2015

Auto Refresh Browser on File Save

I was looking for a tool that reloads static html pages automatically on file save. CodeKit does not work on Mac 10.7.5 and it costs $40. Here is a simple alternative.

1. Install Auto Reload Firefox Plugin
2. Go to Tools -> AutoReload Preferences and turn off notifications. It's a bit distracting.

3. Open the local html file in a text editor.

Now, whenever you save the file, the page will get refreshed automatically. Much faster feedback. I love it.