Dynamically Creating a Test Suite in JUnit 4 -- cpsuite

 

http://stackoverflow.com/questions/3257080/how-do-i-dynamically-create-a-test-suite-in-junit-4

 

http://johanneslink.net/projects/cpsuite.jsp

 

Regex and Lookahead/Lookbehind

http://www.regular-expressions.info/lookaround.html

E.g. to remove all @Component annotations from non-"Default" classes:

search for (negative lookahead):
@Component\npublic class (?!Default)

replace with:
public class


negative lookahead: q(?!u) matches a "q" not followed by a "u"


positive lookahead:  q(?=u) matches a q that is followed by a u, without making the u part of the match


If you want to store the match of the regex inside a backreference, you have to put capturing parentheses around the regex inside the lookahead, like this:(?=(regex)). 


negative lookbehind: (?<!a)b matches a "b" that is not preceded by an "a", using negative lookbehind.


positive lookbehind: (?<=a)b matches the b (and only the b) in cab

Java XML XPath

Converted from Groovy: http://docs.codehaus.org/display/GROOVY/Reading+XML+with+Groovy+and+XPath

 

import org.apache.xml.dtm.ref.DTMNodeList;

import org.w3c.dom.Element;

import org.xml.sax.SAXException;

 

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.parsers.ParserConfigurationException;

import javax.xml.xpath.XPath;

import javax.xml.xpath.XPathConstants;

import javax.xml.xpath.XPathExpressionException;

import javax.xml.xpath.XPathFactory;

import java.io.ByteArrayInputStream;

import java.io.IOException;

import java.io.InputStream;

 

public class XPathTest extends TestCase {

    private static final String CAR_RECORDS = "<records>       <car name='HSV Maloo' make='Holden' year='2006'>         <country>Australia</country>         <record type='speed'>Production Pickup Truck with speed of 271kph</record>       </car>       <car name='P50' make='Peel' year='1962'>         <country>Isle of Man</country>         <record type='size'>Smallest Street-Legal Car at 99cm wide and 59 kg in weight</record>       </car>       <car name='Royale' make='Bugatti' year='1931'>         <country>France</country>         <record type='price'>Most Valuable Car at $15 million</record>       </car>     </records> ";

 

    public void test() throws ParserConfigurationException, IOException, SAXException, XPathExpressionException {

        DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();

        InputStream inputStream = new ByteArrayInputStream(CAR_RECORDS.getBytes());

        Element records = builder.parse(inputStream).getDocumentElement();

        XPath xpath = XPathFactory.newInstance().newXPath();

        DTMNodeList nodes = (DTMNodeList) xpath.evaluate("//car", records, XPathConstants.NODESET);

        for (int i = 0; i < nodes.getLength(); i++) {

            org.w3c.dom.Node node = nodes.item(i);

            String make = xpath.evaluate("@make", node);

            String country = xpath.evaluate("country/text()", node);

            String type = xpath.evaluate("record/@type", node);

            System.out.println(make + " of " + country + " has a " + type + " record");

        }

    }

 

}

Coffee with Robert Virding

Had a fascinating conversation over coffee with Robert Virding at Yow Conference Tuesday 6th December 2011... jotted down some of the things I remembered:

• "erlc" produces a BEAM file which is portable byte code
• Joe's Abstract Machine originally compiled Erlang to C macros which was then JIT translated to machine code on the fly
• BEAM was a complete rewrite to produce portable byte code that "erl" translates to machine code on the fly
• Erjang runs on the JVM so it has the advantage of many years and many people of JVM optimisation... Erlang has a team of 5 developers working on the VM.
• Architecture of Erlang apps
• Processes that do the work don't contain error handling... error handling is done where and when it matters by supervisor processes further up the tree
• Supervisor processes are responsible for determining how to handle different types of errors
• Some people on stack overflow freak out about this idea of letting processes crash but don't realise that approach goes hand-in-hand with the approach of handling errors higher up the process tree
• Error Handling
• Modular approach
• Robert likes to code for all eventualities but often developers take an iterative approach... code the core functionality in processes... run the app, observe how different errors crash the processes... and work out how (and where) they should be captured and dealt with
• Processes are organised in trees.  A supervisor at the top is responsible for working out what to do when different types of errors occur
• Typical approach is to let type errors crash the process
• Erlang movie 
• Robert was the guy who "fixed the bug"
• This patching code fixes while the app is running is possible through module loading
• The app has to be specifically designed with this approach in mind
• Have to be careful... what if the process is already running?  
• A module could  (and typically does) contain both the server code and the client code used to access the server.  So a module could contain code that is running in separate processes - a client process, a server process.  Updating it on the fly is tricky.
• Need to take into account data changes too... a mini data migration might be required on existing state... it's up to the module author what they're going to do
• Sometimes the best approach is to crash the process and restart it rather than carry all that complexity in the code - depends on the scenario.
• Also, restarting the entire app is an option... 
• Or using a load balancer type approach where the router directs the traffic to the new server.
• Some companies use Erlang as essentially a gateway to processes running on other languages
• e.g. a fast server server that accepts many concurrent connections and directs each connection to a backend C process.
• Erlang NIFs (Natively Implemented Functions) are invoked in a similar manner to Java's JNI interface
• Erlang can call into Java code using the JInterface
• I remarked I was surprised that I couldn't call my own function from a guard and I understood this was because Erlang didn't want you doing side effects during a guard statement
• Guards where really just an extension on pattern matching, enabling you to be a little more verbose
• Can't create your own data types but can use a Binary type which lets you compose data out of other Erlang types.
• Can reuse the same binary block with other binary types e.g. if your binary type has Int,String,Bool... you could reuse a variable of that binary type as a different type
• Erjang
• serious implementation of Erlang on JVM
• Robert hopes good things come out of it
• Tricky job though to keep up with Erlang as it is still evolving within Ericsson
• Ericsson's OTP department maintain the Erlang language
• Used mainly for testing
• Surprising that a telecoms hardware company supported the language from infancy and there was initially some tension with others who didn't like it but the OTP team had sympathetic management
• Was Erlang based on Prolog?
• It was originally implemented on Prolog (eventually rewritten in Erlang itself)
• The syntax was influenced a little by Prolog but logic programming wasn't the main thrust - it was more about solving telephony concurrency problems.
• Where did the functional programming syntax come from?
• Realised after a bit that the language needed some of the benefits of FP and so they were added
• Do you find many type errors come out in runtime when a particular piece of code that wasn't exercised during testing is invoked due to the input of different data?
• Not so much... there's a tool called the Dialyser that you run over your code... it actively tests all your types and tells you where there's a programming error in your code - it's able to catch most of the programming errors that could lead to a type error at runtime.
• Hipe:  http://www.it.uu.se/research/group/hipe/
• Popularity of Erlang
• It's been pretty steady... there was a bit of a peak in 2008/09

Erlang setup

Install

• Download and install from: the official Erlang website  (http://learnyousomeerlang.com/introduction#what-you-need)

Compile & Run

• http://learnyousomeerlang.com/modules
• c:\erlangcode> erlc program.erl 
• c:\erlangcode> erl program
• 1> program:function().

Displaying Groovy Classpath

http://marxsoftware.blogspot.com/2010/01/viewing-groovy-applications-classpath.html
this.class.classLoader.rootLoader.URLs.each{ println it } 

http://blog.blindgaenger.net/print_groovys_classpath_for_debugging.html

def printClassPath(classLoader) {
  println "$classLoader"
  classLoader.getURLs().each {url->
     println "- ${url.toString()}"
  }
  if (classLoader.parent) {
     printClassPath(classLoader.parent)
  }
}
printClassPath this.class.classLoader

 

Imaginary Boss

"I have an imaginary boss in my head. I'm still scared if I'm late coming in to work. Everybody else has someone to drive them, I had to find that discipline within myself."

Yoganathan Ratheesan of Lebara

http://www.smh.com.au/it-pro/business-it/virtual-phone-network-a-real-moneymaker-20111118-1nm28.html

 

git push putty disconnected error

PuTTY Fatal Error: Disconnected: No supported authentication methods available"

http://stackoverflow.com/questions/3431314/github-no-supported-authentication-methods-available

set GIT_SSH=c:\progra~2\git\bin\ssh.exe

Snap: Haskell Web Framework

http://snapframework.com/docs/quickstart
http://snapframework.com/docs/tutorials/snap-api


cabal update
cabal install snap  -- installs into C:\Users\<user>\AppData\Roaming\cabal  (or $HOME/.cabal/) (10mins)
mkdir snapblog
cd snapblog
snap init -- creates .ghci, snapblog.cabal, <src>, <log>, <resources>
cabal install  -- installs executable snap (snapblog.exe) into C:\Users\<user>\AppData\Roaming\cabal\bin  (or $HOME/.cabal/bin)
snapblog -p 8000

Needle: Automated tests for your CSS

http://needle.readthedocs.org/en/latest/index.html

On the goals of Coderetreat

On the goals of Coderetreat

Corey Haines Intro: http://vimeo.com/18955165

http://www.infoq.com/news/2011/11/global_day_of_code_retreat

"The Principles of Product Development Flow: Second Generation Lean Product Development" by Donald G. Reinertsen

"The Principles of Product Development Flow: Second Generation Lean Product Development" by Donald G. Reinertsen

 

http://www.startuplessonslearned.com/2009/07/principles-of-product-development-flow.html

 

 

It should be obvious that fast feedback improves the speed of learning. What may be less obvious is that fast feedback also increases the efficiency with which we generate information and learn new things. It does this by compressing the time between cause and effect. When this time is short, there are fewer extraneous signals that can introduce noise into our experiment.

Team New Zealand designed the yacht that won the America's Cup. When they tested improvements in keel designs, they used two virtually identical boats. The unimproved boat would sail against the improved boat to determine the effect of a design change. By sailing one boat against the other, they were able to discriminate small changes in performance very quickly.

In contrast, the competing American design team used a single boat supplemented by computer models and NASA wind tunnels. The Americans could never do comparison runs under truly identical conditions because the runs were separated in time ...

Team New Zealand completed many more cycles of learning, and they generated more information in each cycle. This ultimately enabled them to triumph over a much better funded American team. It is worth noting that Team New Zealand explicitly invested in a second boat to create this superior test environment. It is common that we must invest in creating a superior development environment in order to extract the smaller signals that come with fast feedback.

Java Date encapsulation

http://c2.com/cgi/wiki?JavaUtilDate

 

When we design systems, we need to decide what it is (out of all the many different things we could do with dates) that we actually want to do in each instance. Then we should encapsulate just that functionality in our own classes, delegating where appropriate to java.util.Date, java.util.Calendar and java.text.DataFormat?. Importantly, we must decide how we compare, add and subtract intervals, and how we will display each type of date.

 

See http://joda-time.sourceforge.net for alternative

Haskell, lazy, dataflow, declarative

• http://en.wikipedia.org/wiki/Haskell_(programming_language)
• http://en.wikipedia.org/wiki/Non-strict_programming_language
• http://en.wikipedia.org/wiki/Lazy_evaluation
• http://en.wikipedia.org/wiki/Dataflow
• https://github.com/larrytheliquid/dataflow
• http://en.wikipedia.org/wiki/Declarative_programming
• http://en.wikipedia.org/wiki/Comparison_of_programming_paradigms
  
  

Steve Jobs: Life is made up

http://www.cultofmac.com/127707/reminder-watch-the-steve-jobs-one-last-thing-documentary-tonight-on-pbs-and-channel-4-in-the-uk/

 

ONE LAST THING takes an unflinching look at Jobs's difficult, controlling disposition, and offers unique insights into what made him tick. While there has been near-universal agreement that Steve Jobs was a great innovator in business and technology, ONE LAST THING looks into why he was so great. What were the influences that shaped his character? What drove him from such humble beginnings to the heights of success?

 

In a never-before-broadcast interview from 1994, Jobs expounds on his philosophy of life: "You tend to get told that the world is the way it is, but life can be much broader once you discover one simple fact; and that is that everything around you that you call life was made up by people no smarter than you … Once you learn that, you'll never be the same again."