David Laing's thoughts on software development
I build cool stuff, well. [Read More …]
These are more for my reference purposes – hopefully you’ll find them useful:
If you’re about to name a class **Util; think harder – there is a better name that discribes what that class is for:
Chriss Missal has some advice for you
Faced with the prospect of heaps of left hand side => right hand side code in your DTO of anti-corruption layer? Consider Jimmy Bogard’s Automapper
Over the past month I’ve been experimenting with the pomodoro technique of time management to great success.
The technique is surprisingly simple; yet I’ve found it contains a wealth of physical and emotional benefits. To give some context; I’m using it as a programmer as part of a agile scrum team. I typically program using TDD techniques. That being said, I don’t see why it wouldn’t be applicable in most “desk” based jobs.
A pomodoro is a unit of focused, uninterrupted time; measured by an egg timer. For me, 25 minutes works well.
At the beginning of my work day, I write a collection of tasks that I think I achieve during the day onto a fresh piece of paper. (my todo list). I estimate how long I think each task will take in units of a pomodoros. Next to each task I put a number of boxes; one for each pomodoro unit. I make sure not to have more pomodoro units than I achieved yesterday; and I try to make sure that I’m estimating tasks based on how long similar tasks actually took me in the past.
Then I wind up my egg timer, place it visibly on my desk and begin the first task. The ritual of winding up the timer, placing it down and hearing it tick helps me to drop into the zone of full concentration – and let my team know that they shouldn’t interrupt me.
Brrrriiinng. Pomodoro up, finish the current test and stop. Cross out one of the boxes on my todo list. Get up and leave my desk; stretch, drink some water, focus on something far away to relax the eyes, go and speak to anyone who came past during my pomodoro time & was waived away.
Then back to the desk, reassess which is now the most important task to get one with, and start the next pomodoro.
At the end of the day I transcribe the results of my todo list back to a records sheet; update our project management software (VersionOne); and leave, satisfied that I achieved what I set out to do.
I’ve found that running my day like this greatly increases my job satisfaction & efficiency.
Firstly; I’m breaking my addition to hopium, and setting myself up to fail every day. I used to live in this lala land called – I have 8 hours of productive work time each day. The empirical reality shows that I usually do 5 – 8 pomodoro units / day – so much more like 3 – 4 hours. The rest gets gobbled up by meetings, emails, conversations. So its no wonder that I used to achieved half what I thought I would each day; and left work feeling disappointed.
Secondly, having a forced reset every 25 mins really helps me to stop falling down rabbit holes. I’ll often be trying to solve a problem with a specific technique that just isn’t working, and if I’m not careful I can spend a whole afternoon bashing my head against a wall. With the forced breaks, I’ll often find that when I sit back down to the problem, I’ll have a flash of inspiration for a much simpler way to solve it, or realise that I don’t even need to solve it in the first place!
Thirdly, being reminded to get away from my desk frequently really helps physically. I’ve experienced much less “mouse shoulder” and dry eyes.
The technique is also really helpful when pairing; keeping meetings from rambling; keeping focussed on one task (rather than having to check email or twitter every 10 seconds) and getting going on a large daunting task.
If you struggle with hopium like me; I’d really encourage you to give the Pomodori technique a try for 2 weeks, and let me know how you get on in the comments to this post.
Brrriiinng 
Resources
www.pomodorotechnique.com
I was involved in an interesting group discussion with fellow craftsmen yesterday on Technical Debt at the 2009 Software Craftsmanship conference.
The question put to the group was: “How should a team make time to reduce technical debt?”
I was interested that there was a totally unanamious response – “You shouldn’t”. “You should be doing tiny pieces of technical debt reduction all the time”.
Previously I have advocated creating technical debt reduction stories, and trying to schedule those into the iteration plan. People thought this was in principal the wrong strategy; and indeed in my experience this approach doesn’t work.
The group felt that in general tackling technical debt reduction though large scale refactorings was the wrong approach – rather a craftsman should be making incremental improvements every time they touch the code.
Bob Martin’s Boy Scout Rule: – check in your code a little cleaner than what you checked out – encapsulates this principal. Its the little refactorings that you make – removing a tiny piece of duplication, changing a variable name to better reveal intent; extracting an expression into a intention revealing method – that, over time, result in a clean, maintainable code base.
In a way, this is similar to implementing the “Fixing Broken Windows Theory” in software development. The theory is that having a zero tolerance attitude towards the little things makes a huge impact on the so called “bigger” things.
Its perhaps easier understood if you consider what happens if you don’t care about the little things. Its about the attitude – if I couldn’t care enough to clean up a messy bit of code; will my team mates care about a few broken tests? If its okay to have a few broken tests; then it’s probably okay to ignore some bugs. If its okay to ignore bugs; then who really needs to care about well defined acceptance tests? And if the team doesn’t care about precise acceptance tests; why should the business care about unambiguous requirements. You get the picture.
Its the little things, added up, that result in technical debt reduction.
Today I fell into a trap when using a function that had a side effect – it unexpectedly changed an input parameter; causing a later statement to fail. Debugging took an age!
For example, consider the following function:
string StringReplace(string haystack, string needle)
If this function is side-effect free, we can use it without fear like this:
string menagerie = "cat,dog,bee,llama";
string catFreeMenagerie = StringReplace(menagerie, "cat");
string beeFreeMengerie = StringReplace(menagerie, "eric");
Assert.AreEqual(",dog,fish,llama", catFreeMenagerie);
Assert.AreEqual("cat,dog,,llama", beeFreeMengerie);
However, if StringReplace() had the side effect of also changing the passed in haystack, then the second Assert would fail, because the first StringReplace has the unexpected side effect of changing one of its arguments.
Evans in the DDD book has quite a bit to say about this; arguing that having side effect free functions goes a long way towards making a supple design
Side effect free functions also make testing & refactoring easier (less state to worry about etc)
Remember, a function that changes its parameters is rude, and should not be trusted!
Whilst writing some Selenium based acceptance tests today; I bumped into a hair pulling gotcha. Hopefully this post will prevent you from the same pain.
The test was to check whether some tracking tag javascript was being inserted into the page correctly or not.
I assumed that I could get the page source as it was being delivered to the browser by calling selenium.GetHtmlSource(); and then check that for the javascript string I was expected.
Unfortunately, GetHtmlSource is just a proxy for the browsers DOM.InnerHTML method; and that returns the Html after it has been preprocessed by the browser.
Turns out that preprocessing does a couple of funky things, including
So, when I was expecting a string like this:
<!-- var amPid = '206''; var amPPid = '4803'; if (document.location.protocol=='https:') ...[snip]...
IE6 was presenting me with:
<!-- var amPid = '206''; var amPPid = '4803'; if (document.location.protocol=='https:') ...[snip]...
A possible solution is to ignore case, whitespace and quotes when doing the comparison, with a helper method like this:
////// Use this to compare strings to those returned from selenium.GetHtmlSource for an Internet Explore instance /// (IE6 seems to change case and inclusion of quotes, especially for Javascript.?) /// /// /// private static void AssertStringContainsIgnoreCaseWhiteSpaceAndQuotes(string expected, string actual) { string expectedClean = Regex.Replace(expected, @"s", "").ToLower().Replace(""","").Replace("'",""); string actualClean = Regex.Replace(actual, @"s", "").ToLower().Replace(""", "").Replace("'", ""); StringAssert.Contains(expectedClean,actualClean, string.Format("Expected string nn{0} nnis not contained within nn{1}", expected, actual)); }
It was the line endings that really floored me; because they were automatically normalized/corrected by my test runner when displaying the error. Aaargh!
Whenever I start working on a project; I invariably find myself writing a collection of TDD test helper methods. I quick survey of other TDDers reveals the same; and thus the birth of my latest opensource project, TestHelpers (http://code.google.com/p/testhelpers/).
The aim of the project is to centralise all those little test helper methods you end up creating into a useful assembly you can use to jumpstart your next project. Things like:
For example, I’ve just added an “AssertValues” functor; which helps you check whether the values of who object instances are the same.
One area I keep using asserts like this is in integration tests; where I want to check that the objects I’m persisting to the database via my ORM actually end up in the database in a non-mangled form. In this case, I new up entityA, persist it, reload it into entityB and then need to check that all the values in entityB are the same as those in entityA.
A standard Assert.AreEqual will fail, because entityA and entityB are different instances. But, my helper method AssertValues.AreEqual will pass, because it checks the (serialized) string values of entityA and entityB.
Here is another, simpler example to illustrate the concept.
[TestFixture]
public class StandardObjectsTests
{
public class StringContainer
{
public string String1 { get; set; }
public string String2 { get; set; }
}
[Test]
public void ObjectsWithSameValue_ShouldBeEqual()
{
var stringContainer1 = new StringContainer {String1 = "Test String1", String2 = "Test String 2"};
var stringContainer2 = new StringContainer {String1 = "Test String1", String2 = "Test String 2"};
Assert.AreNotEqual(stringContainer1, stringContainer2);
AssertValues.AreEqual(stringContainer1, stringContainer2);
}
}
I’m sure you have a bunch of similar helper methods lying about your projects.
How about contributing them to the TestHelper project?
Intro
Debate over what ALT.NET is; should it have a set of guiding principles like the Agile manifesto?
Continuous integration & deployment
There seemed to be 3 major areas where people encountered difficulties doing continuous integration & deployment.
Image via Wikipedia Besides precisely pinning functionality, writing text based stories has another – and some would argue more important – benefit, developing a shared domain language between the business & developers.
A large part of developing a new software application is defining and codifying a business solution. To do this, both sides of the equation must be molded to fit the constraints of the other – the business process needs to be expressed in a precise manner that can be automated in software, and software must be molded to fit the use cases of its users.
The mismatch between the way the business sees the solution, and the way the developers view the solution becomes painfully obvious about half way into the project, when you start to try to match what data fields are labeled on the UI, and what they are called in the database / object model.
I’ve worked on what should have been simple projects; where maintenance is a exercise in hair pulling as you try to figure out what data input results in the weird output in a report.
The root problem is a lack of a shared domain language. Projects naturally evolve domain languages; and unless guided, you can guarantee that the language in the customers requirements spec and that in the code base will diverge rapidly.
Sitting developers, testers and the customer together to produce written text user stories following Dan North’s classic BDD story structure goes a long way towards resolving this issue.
Talking through how functionality will work, and being forced to formalize it by writing things down helps the domain understanding and language to evolve naturally, influenced equally by the customers domain understanding, and the constraints the developer must work within.
Its vital that this is done before coding begins for the following reasons:
During release planning, the high level “As a [x] I want [Y] so that [Z]” is probably sufficient, with the “Given, When, Then” acceptance scenario’s being fleshed out at the beginning of each sprint.
Specifying your functional requirements as text stories leads to some exciting opportunities:
The Ruby community has made the most progress in the latter opportunity, with their rSpec story runner.
Consider the possibilities of the following development practice:
At any stage its possible to see how far the team is (how many steps pass?), speculative complexity is reduced because the developers are focused on developing only that which the test requires, and all the while a suite of regression tests are being build up!
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Luke Francl of Tumblon has a nice summary with backing research showing how unit testing is only part of the QA story.
Its important to realise that developers by nature will only test the happy path; hence its likely that those diabolical edge cases will remain untested by a developer.
Another important factor is that most bugs come from missing features or requirements; and its impossible to unit test what isn’t there.
See more at http://railspikes.com/2008/7/11/testing-is-overrated; specifically Luke’s create Venn diagram showing how different types of testing (unit, user, code review etc) uncover different types of defects.
This isn’t to say that unit testing isn’t worthwhile; it just frees your testers up to concentrate on the unexpected, non-logical things that users are sure to try use your software for