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Avoid these Things When Logging from Your Application

Editorial note: I originally wrote this post for the LogEntries blog.  You can check out the original here, at their site.  While you’re there, sign up for the service and check it out.

It seems almost strange to talk about avoiding things while logging.  After all, logging is your last line of defense or your salvation in many cases.  Some crazy bug in the field that shows up every third full moon?  An external auditor looking at your app’s runtime behavior?  Logging to the rescue.

So naturally, is stands to reason that you would want to log just about everything your application.  Whenever there’s any doubt, slam a logger call in there and let log level sort out the details.  You can always filter logs, but you can’t magic stuff into them after the fact.  So why, then, talk of avoidance?

wizard

Well, it turns out that, while logging may be a highly inclusive activity in terms of what should be included, there are ways to create problems.  You want to be liberal in terms of what you log, but judicious and wise in terms of how you log it.  You don’t want to indulge in a feckless free-for-all when it comes to the calls you make to your application’s logger.

So what are these problems, and how to avoid them?  Let’s take a look at some things that can come back to bite you.

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Keeping Your Code Clean while Logging

Editorial Note: I originally wrote this post for the LogEntries blog.  You can check out the original here, at their site.  While you’re there, take a look at their product offering that handles your log aggregation, search, and alerting needs.

In my consultancy practice, one of the things that I do most frequently is help teams write so-called “clean code.”  Usually, this orients around test-driven development (TDD) and writing code that is easily maintained via regression tests and risk-free refactoring.  Teams want to understand how to do this, and how to do it in their production code (as opposed to in some kind of toy “let’s build a calculator” exercise).

BrandNewSetup

One of the most prominent, early sticking points that rears its head tends to be application logging.  Why?  Unit testing is all about isolating objects, instantiating them, and rapidly verifying their behavior in memory.  Logging is all about dumping as much information as possible to a file (or database, service, etc with appenders) from as many places as possible.  Unstoppable force, meet immovable object.

For instance, consider the following C# code from a “let’s build a calculator” exercise.

Life here is good.  The calculator’s add method returns the sum of the integers, and we have a test method that supplies 2 and 2, and confirms a result of 4.  That’s a screaming fast, very clear test.  But, consider what happens if we amend our calculator to take advantage of logging.

Now, with that same test, everything goes wrong.  Instead of passing, it throws an exception about not having write access to some weird directory on your machine that you’ve never even heard of.  After digging a bit, you see that it’s the directory in which the test runner executes when running your solution’s tests.  Hmmm.

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The Power of CQLinq for Developers

Editorial Note: I originally wrote this post for the NDepend blog. Check out the original here, at their site.  While you’re there, have a look around at some of the other posts and subscribe to the RSS feed if you’d like a weekly post about static analysis.  

I can still remember my reaction to Linq when I was first exposed to it.  And I mean my very first reaction.  You’d think, as a connoisseur of the programming profession, it would have been, “wow, groundbreaking!”  But, really, it was, “wait, what?  Why?!”  I couldn’t fathom why we’d want to merge SQL queries with application languages.

Up until that point, a little after .NET 3.5 shipped, I’d done most of my programming in PHP, C++ and Java (and, if I’m being totally honest, a good bit of VB6 and VBA that I could never seem to escape).  I was new to C#, and, at that time, it didn’t seem much different than Java.  And, in all of these languages, there was a nice, established pattern.  Application languages were where you wrote loops and business logic and such, and parameterized SQL strings were where you defined how you’d query the database.  I’d just gotten to the point where ORMs were second nature.  And now, here was something weird.

But, I would quickly realize, here was something powerful.

Nascar

The object oriented languages that I mentioned (and whatever PHP is) are imperative languages.  This means that you’re giving the compiler/interpreter a step by step series of instructions on how to do something.  “For an integer i, start at zero, increment by one, continue if less than 10, and for each integer…”   SQL, on the other hand, is a declarative language.  You describe what you want, and let something else (e.g. the RDBMS server) sort out the details.  “I want all of the customer records where the customer’s city is ‘Chicago’ and the customer is less than 40 years old — you figure out how to do that and just give me the results.”

And now, all of a sudden, an object oriented language could be declarative.  I didn’t have to write loop boilerplate anymore!

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Rethinking Assert with Shouldly

I was doing a bit of work with Tweetdeck open, when I noticed this tweet.

I’ve been using Assert.IsTrue() and its friends for years, so you might think I would take offense.  But instead, this struck me as an interesting and provocative statement.  I scanned through the conversation this started and it got me to thinking.

Over the years, I’ve evolved my unit tests heavily in the name of readability.  I’ve come to favor mocking frameworks on the basis of having fluent APIs and readable setup.  On a pointer from Steve Smith, I’ve adopted his philosophy and approach to naming unit test classes and tests.  My arrange and act inside of the tests have become highly readable and optimized for comprehension.

But then, there’s Assert.AreEqual.  Same as it ever was.

WorkHarder

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Chess TDD 62: Finishing Chess TDD

You might not have expected to read this, and I honestly wasn’t really expecting to write it, but here we are.  I’m going to call it and announce that I’m finishing Chess TDD series.  It’s been a lot of fun and gone on for a long time, and I’m not actually done with the codebase (more on that shortly).

My original intention, after finishing the initial implementation with acceptance and unit tests, was to walk through some actual games, by way of “field testing,” so to speak.  I thought this would simulate QA to some extent — at least as well as you can with a one person operation.  And, with this episode, I’ve showed a tiny taste of what that could look like.  And, I’ve realized, I could go on this way, but that would start to get pretty boring.  And, I’ve also realized that it would be irresponsible.

What I mean is that plugging laboriously through every piece on the board after every move would be showing you a “work harder, not smarter” approach that I don’t advocate.  I’d said that I would save ingesting chess games and using algebraic notation for an upcoming product, and that is true — I plan to do that.  But what I shouldn’t be doing in the interim is saving the smart work for the product and treating you to brainless, boring work in the meantime.

So with that in mind, I brought the work I was doing to a graceful close, wrapping up the feature where initial board positioning was shown to work, and using red-green-refactor to do it.

You’ll notice in the video that the Trello board is not empty by a long shot.  There’s a long list of stuff I’d like to tweak and make better as well as peripheral features that I’d like to add.  But, to use this as a metaphor for business, I have a product that (as best I can tell) successfully tells you all moves available to any piece, and that was the original charter.  It’s shippable, and, better yet, it’s covered with a robust test suite that will make it easy to build on.

What should you look for in the product?  Here are some ideas that I have, off the top (and from Trello).

  • A way to overlay algebraic chess notation for acceptance tests.
  • Remove type checking for a polymorphic scheme.
  • Improve the object graph with better responsibilities (e.g. removing En Passant logic from Board)
  • Apply static analysis tooling to address shortcomings in the code.
  • Make sure that piece movement also works properly (currently it probably wouldn’t for castling/en passant).
  • Develop a scheme for ingesting chess games and verifying that our possibilities/play match.

In short, what I have in mind is bringing this application along with the kinds of work I’d advise the teams that I train/coach and assess.  Here’s how to really make this codebase shine.

I have a couple of things to get off my plate before I productize this, but it’s not going to fall off my radar.  Stay tuned!  And, until then, here is the last of the Chess TDD posts in the format you’re accustomed to.

What I accomplish in this clip:

  • Finish the testing of the initial rows on the board.

Here are some lessons to take away:

  • The new C# language features (as of 6) are pretty great for making your code more compact and functional-appearing in nature.
  • Always, always, always make sure that you’re refactoring only when all tests are green.  I’ve experienced the pain of not heeding this advice, and it’s maddening.  This is a “measure twice, cut once” kind of scenario.
  • Clean, consistent abstractions are important for readability.  If you think of them, spend a little extra time to make sure they’re in place.
  • If something goes wrong with the continuous test runner or your test suite in general, pause and fix it when you notice it.  Don’t accept on faith that “everything should be passing.”  Like refactoring when red because “it’s just a trivial change,” this can result in worlds of downstream pain.