All articles are written by Jeff Langr unless otherwise noted. All of the articles on this page were either published in print magazines, at other sites, or submitted to conferences.
25 Apr 2019
In this blog post for Ranorex, I provide two key rules for making mob programming a successful and enjoyable way to work. You’ll figure out most of the rest of the guidelines for mobbing yourself: Things like respect for your teammates, guidelines about people coming and going, and so on. But these two rules–while simple to employ–aren’t necessarily obvious, and they’ll make all the difference in the world between a tedious, protracted mobbing session and something you’ll actually enjoy quite a bit.
18 Feb 2019
In this blog post for Ranorex, I present OTAAT: One Thing At A Time, one of the most effective habits you can adopt as a software developer. From tackling stories to designing tests to refactoring, doing more than OTAAT is a guaranteed way to waste time. I’ll talk about how OTAAT instead helps makes life easier in general.
05 Nov 2018
I keep hearing from teams who are mobbing, where everyone is in the same room with a WIP limit of one, that “we go faster.” Really! How is that possible? In this blog post for Ranorex, I talk about my use of mobbing and pairing in training environments, then segue into a discussion of the value of minimizing WIP. Finally, I present a long list of reasons why mobbing might actually allow teams to go faster.
30 Oct 2018
“A test that passes with no change to your classes is always cause for humility and pause.” We learn red-green-refactor for a reason–it’s not just “green-refactor.” In this blog post for Ranorex, I talk about the various reasons why you might see tests pass (green) when expecting them to fail. You’ll learn why it’s important to stick to that TDD rhythm.
13 Sep 2018
Yes, coding standards are often a source of discontent within a team… but if you can’t get past agreeing on a few simple things, I suspect that portends something. In this blog post for Ranorex, I talk about the value, or lack, of having coding standards. I present a set of recommendations for deriving “agile standards,” but ultimately distill all standards down to a singular concept.
30 Aug 2018
There’s no such thing as a free lunch, or free-expensive-steak dinner. You might have to listen to someone ramble about DevOps for hours while not being able to tell you what it is. In this blog post for Ranorex, I get to vent a little with a story about a steak dinner dominated by blather. I present a few thoughts about what DevOps is, since I can’t seem to find a concise definition anywhere (or get one at a steak dinner).
29 Aug 2018
XP presented four values as the basis for its approach to software development. Humility is perhaps the 5th, missing value. In this blog post for Gurock, I offer some thoughts on what it means to be humble. I relate humility to the unease that many seasoned developers feel about TDD–its insistence of building only the software needed to that point in time.
21 Aug 2018
Check out We Do TDD for numerous great stories about test-driven development from people, teams, and companies that test-drive their software. In this blog post for Ranorex, I talk about Dave Schinkel’s site that features interview questions and answers from a good number of TDD practitioners. I highlight some answers to questions about interesting TDD topics:
16 Aug 2018
No, there’s no one “right” way to practice TDD, though there are plenty of ways that technically are not TDD. In this blog post for Ranorex, I talk about some of the variant ways of approaching test-driven development (TDD). I first introduce two distinct ways of describing TDD. I then discuss “assert-first,” “one assert per test,” and how tests are best named (or not).
26 Jul 2018
Don’t create a long laundry list of technical buzzwords for hiring. There’s a better, more agile approach. In this blog post for Ranorex, I present six major points to consider when hiring someone for your agile team: three job requirements essentials, and three important aspects to consider during the hiring process.
16 Jul 2018
“The more you spread it, the thinner it gets,” said the late Gerald Weinberg. In this blog post for Ranorex, I talk about the mass growth of our industry, and how as a result developers have on average less experience than ever before. I talk about some ways in which we might thicken up that jam.
09 Jul 2018
Passive review after code (PRAC) is largely a waste of time. In this blog post for Ranorex, I provide some reasons why active review is better than PRAC. I discuss pairing and mobbings as two forms of active rule, and present a core rule for review that focuses on outcome instead of mechanism.
03 Jul 2018
With the July 2018 issue, PragPub magazine (edited by Michael Swaine) celebrates the beginning of its tenth year. This year also begins the 20th of Andy Hunt’s and Dave Thomas’s classic book The Pragmatic Programmer. In this article, I talk a bit about what it means to be pragmatic and about how both the book and magazine have helped us be pragmatic over the years.
22 Jun 2018
This blog post for Ranorex tells the story of a day in a life where we don’t talk about a process, we just live it, with the singular goal of delivering high-quality software frequently.
21 Jun 2018
I view modes of working as akin to tools–you want to use the right tool for the right job or situation. In this blog post for Gurock, I talk about the distinctions around appropriateness for mob programming and pair programming. I also admit to enjoying the ability to work alone from time to time.
07 Jun 2018
In this blog post for Ranorex, I present seven design principles for the tests you’ll craft as part of practicing behavior-driven development (BDD) or acceptance test-driven development (ATDD). Stick to these principles and you’ll create a body of tests that returns many benefits while allowing you to keep your sanity.
22 May 2018
In this blog post for Gurock, I wax rhapsodic about TDD… well, maybe not. I don’t love TDD itself; I love the things that TDD enables me to do. I talk about what those things are, along with a bit of my personal history about how I got here.
15 May 2018
In this blog post for Ranorex, you’ll pick up a number of ideas about how to approach introducing TDD into your team. While TDD is a simple practice to learn (though a challenge to master), getting developers to think they might want to even consider it is not an easy task. I’ll also talk about why resistance is to be expected.
15 Apr 2018
A number of good questions about BDD arose from the Gurock webinar “BDD Testing Skills.” I felt like answering them all, though I did so rather hastily (so don’t expect a lot of clean editing for this “article”).
02 Mar 2018
Why do TDD at all? In this blog post for Ranorex, I explain that my primary reason to do TDD is because it allows me to go faster, particularly as a system grows. I talk about some of the reasons why, and iterate some of the high cost of defects along the way.
23 Feb 2018
Yes you can. In this blog post for Gurock, I talk about a customer who didn’t realize the pickle they were brining themselves into when they slowly but surely found their way on a path to “too many” tests.
08 Feb 2018
This post for Ranorex’s blog talks about how behavior-driven development (BDD) can help us come to consensus. I share a story about a customer who found value in BDD, even though we were unable to automate their “specs by example.”
19 Jan 2018
In this article written for the Gurock blog, I talk about the values of negotiating around scenarios when doing behavior-driven development (BDD). Rather than delve deep into the narratives (given-when-thens), this focus will help when it comes to negotiating the scope of a given story.
17 Jan 2018
In this blog post for Gurock, I talk about my experiences doing test-driven development (TDD) at a small startup: Where did we succeed, where did we fail, and what would I change?
06 Jul 2016
A reflection on why I’ve found TDD to be an indispensable practice for the past sixth of a century. Published for PragPub–get the whole issue with a pile of great articles at The Prose Garden.
02 Mar 2016
Written with Tim Ottinger for AgileConnection. Much like in pair programming, working with a partner through pair writing provides increased support and valuable immediate feedback. But there are additional obstacles when you and your partner are not collocated. Here are some tips on how you can still implement pair writing successfully when you can’t collaborate in person.
01 Apr 2015
Written for PragPub. revisits his own coding history and finds it necessary to revise one of his basic principles. Along the way he shares some hard-won insights on how to make distributed development teams work.
01 Jan 2012
Written with Tim Ottinger for PragPub. Tim and I present a breakdown of the FIRST acronym, which presents five guidelines for good quality unit tests.
01 Dec 2011
Published in the Java Tech Journal, this article presents a laundry list of things you need to look for and monitor in a TDD shop. TDD is a significant investment and challenge; following these recommendations should help you more effectively sustain the practice over time.
02 Nov 2011
Written for PragPub. Want your manager to understand test-driven development (TDD)? This article overviews what TDD is and discusses its cost and benefits. Jeff also presents some thoughts on how non-programmers might understand whether or not their team is doing TDD well.
01 Oct 2011
Written with Tim Ottinger for PragPub. Is “distributed agile” an oxymoron or reality? Tim and I talk about distributed teams and agile values, covering a number of do’s and don’ts for agile teams. We also provide a number of communication guidelines for working distributed.
08 Sep 2011
Written with Tim Ottinger for PragPub. What low-tech tools can help in agile, and when and how should high-tech tools be used?
01 Aug 2011
Written with Tim Ottinger for PragPub. This article is based on the Agile in a Flash card “The Seven Code Virtues.” It presents yet another possible definition for letting us know when code is “good.”
06 Jul 2011
Written with Tim Ottinger for PragPub. We list over twenty benefits that you can derive from pair programming, categorized as being from the perspective of the team and system, programmers, and managers/project managers.
02 Jun 2011
Written with Tim Ottinger for PragPub. We discuss three of our Agile in a Flash pairing cards, covering the rules of pairing, pair programming smells, and what to do when not pairing.
02 May 2011
Written with Tim Ottinger for PragPub. Tim and I reflect on the various “agile development practices” (perhaps better classified as the technical practices from extreme programming).
02 Apr 2011
Written with Tim Ottinger for PragPub. Using smells that identify problems with respect to abstraction in your unit tests, we whittle down an ugly test (take from open source) into a pair of highly readable, maintainable tests.
02 Mar 2011
Written with Tim Ottinger for PragPub. The final in a series of four articles on the “big ideas” in software development. This article discusses what volatility is, what problems it can create, and how to begin controlling it.
08 Dec 2010
In a guest blog post at the RubyLearning Blog site, I talk about my experiences building quick’n’dirty scripts in Ruby and Python, and how that’s almost always a mistake.
01 Dec 2010
Written with Tim Ottinger for PragPub. Tim and I talk about one of the four “big ideas” in software, cohesion. Cohesion–the principle that “things that belong together should be kept together”–makes code easier to understand, debug, and test.
01 Nov 2010
Written with Tim Ottinger for PragPub. Our well-meaning agile coach’s maturity model was based, either deliberately or subconsciously, on Shuhari, a Japanese martial arts concept involving three stages of mastery: “first learn, then detach, and finally transcend.”
01 Oct 2010
Written with Tim Ottinger for PragPub. Tim and I present some stories about dogmatists, cowboys, and authoritarians, demonstrating a few ways that your transition to agile can be derailed.
01 Sep 2010
26 Aug 2009
Published at InformIT, this article is a companion piece to Mike Cohn’s book Succeeding with Agile: Software Development Using Scrum. It takes an automated test example from the book and demonstrates how to enhance it to act as clearer documentation on the system’s capabilities.
18 Sep 2008
Written for Developer.com. The design patterns book lists 23 design patterns, but that’s just the beginning! Many more patterns exist, including the specification pattern, lazy initialization, object pools, and the utility class pattern.
04 Sep 2008
Written for Developer.com. One of the bigger challenges with using design patterns is knowing when to use one pattern over another. The abstract factory creational pattern looks similar to the builder pattern but is used to help solve a different problem.
28 Aug 2008
Written for Developer.com. Your production code isn’t the only place you will find a use for design patterns. The factory method pattern helps you answer a question about how to organize your test classes.
14 Aug 2008
Written for Developer.com. Building applications for the BlackBerry involves a few interesting wrinkles. Explore some of these challenges in building a front end for a new BlackBerry unit testing framework.
24 Jul 2008
Written for Developer.com. What do you do when there’s no effective unit testing framework for your programming environment? Why, build your own, of course! Building a simple unit testing framework for the BlackBerry provides some interesting insights into the BlackBerry programming environment.
09 Jul 2008
Written for Developer.com. Patterns exist for virtually all common programming challenges, even one as simple as “how to traverse a collection of objects.” The iterator pattern provides a consistent solution for something that programmers do daily.
19 Jun 2008
Written for Developer.com. The state pattern can help simplify complex conditional logic by representing individual states as classes, each with its own simple behavior.
05 Jun 2008
Written for Developer.com. Objects talking to each other and no one in control? Messages going all over the place? The mediator pattern can help you control the chaos!
22 May 2008
Written for Developer.com. Many of the design patterns lead a double life–the structure of some patterns are exactly alike, but the intent differs. An interpreter is a composite whose purpose is to support interpretation of a simple grammar.
07 May 2008
Written for Developer.com. The chain of responsibility pattern allows you to emulate a real-life chain of command. In a chain of responsibility, a request moves from handler to handler until someone is able to manage and return it to the client.
21 Apr 2008
Written for Developer.com. A common theme in design patterns is organizing things so as to separate high-level policy from low-level underlying details. The builder pattern does just that, by allowing a single construction policy to be realized by many different implementations.
02 Apr 2008
Written for Developer.com. Like the abstract factory pattern, the prototype pattern helps you adhere to a clean design by moving object creation into a polymorphic hierarchy. When using the prototype pattern, you create objects by making copies of already existing instances.
20 Mar 2008
Written for Developer.com. The singleton pattern is one of the simplest in the catalog of design patterns. Lurking beneath its simplicity is the potential for testing trouble!
05 Mar 2008
Written for Developer.com. Separating interface from implementation is a fundamental object-oriented strategy, one that’s also the essence of the bridge design pattern. You can use the bridge pattern to help solve the more complex problem of separating tangled hierarchies.
06 Feb 2008
Written for Developer.com. Not all design patterns are complex. The adapter pattern provides a simple mechanism for conforming an interface into one that’s more useful for a client application.
28 Jan 2008
Written for Developer.com. Visitor is often viewed as a complex pattern that’s often regarded as difficult and troublesome. But the appropriate use of visitor demonstrates what’s at the heart of good object-oriented design.
10 Jan 2008
Written for Developer.com. The Memento design pattern presents a consistent solution for storing state, allowing you to build undo and redo support in your applications with ease.
03 Jan 2008
Written for Developer.com. Test doubles (aka fakes or mocks) are a great tool that allow for deeper ability to test-drive solutions. The most common way to use test doubles is to pass them via constructors or setters. But there are at least a couple other solutions.
07 Dec 2007
Written for Developer.com. Deriving metrics in an agile software development process can be an integral part of managing and improving execution. As with any tool, metrics used poorly can actually damage a project. A set of guiding principles for agile metrics can keep your team on track.
19 Nov 2007
TDD is a simple discipline: “a minute to learn, a lifetime to master.” This Developer.com article offers a number of nuggets on how to improve your mastery of test-driven development.
29 Oct 2007
A brief article written for Developer.com. Are you focusing on the wrong things? Agile promotes de-emphasizing tools, but as agile grows, tools are becoming more pervasive. Agile centers around iterations, but are you focusing too much on the iteration to the detriment of delivering stories?
10 Oct 2007
This article discusses some supporting ideas for this argument that, in most cases, a good design is also a testable design (and conversely, that an untestable design is not a good design). Hosted at Developer.com.
24 Sep 2007
Written for Developer.com. Should you write tests first (before you write production code), or should you write tests after you build the production code?
04 Sep 2007
Written for Developer.com. Get rid of those pesky “if null” constructs invading and cluttering your code by using the null object pattern!
17 Aug 2007
Written for Developer.com. The observer pattern is an important concept in eliminating dual dependencies.
01 Aug 2007
Written for Developer.com. (The original, official title is Design Patterns: Proxy) The proxy pattern provides a protection layer for your objects by exposing a stand-in to interested clients. I’ll explore one possible use for the proxy pattern in this article.
18 Jul 2007
Written for Developer.com. The decorator pattern gives you the flexibility to wrap special behavior around objects. Unlike inheritance, which gives you the ability to predefine specialized behavior, using the decorator pattern allows you to dynamically attach specialized behavior.
02 Jul 2007
Written for Developer.com. The composite pattern takes advantage of recursion to help produce elegant solutions. This example diverges from the typical examples of the composite pattern.
13 Jun 2007
Written for Developer.com. A simple implementation shows how the strategy pattern can be used to swap in varying algorithms.
29 May 2007
Written for Developer.com. Java takes one more tiny step away from its C legacy with this enhancement to version 6.
14 May 2007
Written for Developer.com. Got millions of objects? The flyweight pattern can help!
10 May 2007
Written for Developer.com. A brief overview of OpenJDK, officially announced at JavaOne, and its implications.
27 Apr 2007
Written for Developer.com. What can we do with duplication? The template method pattern allows us to move common portions of an algorithm to a base class, and leave “holes” to be filled in by derived classes.
13 Apr 2007
Not your usual pattern article. How do we arrive at a command pattern implementation if we’re just test-driving code? Hosted at Developer.com.
03 Apr 2007
There are a few ways to approach writing unit tests for a Java main method. Should you bother? I think so! Hosted at Developer.com.
06 Mar 2007
A simple example of how you can refactor some of your longer methods so that they can read well as “high-level policy.” Hosted at Developer.com. (Hopefully it’s clear from this article’s title that I don’t always have the final say on things like titles and blurbs.)
21 Feb 2007
Written for Developer.com. Object-oriented languages provide great opportunities to isolate complexity in a system. A facade buries an unwieldy interface behind a simplified one.
20 Feb 2007
Hosted at Developer.com. An emphatic viewpoint on the value of comments, in response to an earlier Developer.com article on comments by Mike Gunderloy.
07 Feb 2007
An article written for Developer.com that discusses many of the merits behind pair programming.
18 Jan 2007
An article appearing at Gamelan.com (part of Developer.com) that discusses the class java.util.concurrent.DelayQueue, first available as of Java J2SE 5.0. The DelayQueue provides a thread-safe blocking queue that requires objects to remain in the queue for a minimum period of time.
08 Jan 2007
An article appearing at Developer.com. Twenty-one specific recommendations for pair programming.
15 Dec 2006
Part three of a three part introduction to acceptance testing using FitNesse. Hosted at Developer.com.
12 Dec 2006
An overview of agile software development methodologies. Appears at Developer.com.
01 Dec 2006
Part two of a three part introduction to acceptance testing using FitNesse. Hosted at Developer.com.
22 Nov 2006
Article appearing at Gamelan.com (part of Developer.com). A code-based discussion that demonstrates use of the BlockingQueue class found in Java 5’s concurrency packages.
14 Nov 2006
Part one of a three part introduction to acceptance testing using FitNesse. Hosted at Developer.com.
26 May 2006
In the final installment in the TDD series at Informit, I talk about how TDD enables more rapid development.
Crafting Java with Test-Driven Development, Part 12: TDD at Cassatt: An Interview with Jerry R. Jackson
28 Apr 2006
In the twelfth installment in the TDD series at Informit, I ask Jerry Jackson about his experiences with test-driven development at Cassatt.
21 Apr 2006
In the eleventh installment in the TDD series at Informit, I show how to trigger behavior on mouse clicks without cluttering the view with logic.
14 Apr 2006
In the tenth installment in the TDD series at Informit, I show how test-drive building a simple view, emphasizing the need for heavy refactoring of Swing code.
07 Apr 2006
In the ninth installment in the TDD series at Informit, I show how it’s possible to drive development of a Swing GUI using TDD.
24 Mar 2006
In the eighth installment in the TDD series at Informit, I move the application toward a better design through a series of incremental refactorings. The beautiful part about code is that it’s easily changed, especially if you have tests to be confident about it.
17 Mar 2006
In the seventh installment in the TDD series at Informit, I add support for dealing the rest of a hold ’em hand. I also discuss the practice of adding “todo” reminders in code.
17 Feb 2006
In the fifth installment in the TDD series at Informit, I show how to write tests for exceptional conditions.
10 Feb 2006
In the sixth installment in the TDD series at Informit, I talk about the need to keep tests as refactored as production code, so as to better document class capabilities and keep maintenance costs low.
03 Feb 2006
The fourth installment in the TDD series at Informit ponders a number of ways to test that a deck is shuffled so that cards are dealt in a random order.
27 Jan 2006
The third installment in the TDD series at Informit follows up on the discussion of building a
.equals method by discussing the need (or not) for test-driving a
20 Jan 2006
The second installment in the TDD series at Informit discusses how to drive out the development of a
.equals method using TDD.
13 Jan 2006
The first installment in a new series at Informit. This 13-installment series will introduce and discuss test-driven development (TDD) concepts. The series presents the incremental development of an application to play the poker game of hold ’em. Installments will appear roughly every other week for about six months.
22 Jun 2004
A discussion of the forces that drive the need for mock objects, as well as the design impacts of introducing mocks. This is the peer-reviewed submission to the 2004 Agile Developers Conference. (The original article appears in Jeff’s Blog.)
22 Apr 2004
A brief article written for Gamelan.com (part of Developer.com) that discusses the foreach loop in J2SE 5.0.
12 Apr 2004
The final installment in a series of three articles published in Software Development magazine (now part of Dr. Dobbs) about the changes in J2SE version 5.0. This installment covers the remaining new features, including foreach, autoboxing, varargs, typesafe enum, static import, and metadata.
18 Mar 2004
A very brief article written for Gamelan.com (part of Developer.com) that discusses the Formatter class in Java J2SE 5.0. The Formatter class allows for String formatting similar to printf in C; it depends on the availability of the varargs feature in J2SE 5.0.
12 Mar 2004
The second in a series of three articles published in Software Development magazine (now part of Dr. Dobbs) about the changes in Java J2SE version 5.0. This installment digs deeper into the new generics feature.
11 Mar 2004
A very brief article written for Gamelan.com (part of Developer.com) that overviews the varargs (variable arguments) feature in J2SE 5.0.
10 Feb 2004
The first in a series of three articles published in Software Development magazine (now part of Dr. Dobbs) about the changes in Java J2SE version 5.0. This installment overviews the changes and begins a discussion on the generics feature.
03 Jan 2004
A review of the book Extreme Programming Refactored that once appeared at Amazon.com.
15 Apr 2003
A lead article originally published in (the now defunct) C/C++ Users Journal about how to do test-driven development when working in C. Written with Dr. Robert Koss.
08 Mar 2002
An article published in Software Development magazine (now part of Dr. Dobbs) about using test-driven development in conjunction with GUI development. The article demonstrates an approach using Java and Swing to build a small game.
08 Mar 2002
12 Feb 2002
A solution published in Software Development magazine (now part of Dr. Dobbs) for what I call “simple style.” Three rules, instead of an entire book, to give you a simple approach for ensuring that your code remains highly readable and maintainable.
01 Jan 2001
An article presented at OOPSLA 2001. A simple exposition of how to build code using test-first design. The example produces a class that the author still uses for reading CSV (comma-separated values) files.