Category: Authors

RubyMotion: Ruby for iOS development

RubyMotion is a new (commercial) way to develop apps for iOS, this time with Ruby

RubyMotion is a new (commercial) way to develop apps for iOS, this time with Ruby. So why do I think this is better than the traditional way using ObjectveC or other alternatives?

Advantages to other alternatives

Other alternatives often use a wrapper or a different runtime. The problem is that you have to wait for the library/wrapper vendor to include new APIs when iOS gets a new update. RubyMotion instead has a static compiler which compiles to the same code as ObjectiveC. So you can use the myriads of ObjectiveC libraries or even the interface builder. You can even mix your RubyMotion code with existing ObjectiveC programs. Also the static compilation gives you the performance advantages of real native code so that you don’t suffer from the penalties of using another layer. So you could write your programs like you would in ObjectiveC with the same performance and using the same libraries, then why choose RubyMotion?

Advantages to the traditional way

First: Ruby. The Ruby language has a very nice foundation: everything is an expression. And everything can be evaluated with logic operators (only nil and false is false).
In ObjectiveC you would write:

  cell = tableView.dequeueReusableCellWithIdentifier(reuseId);
  if (!cell) {
    cell = [[TableViewCell alloc] initWithStyle: cellStyle, reuseIdentifier: reuseId]];
  }

whereas in Ruby you can write

cell = tableView.dequeueReusableCellWithIdentifier(@reuse_id)
  || TableViewCell.alloc.initWithStyle(@cell_style, reuseIdentifier:@reuse_id)

As you can see you can use the Cocoa APIs right away. But what excites me even more is the community which builds around RubyMotion. RubyMotion is only some months old but many libraries and even award winning apps have been written. Some libraries wrap so called boiler plate code and make it more pleasant you to use. Other introduce new metaphors which change the way apps are written entirely.
I see a bright future for RubyMotion. It won’t replace ObjectiveC for everyone but it is a great alternative.

A minimal set of skills for software development contractors

You aren’t sure if your developer is professional enough? Here are seven topics you can ask him about to find it out. It’s the minimal skill set a modern developer should use.

“Our company is specialized in providing professional software development for our customers”. That’s a nice statement to inspire your customers with. The only problem with it is: every contractor claims to be professional. You wouldn’t even get a project if you admitted to be “unprofessional”. But how can a customer, mostly unaware of the subtleties in the field of software development, decide if his contractor really works professionally? A lot of money currently spent on projects doomed from the beginning could be saved if the answer was that easy. But there’s a lower limit of skills that have to be present to pass the most minimal litmus test on developer professionality. This blog article gives you an overview about the things you should ask from your next software development contractor.

First a disclaimer: I’ve compiled this list of skills with the best intentions. It is definitely possible to develop software without some or even any of these skills. The development can even be performed in a very professional manner. So the absence of a skill doesn’t reveal an unprofessional contractor without fail. And on the other side, the clear presence of all skills doesn’t lead to glorious projects. The list is a rule of thumb to distinguish the “better” contractor from the “worse”. It’s a starting ground for the inexperienced customer to ask the right questions and get hopefully insightful answers.

Let’s assume you are a customer on the lookout for a suitable software development contractor, maybe a freelancer or a company. You might take this list and just ask your potential developer about every item on it. Listen to their answers and let them show you their implementation of the skill. In my opinion, the last point is the most crucial one: Don’t just talk about it, let them demonstrate their abilities. You won’t be able to differentiate the best from the most trivial implementation at first, but that’s part of the learning process. The thing is: if the developer can readily demonstrate something, chances are he really knows what he is talking about.

The minimal skills

The list is sorted by their direct impact on the overall development quality. This includes the quality perceived by you (the customer), the end user and the next developer who inherits the source code once the original developer bails out. This doesn’t mean that the topics mentioned later are “optional” in the long run.

Source code management system

This tool has many different names: source code management (SCM), revision control system (RCS) and version control system (VCS) are just a few of them. It is used to track the changes in the code over time. With this tool, the developer is able to tell you exactly which change happened when, for what version and by whom. It is even possible to undo the change later on. If your developer mentions specific tool names like Git, Subversion, Perforce or Mercurial, you are mostly settled here. Let him show you a typical sync-edit-commit cycle and try to comprehend what he’s telling you. Most developers love to brag about their sophisticated use of version control abilities.

Issue tracking

An issue or bug tracker is a tool that stores all inquiries, bug reports, wishes and complaints you make. You can compare it to a helpdesk “trouble ticket” system. The issue tracker provides a todo list for the developer and acts as an impartial documentation of your communication with the developer. If you can’t get direct access to the issue tracker on their website, let them demonstrate the usage by playing through a typical scenario like a bug report. At least, the developer should provide you with a list of “resolved” issues for each new version of your software.

Continuous integration

This is a relatively new type of tool, but a very powerful one. It can also be named a “build server” or (less powerful) a “nightly build”. The baseline is that your project will be built by an automated process, as often as possible. In the case of continuous integration, the build happens after each commit to the source code management system (refer to the first entry of this list). Let your developer show you what happens automatically after a commit to the source code management system. Ask him about the “build time” of your project (or other projects). This is the time needed to produce a new version you can try out. If the build time is reasonably low (like a few minutes), ask for a small change to your project and wait for the resulting software.

There is a fair chance that your developer not only talks about “continuous integration”, but also “continuous delivery”. This includes words like “staging”, “build queue”, “test installation”, etc. Great! Let them explain and demonstrate their implementation of “continuous delivery”. You’ll probably be impressed and the developer had another chance to brag.

Verification (a.k.a. Testing)

This is a delicate question: “Will the source code contain automated tests?”. Our industry’s expectancy value for any kind of automated tests in a project is still dangerously near absolute zero. If you get blank stares on that question, that’s not a good sign. It doesn’t really matter too much if the answer contains the words “unit test”, “integration test” or even “acceptance test”. Most important again: Let your developer show you their implementation of automated tests in your (or a similar) project. Make sure the continuous integration server (refer to entry number three) is aware of the tests and runs them on every build. This way, everything that’s secured by tests cannot break without being noticed immediately. You probably won’t have to deal with reappearing bugs in every other version, a symptom known as “regression”.

Your developer might be really enthusiastic about testing. While every developer hour costs your precious money, this is money well spent. Think of it as an insurance against unpredictable behaviour of your software in the future. Over the course of development, you won’t notice these tests directly, as they are used internally for development. Talk to your developer about some form of reporting on the tests. Perhaps a “test coverage” report that accompanies the issue list (refer to the second entry)? Just don’t go overboard here. A low test coverage percentage is still better than no tests.

If your developer states that he is “test driven”, that’s not a psychological condition, but a modern attempt to test really thoroughly. Let him demonstrate you the advantages of this approach by playing through an implementation cycle of a small change to your project. It may foster your confidence in the insurance’s power.

Project documentation

Every software project above the trivial level contains so many details that no human brain is able to remember them all after some time. Your developer needs some place to store vital information about the project other than “in the code” and “in the issue tracker”. A popular choice to implement this requirement is providing a Wiki. You probably already know a Wiki from Wikipedia. Think about a web-based text editing tool with structuring possibilities. If you can’t access the documentation tool yourself, let your developer demonstrate it. Ask about an excerpt of your project documentation, perhaps as a PDF or HTML document. Don’t be too picky about the aesthetics, the main use case is quick and easy information retrieval. Even handwritten project documentation may pass your test, as long as it is stored in one central place.

Source code conventions

Nearly all source code is readable by a machine. But some source code is totally illegible by fellow developers or even the original author. Ask your developer about their code formatting rules. Hopefully, he can provide you with some written rules that are really applied to the code. For most programming languages, there are tools that can check the formatting against certain rules. These programs are called “code inspection tools” and fit like hand in glove with the continuous integration server (refer to the third entry). Some aspects of source code readability cannot be checked by algorithms, like naming or clarity of concepts. Good developers perform regular code reviews where fellow developers discuss the code critically and suggest improvements. The best customers explicitely ask for code reviews, even if they won’t participate in them. You will feel the difference in the produced software on the long run.

Community awareness

Software development is a rapidly advancing profession, with game-changing discoveries every other year. One single developer cannot track all the new tools, concepts and possibilities in his field. He has to rely on a community of like-minded and well-meaning experts that share their knowledge. Ask your developer about his community. What (technical) books did he read recently? What books are known by the whole development team? As a customer, you probably can’t tell right away if the books are worth their paper, but that’s not the main point of the question. Just like with tests, the amount of books read by the average programmer won’t make a very long list. If your development team is consistent enough to share a common literature ground, that’s already worth a lot.

But it’s not just books. Even books are too slow for the advancement! Ask about participation in local technical events, like user groups of the programming language of your project. What about sharing? Does the developer share his experiences and insights? The cheapest way to do that is a weblog (you’re reading one right now). Let him show you his blog. How many articles are published in a reasonable timespan, what’s the feedback? Perhaps he writes articles for a technical magazine or even a book? Now you can ask other developers for their opinion on the published work. You’ve probably found a really professional developer, congratulations.

There is more, much more

This list is in no way exhaustive in regard to what a capable developer uses in concepts, skills and tools. This is meant as the minimal set, with a lot of room for improvement. There are compilations of skills like the Clean Code Developer that go way beyond this list. Ask your developer about his personal field of interest. Hopefully, after he finished bragging and techno-babbling for some time, you’re convinced that your developer is a professional one. You shouldn’t settle for less.

A tale of anti-virus software killing local connectivity

We are developing and running a distributed system which is deployed on-site at our client. Everything was running smoothly for years only some minor hick-ups related to network infrastructure problems occurred over time. Then one day our client told us the scheduled database backups were not working anymore. We immediately checked the database, all installed firewall programs and the like on that Windows 7 server machine. The Postgresql database was running and our local and remote application components were able to connect. Strangely though, neither pgAdmin nor psql or even telnet were able to make a connection locally to the database!! Adding more oddity we did not change or update any part of the system at the time things stopped working. Remote access to the database was working though leaving us even more confused. To sum up the situation:

  • Some applications can connect to the database locally, others cannot
  • Remote access to the database works without problems for all applications, even those that cannot connect locally on the server
  • We did not change any of these applications, neither client side nor server side
  • All firewalls were disabled and the problem persisted over reboots

The explanation

So we talked to our client again and depicted our complete analysis pinning the date of the breakage to a moment when we evidently did not change anything. Suddenly it struck him like lightning when he remembered that there was an automatic update of an anti-virus program. He removed the software from the machine and everything worked again as expected. Even reinstalling the anti-virus program did not break the system again. It was only this misbehaving automatic update somewhere in time that killed some part of our system in a most odd way…

Grails and the query cache

The principle of least astonishment can be violated in the unusual places like using the query cache on a Grails domain class.

Look at the following code:

class Node {
  Node parent
  String name
  Tree tree
}

Tree tree = new Tree()
Node root = new Node(name: 'Root', tree: tree)
root.save()
new Node(name: 'Child', parent: root, tree: tree).save()

What happens when I query all nodes by tree?

List allNodesOfTree = Node.findAllByTree(tree, [cache: true])

Of course you get 2 nodes, but what is the result of:

allNodesOfTree.contains(Node.get(rootId))

It should be true but it isn’t all the time. If you didn’t implement equals and hashCode you get an instance equals that is the same as ==.
Hibernate guarantees that you get the same instance out of a session for the same domain object. (Node.get(rootId) == Node.get(rootId))

But the query cache plays a crucial role here, it saves the ids of the result and calls Node.load(id). There is an important difference between Node.get and Node.load. Node.get always returns an instance of Node which is a real node not a proxy. For this it queries the session context and hits the database when necessary. Node.load on the other hand never hits the database. It returns a proxy and only when the session contains the domain object it returns a real domain object.

So allNodesOfTree returns

  • two proxies when no element is in the session
  • a proxy and a real object when you call Node.get(childId) beforehand
  • two real objects when you call get on both elements first

Deactivating the query cache globally or for this query only, returns two real objects.

A small story about outsourcing

A true story about why it isn’t always cheaper to produce more cost-effective. And a story about a process that wasn’t tailored around human requirements.

Let me tell you a story about human labor and automization, cost efficiency and the result of local optimization. The story itself is true, but nearly all details are changed to protect the innocent.

An opportunity

Once, there was a company that produced sensoric equipment with a large portion of electronic circuitry. The whole device was manufactured at the company’s main factory and admired for its outstanding rigidity. Then, one day, the opportunity offered itself to outsource the assembly of the electronics to a country in the asian region. The company boss immediately recognized the business value in this change: The same parts would be produced by the company, shipped to the asian contract manufacturerer, assembled and promptly returned. Then, the company’s engineers will provide the firmware and software for the final product. By outsourcing the most generic step in the production line, the production costs could be lowered significantly.

A detail

There is one little detail that needs to be told: The sensors relied on some very specific and fragile parts only the company itself could produce. These parts were especially sensible to the atmosphere they were assembled in. A very important aspect of the production process was a special purpose machine that could assemble the parts while sustaining the necessary gas mixture and pressure. Upon closer inspection, one could say that the essence of this product’s secret ingredience weren’t the parts itself, but the specifically tailored production process.

The special purpose machine had to be transferred to the contract manufacturer in asia, otherwise, the sensors could not be assembled. This was a minor inconvenience compared to the large profits that could be realized once the outsourcing was completed.

A success

The machine was transported to the contractor, installed and tested. A special crew of workers of the contractor’s staff was trained to operate the machine properly and within the necessary conditions. After a while, the production line began its work. The first sensors assembled offshore returned home. They all worked as intended. The local engineers couldn’t tell the difference but by looking at the serial number. The company management was pleased, the profitability was increased.

A failure

Everything went well for a while. Then, the local engineers noticed a slightly higher number of faulty sensors. Not long after, the quality assurance reported decreasing performance numbers of the devices. The rigidity of the device, the unique selling point, slowly deteriorated. The company management was worried and established a task force to indentify the root cause for this change to the worse.

A mystery

The task force inspected the reported problems and couldn’t make much sense of the numbers. It wasn’t a problem of whole faulty batches (indicating incidents like transport damage), but also not of individual faulty pieces. Instead, they found that if a piece was faulty, the next few pieces from that series were also faulty. Then, there were long intervals with perfectly good pieces until another group of clearly faulty pieces occurred. Something had to go wrong during the assembly process at the contractor.

A revelation

When the task force arrived in the contractor’s factory and inspected the special purpose machine, they found that the atmosphere regulator was damaged. This automatic part of the machine takes care of the mixture and pressure of the gas in the machine during operation and keeps it in the necessary range by applying or draining specific gas. The contractor didn’t bother to replace the rather expensive part when cheap human labor is readily available. They had hired a worker to perform the atmosphere regulation manually. Some lowly paid worker had to watch the pressure numbers and provide more or less gas, just as needed. This was nearly as good as the automatic regulation and still good enough to produce quality devices.

An explanation

But, the contractor only hired one worker per shift. This worker had to go to the toilet sometimes during the work day. When he was away from the machine, it went along unregulated, soon to be misadjusted to the point of only producing junk. Once the worker returned, he would balance the numbers and bring the machine in the OK state again. This situation occurred periodically, but not too often to taint whole batches. Only during his absence, the series of faulty devices would be produced.

A conclusion

I don’t want to add much moral to this story. Perhaps one thing should be considered when recapitulating: Both the company and the contractor “optimized” their costs locally by making cost efficient decisions that turned out to be expensive in the long run. The company chose between expensive, but controlled local production and cheap outsourced assembly, arguably the most delicate step in the whole production process. The contractor chose between a high one-time investment in an automatism and the low ongoing cost of cheap human labor. Both decisions are comprehensible on their own, but lead to a situation that would never have occurred in the original setting.

Testing C programs using GLib

Writing programs in good old C can be quite refreshing if you use some modern utility library like GLib. It offers a comprehensive set of tools you expect from a modern programming environment like collections, logging, plugin support, thread abstractions, string and date utilities, different parsers, i18n and a lot more. One essential part, especially for agile teams, is onboard too: the unit test framework gtest.

Because of the statically compiled nature of C testing involves a bit more work than in Java or modern scripting environments. Usually you have to perform these steps:

  1. Write a main program for running the tests. Here you initialize the framework, register the test functions and execute the tests. You may want to build different test programs for larger projects.
  2. Add the test executable to your build system, so that you can compile, link and run it automatically.
  3. Execute the gtester test runner to generate the test results and eventually a XML-file to you in your continuous integration (CI) infrastructure. You may need to convert the XML ouput if you are using Jenkins for example.

A basic test looks quite simple, see the code below:

#include <glib.h>
#include "computations.h"

void computationTest(void)
{
    g_assert_cmpint(1234, ==, compute(1, 1));
}

int main(int argc, char** argv)
{
    g_test_init(&argc, &argv, NULL);
    g_test_add_func("/package_name/unit", computationTest);
    return g_test_run();
}

To run the test and produce the xml-output you simply execute the test runner gtester like so:

gtester build_dir/computation_tests --keep-going -o=testresults.xml

GTester unfortunately produces a result file which is incompatible with Jenkins’ test result reporting. Fortunately R. Tyler Croy has put together an XSL script that you can use to convert the results using

xsltproc -o junit-testresults.xml tools/gtester.xsl testresults.xml

That way you get relatively easy to use unit tests working on your code and nice some CI integration for your modern C language projects.

Update:

Recent gtester run the test binary multiple times if there are failing tests. To get a report of all (passing and failing) tests you may want to use my modified gtester.xsl script.

Testing antipatterns

Some testing anti patterns found in everyday code.

Catch all

try {
  callFailingMethod()
  fail()
} catch (Exception e) {
}

Problems:
When you look at the test code you cannot see which type of exception is thrown. First it is better for clarity to document which type is thrown and second any bugs in the called code who throw unintended exceptions are swallowed here.

Better:

try {
  callFailingMethod()
  fail()
} catch (ParseException e) {
}

Problems:
If it fails you don’t see why: so always use a message for fail.

Better:

try {
  callFailingMethod()
  fail('ParseException expected')
} catch (ParseException e) {
}

Problems:
If an exception is thrown, you don’t assert that it is the expected exception, so test for the exception message.

Solution:

try {
  callFailingMethod()
  fail('ParseException expected')
} catch (ParseException e) {
  assertEquals("Invalid character at line 2", e.getMessage())
}

Using assert

assert isOdd(3)

Problems:
If you do not enable assertions on the JVM (by passing -ea) this line does nothing and the test passes fine every time.

Better:

assertTrue(isOdd(3))

Problems:
If assertTrue or assertFalse fails, you just get a generic error message, better use a message which communicates the error/

Solution:

assertTrue("3 should be odd", isOdd(3))

AssertTrue instead of assertEquals

  assertTrue('Expected: 1+2 = 3', sum(1, 2) == 3)

Problems:
You don’t see the actual value here, you could include it in the message, but there is an assertion for that: assertEquals

Solution:

  assertEquals(3, sum(1, 2))

Conditional logic in tests

if (isOdd(value)) {
  assertEquals(5, calculate(value)) 
} else {
  assertEquals(6, calculate(value)) 
}

Problems:
Can you look at the test source code and tell me which branch is used? If only one is used all the time, erase the other. If both are used, first make the test deterministic and use two tests, one for each branch.

Summary of the Schneide Dev Brunch at 2012-07-15

If you couldn’t attend the Schneide Dev Brunch in July 2012, here are the main topics we discussed neatly summarized.

Two weeks ago, we held another Schneide Dev Brunch. The Dev Brunch is a regular brunch on a sunday, only that all attendees want to talk about software development and various other topics. If you bring a software-related topic along with your food, everyone has something to share. The brunch was so well attended that we had trouble to all find a chair and fit at the table. There were quite some new participants, so the introductory round was necessary again. Let’s have a look at the main topics we discussed:

Choosing Google Web Toolkit

If you start the development of a new web application today, there are many frameworks to call to aid. Most of them will not lend a hand, but mostly stand in the way. In a short presentation, we learnt about the arguments in favor and against the use of the Google Web Toolkit for the development of a highly customizable web application. The two most important aspects were that GWT enables desktop-like “real” (as opposed to “web”) development but still provides enough hooks to embrace the web-only developers.

Spock Framework

The Spock testing framework tries to bring natural and expressive syntax back to testing. It mixes the best of most current testing and specification frameworks together in a groovy-based domain specific language. The first contact with Spock of one of our attendees was very pleasant. The framework provides opiniated default tools for most modern testing aspects (e.g. mocking), but is extremely integrative with all current testing libraries. The take-away of this topic was: Try Spock for your next adventures in testing.

Schneide job offer

We from the Softwareschneiderei host the Dev Brunch for nearly six years now. In all these years, we grew slowly without the need to announce open job offers. Now is the time where even we have to insert a little bit of advertising into the brunch: we are hiring. Enough said.

SWT UI-based tests

The Standard Widget Toolkit is the graphical foundation of the Eclipse platform. It’s a bit dated (like most Java-based UI toolkits) and doesn’t really embrace automatic UI-based tests. There is SWTBot, but it doesn’t provide the power of a tool like FEST-Swing. We discussed the situation, but couldn’t offer much help.

Decorator pattern

Another question for discussion was the usage of the classic decorator design pattern in a rather twisted use case. Without going into much detail, the best option would have been the use of Mixins, but the environment (Java) doesn’t provide them. It was an interesting discussion with lots of different solution attempts. We didn’t find the definitive answer, but there was some good inspiration in the train of thoughts.

The programming language Go

One guest offered us a quick overview over the new programming language Go, developed by Google. To sum up a few aspects that were mentioned, Go is compiled to native code, doesn’t offer type inheritance but compile-time interface binding (if it matches, it binds) and so-called goroutines. The latter are slightly improved coroutines. The communication between objects is mostly done with channels, a very flexible event notification system. The feature with the most raised eyebrows was the visibility modifier: capitalization. If your name begins with a capital letter, it is exported. You can quickly learn the basics of the language with the web-based “Tour of Go”.

Summary of Java Forum Stuttgart

One attendee summed up his impressions and experiences with this year’s Java Forum Stuttgart, a local Java-based conference. The day was worthwile and informative, but some basic pieces went missing. For example, you weren’t provided with a notepad and a pen and had to go on a hunt at the exhibitor booths. The single extraordinary talk that you’ll remember for years didn’t happen, either. Most visited talks were solid, but not outstanding. Most noteworthy tools this year were Gerrit and Sonar.

Data loses its location

A final aspect for open discussion was the fact that stored data loses its location. With all modern web- or cloud-based services, the notion of a “storage medium” begins to lose meaning. And with the fast mobile internet access, you won’t have to reside at a specific location to access all your data. For the next generations of computer users (read: kids), data will behave like the notorious aether: always there, never affixable.

Epilogue

As usual, the Dev Brunch contained a lot more chatter and talk than listed here. The high number of attendees makes for an unique experience every time. We are looking forward to the next Dev Brunch at the Softwareschneiderei. And as always, we are open for guests and future regulars. Just drop us a notice and we’ll invite you over next time.

Building Windows C++ Projects with CMake and Jenkins

An short and easy way to build Windows C++ Software with CMake in Jenkins (with the restriction to support Visual Studio 8).

The C++ programming environment where I feel most comfortable is GCC/Linux (lately with some clang here and there). In terms of build systems I use cmake whenever possible. This environment also makes it easy to use Jenkins as CI server and RPM for deployment and distribution tasks.

So when presented with the task to set up a C++ windows project in Jenkins I tried to do it the same way as much as possible.

The Goal:

A Jenkins job should be set up that builds a windows c++ project on a Windows 7 build slave. For reasons that I will not get into here, compatibility with Visual Studio 8 is required.

The first step was to download and install the correct Windows SDK. This provides all that is needed to build C++ stuff under windows.

Then, after installation of cmake, the first naive try looked like this (in an “execute Windows Batch file” build step)

cmake . -DCMAKE_BUILD_TYPE=Release

This cannot work of course, because cmake will not find compilers and stuff.

Problem: Build Environment

When I do cmake builds manually, i.e. not in Jenkins, I open the Visual Studio 2005 Command Prompt which is a normal windows command shell with all environment variables set. So I tried to do that in Jenkins, too:

call “c:\Program Files\Microsoft SDKs\Windows\v6.0\Bin\SetEnv.Cmd” /Release /x86

cmake . -DCMAKE_BUILD_TYPE=Release

This also did not work and even worse, produced strange (to me, at least) error messages like:

‘Cmd’ is not recognized as an internal or external command, operable program or batch file.

The system cannot find the batch label specified – Set_x86

After some digging, I found the solution: a feature of windows batch programming called delayed expansion, which has to be enabled for SetEnv.Cmd to work correctly.

Solution: SetEnv.cmd and delayed expansion

setlocal enabledelayedexpansion

call “c:\Program Files\Microsoft SDKs\Windows\v6.0\Bin\SetEnv.Cmd” /Release /x86

cmake . -DCMAKE_BUILD_TYPE=Release

nmake

Yes! With this little trick it worked perfectly. And feels almost as with GCC/CMake under Linux:  nice, short and easy.

Better diagnostics in TDD

Automated tests gain more and more popularity in our field and our company. Avoiding being slowed down by tests becomes crucial. Steve Freeman has a nice talk on infoq.com with many advices for maintaining the benefits of automated testing without producing too much drag. One seldomly discussed topic is test diagnostics and immediately caught our attention. In short your aim is to produce as meaningful messages as possible for failing tests. This leads to the extended TDD cycle depicted below.

There are several techniques to improve the diagnostics of failing tests. Here is a short list of the most important ones:

  • Using assertion messages to make clear what exactly failed
  • Using “named objects” where you essentially just override the toString()-method of some type in your tests to provide meaning for the checked value 
    Date startDate = new Date(1000L) {
    @Override
    public String toString() {
        return "startDate";
    }
};
  • Using “tracer objects” by giving names to mocks/collaborators in the test, e.g. in Mockito-syntax: 
    EventManager em1 = mock(EventManager.class, "Gavin");
EventManager em2 = mock(EventManager.class, "Frank");
// do something with them

Conclusion

By applying the extended TDD-cycle you can drastically reduce guessing of what went wrong and find regressions much faster without using debug messages or the debugger itself.