Articles by Alexander Todorov

Overridden let() causes segfault with RSpec

Last week Anton asked me to take a look at one of his RSpec test suites. He was able to consistently reproduce a segfault which looked like this:

/home/atodorov/.rbenv/versions/2.3.2/lib/ruby/gems/2.3.0/gems/rspec-core-3.5.4/lib/rspec/core/runner.rb:113: [BUG] vm_call_cfunc - cfp consistency error
ruby 2.3.2p217 (2016-11-15 revision 56796) [x86_64-linux]

-- Control frame information -----------------------------------------------
c:0013 p:---- s:0048 e:000047 CFUNC  :map
c:0012 p:0011 s:0045 e:000044 BLOCK  /home/atodorov/.rbenv/versions/2.3.2/lib/ruby/gems/2.3.0/gems/rspec-core-3.5.4/lib/rspec/core/runner.rb:113
c:0011 p:0035 s:0043 e:000042 METHOD /home/atodorov/.rbenv/versions/2.3.2/lib/ruby/gems/2.3.0/gems/rspec-core-3.5.4/lib/rspec/core/configuration.rb:1835
c:0010 p:0011 s:0040 e:000039 BLOCK  /home/atodorov/.rbenv/versions/2.3.2/lib/ruby/gems/2.3.0/gems/rspec-core-3.5.4/lib/rspec/core/runner.rb:112
c:0009 p:0018 s:0037 e:000036 METHOD /home/atodorov/.rbenv/versions/2.3.2/lib/ruby/gems/2.3.0/gems/rspec-core-3.5.4/lib/rspec/core/reporter.rb:77
c:0008 p:0022 s:0033 e:000032 METHOD /home/atodorov/.rbenv/versions/2.3.2/lib/ruby/gems/2.3.0/gems/rspec-core-3.5.4/lib/rspec/core/runner.rb:111
c:0007 p:0025 s:0028 e:000027 METHOD /home/atodorov/.rbenv/versions/2.3.2/lib/ruby/gems/2.3.0/gems/rspec-core-3.5.4/lib/rspec/core/runner.rb:87
c:0006 p:0085 s:0023 e:000022 METHOD /home/atodorov/.rbenv/versions/2.3.2/lib/ruby/gems/2.3.0/gems/rspec-core-3.5.4/lib/rspec/core/runner.rb:71
c:0005 p:0026 s:0016 e:000015 METHOD /home/atodorov/.rbenv/versions/2.3.2/lib/ruby/gems/2.3.0/gems/rspec-core-3.5.4/lib/rspec/core/runner.rb:45
c:0004 p:0025 s:0012 e:000011 TOP    /home/atodorov/.rbenv/versions/2.3.2/lib/ruby/gems/2.3.0/gems/rspec-core-3.5.4/exe/rspec:4 [FINISH]
c:0003 p:---- s:0010 e:000009 CFUNC  :load
c:0002 p:0136 s:0006 E:001e10 EVAL   /home/atodorov/.rbenv/versions/2.3.2/bin/rspec:22 [FINISH]
c:0001 p:0000 s:0002 E:0000a0 (none) [FINISH]

Googling for vm_call_cfunc - cfp consistency error yields Ruby #10460. Comments on the bug and particularly this one point towards the error:

> Ruby is trying to be nice about reporting the error; but in the end,
> your code is still broken if it overflows stack.

Somewhere in the test suite was a piece of code that was overflowing the stack. It was somewhere along the lines of

describe '#active_client_for_user' do
  context 'matching an existing user' do
    it_behaves_like 'manager authentication' do
      include_examples 'active client for user with existing user'

Considering the examples in the bug I started looking for patterns where a variable was defined and later redefined, possibly circling back to the previous definition. Expanding the shared examples by hand transformed the code into

describe '#active_client_for_user' do
  context 'matching an existing user' do
    let(:user) { create(:user, :manager) }
    let!(:api_user_authentication) { create(:user_authentication, user: user) }
    let(:user) { api_user_authentication.user }

    context 'with an `active_assigned_client`' do
      ... skip ...

    ... skip ...

Line 5. overrode line 3. When line 4. was executed first because of lazy execution and the call execution path became: 4-5-4-5-4-5 ... NOTE: I think we need a warning about that in RuboCop, see RuboCop #3769. The fix however is a no brainer:

-  let(:user) { create(:user, :manager) }
-  let!(:api_user_authentication) { create(:user_authentication, user: user) }
+  let(:manager) { create(:user, :manager) }
+  let!(:api_user_authentication) { create(:user_authentication, user: manager) }

Thanks for reading and happy testing.

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Highlights from ISTA and GTAC 2016

ISTA 2016

Another two weeks have passed and I'm blogging about another 2 conferences. This year both Innovations in Software Technologies and Automation and Google Test Automation Conference happened on the same day. I was attending ISTA in Sofia during the day and watching the live stream of GTAC during the evenings. Here are some of the things that reflected on me:

  • How can I build my software in order to make this a perfect day for the user ?
  • People are not the problem which causes bad software to exist. When designing software focus on what people need not on what technology is forcing them to do;
  • You need to have blind trust in the people you work with because all the times projects look like they are not going to work until the very end!
  • It's good to have diverse set of characters in the company and not homogenize people;
  • Team performance grows over time. Effective teams minimize time waste during bad periods. They (have and) extract value from conflicts!
  • One-on-one meetings are usually like status reports which is bad. Both parties should bring their own issues to the table;
  • To grow an effective team members need to do things together. For example pair programming, writing test scenarios, etc;
  • When teams don't take actions after retrospective meetings it is usually a sign of missing foundational trust;
  • QA engineers need to be present at every step of the software development life-cycle! This is something I teach my students and have been confirmed by many friends in the industry;
  • Agile is all about data, even when it comes to testing and quality. We need to decompose and measure iteratively;
  • Agile is also about really skillful people. One way to boost your skills is to adopt the T-shaped specialist model;
  • In agile iterative work and continuous delivery is king so QA engineers need to focus even more on visualization (I will also add documentation), refactoring and code reviews;
  • Agile teams need to give opportunities to team members for taking risk and taking ownership of their actions in the gray zone (e.g. actions which isn't clear who should be doing).

In the brave new world of micro services end to end testing is no more! We test each level in isolation but keep stable contracts/APIs between levels. That way we can reduce the test burden and still guarantee an acceptable level of risk. This change in software architecture (monolithic vs. micro) leads to change in technologies (one framework/language vs. what's best for the task) which in turn leads to changes in testing approach and testing tools. This ultimately leads to changing people on the team because they now need different skills than when they were hired! This circles back to the T-shaped specialist model and the fact that QA should be integrated in every step of the way! Thanks to Denitsa Evtimova and Lyudmila Labova for this wisdom and the quote pictured above.

Aneta Petkova talked about monitoring of test results which is a topic very close to my work. Imagine you have your automated test suite but still get failures occasionally. Are these bugs or something else broke ? If they are bugs and you are waiting for them to be fixed do you execute the tests against the still broken build or wait ? If you do, what additional info do you get from these executions vs. how much time do you spend figuring out "oh, that's still not fixed or geez, here's another hidden bug in the code" ?

Her team has modified their test execution framework (what I'd usually call a test runner or even test lab) to have knowledge about issues in JIRA and skip some tests when no meaningful information can be extracted from them. I have to point out that this approach may require a lot of maintenance in environments where you have failures due to infrastructure issues. This idea connects very nicely with the general idea behind this year's GTAC - don't run tests if you don't need to aka smart test execution!

Boris Prikhodskiy shared a very simple rule. Don't execute tests

  • which have 100 % pass rate;
  • during the last month;
  • and have been executed at least 100 times before that!

This is what Unity does for their numerous topic branches and reduces test time with 60-70 percent. All of the test suite is still executed against their trunk branch and PR merge queue branches!

At GTAC there were several presentations about speeding up test execution time. Emanuil Slavov was very practical but the most important thing he said was that a fast test suite is the result of many conscious actions which introduced small improvements over time. His team had assigned themselves the task to iteratively improve their test suite performance and at every step of the way they analyzed the existing bottlenecks and experimented with possible solutions.

The steps in particular are (on a single machine):

  • Execute tests in dedicated environment;
  • Start with empty database, not used by anything else; This also leads to adjustments in your test suite architecture and DB setup procedures;
  • Simulate and stub external dependencies like 3rd party services;
  • Move to containers but beware of slow disk I/O;
  • Run database in memory not on disk because it is a temporary DB anyway;
  • Don't clean test data, just trash the entire DB once you're done;
  • Execute tests in parallel which should be the last thing to do!
  • Equalize workload between parallel threads for optimal performance;
  • Upgrade the hardware (RAM, CPU) aka vertical scaling;
  • Add horizontal scaling (probably with a messaging layer);

John Micco and Atif Memon talked about flaky tests at Google:

  • 84% of the transitions from PASS to FAIL are flakes;
  • Almost 16% of their 3.5 million tests have some level of flakiness;
  • Flaky failures frequently block and delay releases;
  • Google spends between 2% and 16% of their CI compute resources re-running flaky tests;
  • Flakiness insertion speed is comparable to flakiness removal speed!
  • The optimal setting is 2 persons modifying the same source file at the same time. This leads to minimal chance of breaking stuff;
  • Fix or delete flaky tests because you don't get meaningful value out of them.

So Google want to stop a test execution before it is executed if historical data shows that the test has attributes of flakiness. The research they talk about utilizes tons of data collected from Google's CI environment which was the most interesting fact for me. Indeed if we use data to decide which features to build for our customers then why not use data to govern the process of testing? In addition to the video you should read John's post Flaky Tests at Google and How We Mitigate Them.

At the end I'd like to finish with Rahul Gopinath's Code Coverage is a Strong Predictor of Test suite Effectiveness in the Real World. He basically said that code coverage metrics as we know them today are still the best practical indicator of how good a test suite is. He argues that mutation testing is slow and only provides additional 4% to a well designed test suite. This is absolutely the opposite of what Laura Inozemtseva presented last year in her Coverage is Not Strongly Correlated with Test Suite Effectiveness lightning talk. Rahul also made a point about sample size in the two research papers and I had the impression he's saying Laura didn't do a proper academic research.

I'm a heavy contributor to Cosmic Ray, the mutation testing tool for Python and also use mutation testing in my daily job so this is a very interesting topic indeed. I've asked fellow tool authors to have a look at both presentations and share their opinions. I also have an idea about a practical experiment to see if full branch coverage and full mutation coverage will be able to find a known bug in a piece of software I wrote. I will be writing about this experiment next week so stay tuned.

Thanks for reading and happy testing!

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Women In Open Source

OpenFest 2016

It's been 2 weeks after OpenFest 2016 and I've promised to blog about what happened during the Women in Open Source presentation, which is the only single talk I did attend.

The presenters were Jona Azizaj, whom I met at FOSDEM earlier this year, Suela Palushi and Kristi Progri, all 3 from Albania. I've went to OpenFest specifically to meet them and listen to their presentation.

They started by explaining their background and telling us more about their respective communities, Fedora Women, WoMoz, GNOME Outreach and the Open Labs hackerspace in Tirana. The girls gave some stats how many women there are in the larger FOSS community and what some newcomer's first impressions could be.

Did you know that in 2002 1.1% of all FOSS participants were female, while in 2013 that was 11% ? A 10x increase but of them only 1.5% are developers.

The presentation was a nice overview of different opportunities to get involved in open source geared towards women. I've specifically asked and the girls responded how they first came to join open source. In general they've had a good and welcoming community around them which made it natural to join and thrive.

Now comes the sad part. Instead of welcoming and supporting these girls that they've stood up to talk about their experiences the audience did the opposite. In particular Maya Milusheva from Plushie Games made a very passionate claim against the topic women in tech. It went like this:

  • I am a woman
  • I am a good developer
  • I am a mother
  • I am a CEO of a successful IT company
  • when I hire I want the best people for my company and they are men
  • women simply don't have the required tech skills/level of expertise
  • the whole talk about women in open source/diversity is bullshit
  • girls need to sit down on their asses and read more, code more, etc.

In terms of successfullness I think I can compare to Maya. I also have a small child, which I regularly take to conferences with me (the badges above). I also have an IT company which generates a comparable amount of income. I also want to hire the best employees for any given project I'm working on. Sometimes it's happened that to be a woman, sometimes not. The point here however was not about hiring more women per se. It was about giving opportunities in the communities and letting people grow for themselves.

Yes, she has a point but there's something WRONG in coming to listen to a presenter just to tell them they are full of shit! It's very arrogant shouting around and arguing a point about hiring when in fact the entire presentation was not about hiring! It is totally unacceptable, The NY Times writing about apps you develop and behaving like an asshole at public events at the same time!

I've been there, the crowd telling me I'm full of shit when I've been presenting about new technologies. I've been there being told that my ideas will not work in this or that way, while in fact the very idea of trying and considering a completely different technological approach was what counted. And finally I've been there years later when the same ideas and technologies have become mainstream and the same crowd was now talking about them!

After Maya there was another person who grabbed the microphone and continued to talk nonsense. Unfortunately he didn't state his name and I don't know the guy in person. What he said was along the lines of little boys play with robots, little girls play with dolls. They like it this way and that's why girls don't get involved in the technical field. Also if a girl played with robots she will be called a tomboy and generally have a negative attitude towards her.

It's absolutely clear this guy has no idea what he's talking about. Everyone who has small children around them will agree that they are born with equal mental capacity. It is up to the environment, parents, teachers, etc to shape this capacity in a positive way. I've seen children who taught themselves speaking English from YouTube and children the same age barely speaking Bulgarian. I've seen children who are curious about the world and how it works and children who can't wipe their own noses. It's not because they like it that way, it's because of their parents and the environment they live in.

Finally I'd like to respond to this guy (I was specifically motioned at the conference not to respond) with this

I have a 5 year old girl. She likes robots as much as she likes dolls. She works with Linux and is lucky enough to have one of the two OLPCs laptops in Bulgaria. She plays SuperTux and has already found a bug in it (I've reported it). She's been to several Linux and IT conferences as you can see from the picture above. She likes being taken to hackathons and learning about inspiring stuff that students are doing.

Are you telling me that because we have the wrong idea women can't be good at technology she can't become a successful engineer ? Are you telling me to basically scratch the next 10 years of her life and tell her she can't become what she wants ? Because if you do I say FUCK OFF!

Even I as a parent don't have the power to tell my child what they can do or not do, what they can accomplish or not. My job is to show them the various possibilities that exist and guide and support them along they way they want to go! This is what we as society also need to do for everyone else!

To wrap up I will tell you about a psychological experiment we devised with Jona and Suela. I've proposed to find a male and female student in Tirana and have them pose online as somebody from the opposite sex, fake accounts and all. They've proposed having the same person both act as male or female for the purposes of evening out the tech skills difference. The goal is to see how does the tech community react to their contributions and try to measure how much does their gender being known affect their performance! I hope the girls will find a way to perform this experiment together with the university Psychology department and share the results with us.

Btw I will be visiting OSCAL'17 to check up on that so see you in Albania!

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IT Weekend Highlights

IT Weekend

Last weekend I attended the third IT Weekend. It's like a training camp for athletes but for QA engineers. While during the first week the crowd was more in the junior to mid level range now the crowd was more into the senior level range which made for better talks and discussions. The most interesting sessions for me were On-boarding of New Team Members by Nikola Naidenov and Agile Leadership by Bogoi Bogdanov. Here are some of the highlights that I wrote down:

  • On-boarding of new team members is very important. You need to have a plan for their first 6 months at the company. This plan needs to have clearly defined tasks and expectations;
  • When a person becomes productive for their team/company it means they have been on-boarded successfully;
  • A company provided trainer is a good thing but they tend to focus on broader knowledge, they don't cover team specific domain knowledge;
  • Some companies provide both technical and business trainers for their teams;
  • It is very important to get timely feedback when you are the one providing training. However feedback isn't always easy to get and we don't always receive sincere feedback;
  • If the team is swamped with work tasks you need to provide 10-20% of the time for learning and experimenting with new technologies. IMO this is best done by filing tickets in your bug/task tracking system and prioritizing them together with the rest of the tasks;
  • It is also important to have an individual training plan for each team member and review this on a regular basis;
  • We should strive to use unified terminology and jargon as to not confuse people. IMO it is usually the new hires who are likely to get confused because they are not familiar with the history of the terms used;

In an agile environment we calculate productivity using the formula

Productivity = Effort * Competence * Environment * Motivation^2

There are 3 important factors that drive motivation

  • to have a Purpose
  • to feel Autonomy
  • to be able to achieve Mastery in your skills

It is also important to note that autonomy is not the opposite of alignment as depicted by the image below.

Alignment and autonomy

In agile environment control is a function of trust. To be able to trust people we need to give them autonomy, transparency and short feedback loop!

  • Manage for the normal treat exceptions as exceptional;
  • Failure recovery is more important than failure avoidance;
  • Fail fast means learning fast and improving fast.

Thanks for reading and happy testing!

Photo credit: Rayna Stankova

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Animate & Automate

Recently I've attended a presentation by MentorMate where they talked about testing CSS animations ( video in Bulgarian ). The software under test was an ad tech SDK which provides CSS based animations to mobile apps and games. The content is displayed inside a webview and they had to make sure animations were working correctly on different OS and devices.

Analyzing the content (aka getting to know the domain) they figured out in reality there were about 20 basic movements and transformations. So the problem was reduced to "How do we test these 20 basic movements under various OSes and devices" or "How do we verify that basic CSS transformations are supported under different versions and flavors of the OS"?

Their test bed included hand crafted web pages with each basic movement and then several ones with more complex animations (aka integration testing). The idea was to load these pages under different devices and inspect whether or not the animations were visualized properly.

A test script (aka their testing framework) was constantly recording the coordinates of the elements under test to verify that they were really animated. The idea was to use a sample rate of 20ms and expect at lest 20 different changes to the element under test. Coordinates along with color and gradient were recorded and then returned back and analyzed to report a PASS or FAIL result.

This simplistic framework has limitations of course. It is not currently checking the boundaries of where the elements are rendered on the screen. Thus if everything else works as expected this will be a false positive result. On their slides this can be seen at 23:10.

As a side note the entire effort took about 2 days, including research and preparing the test content.

I really like the back to basics approach here and the simplistic framework that MentorMate came up with. Sure it misses some problems but for that particular case it is good enough, easy and fast to implement.

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The Passionate Doer

Passionate violinist

Two weeks ago I visited Startup Factory Ruse and had the opportunity to attend The Passionate Doer – Lessons Learned where Yana Petrova shared her journey with CoKitchen in the past 2 years. The event name comes from The Passionate Programmer book.

A doer is somebody who acts and strives to make changes. When you jump into something new it looks hard and scary at first. With time the important and difficult tasks begin to look like ordinary ones because you gain the experience required for them.

When you are a start-up company you have a limited amount of time and finance to make a break through. Thus it is important to hire the right people, but Yana argues it is more important to quickly dismiss the people who don't fit into your organization. I quite agree with her and the following paragraphs are centered around this idea.

An interesting point Yana makes is about negative reactions and lack of motivation in employees. When a person is lacking motivation they have troubles making logical connections between various tasks and are not able to see the big picture or how their actions or lack thereof affect everything else in the organization. She thinks these are most likely due to problems in our private lives instead of problems at work and as managers we should seek to understand what triggers these negative effects.

Yana believes fatigue makes us vulnerable to negative thoughts so it is best to make important decisions after you've had a good rest. In similar fashion her way to deal with a non-motivated employee is to give them a short break. Then she asks whether or not the employee is ready to return back to work and invest 100% into the job. If not then both parties say good bye to each other. Yana also says that for most problematic employees she'd seen it hasn't been worth it to bring them back and try to improve them.

I've asked Yana if she had some sort of test to keep track of how well a person performs their job. She didn't quite answer but an indicator for under-performance to her is how busy the rest of the team is. Unwillingness to take corrective action, e.g. explore new ways of doing things, acquire more skills or read particular books which will help improve on areas she'd identified, is also a good indicator that the person will have a tendency to under-perform.

Yana says she wouldn't keep an employee who defines their own boundaries and doesn't want to expand them because that person will not go out of their comfort zone. This leaves everyone else tiptoeing around that employee and having to do the job they can't, which puts more stress on the team.

Same approach we should adopt towards customers as well. Get rid of rude and angry customers so that the work flows with less stress.

Yana has been part of many volunteer efforts and her mistake was that she expected everyone to have the same volunteering spirit that she has. In reality it turned out people had trouble managing their own time or lacking the proper communication skills. Not taking responsibility for your actions and not learning from mistakes are other traits she noticed.

At CoKitchen they aim at pairing completely different people with one another so that everyone is able to learn the most from the other person. This is part of their internal mentorship program.

Another interesting book mentioned by a member of the audience was Drive: The Surprising Truth About What Motivates Us. The book reveals the three elements of true motivation:

  • AUTONOMY - the desire to direct our own lives;
  • MASTERY - the urge to get better and better at something that matters;
  • PURPOSE - the yearning to do what we do in the service of something larger than ourselves.

Sounds like an interesting book (from the point of view of the employer) which is definitely going into my reading list.

Sorry if my notes are a bit terse this time, it's been a busy month. I still hope you learned something new from this post. Thanks for reading!

Image credit: Omar Ismail

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Updated MacBook Air Drivers for RHEL 7.3

Today I have re-build the wifi and backlight drivers for MacBook Air against the upcoming Red Hat Enterprise Linux 7.3 kernel. wl-kmod again needed a small patch before it can be compiled. mba6x_bl has been updated to the latest upstream and compiled without errors. The current RPM versions are


and they seem to work fine for me. Let me know if you have any issues after RHEL 7.3 comes out officially.

PS: The bcwc_pcie driver for the video camera appears to be ready for general use, regardless of some issues. No promises here but I'll try to compile that one as well and provide it in my Macbook Air RHEL 7 repository.

PS2: Sometime after Sept 14th I have probably upgraded my system and now it can't detect external displays if the display is not plugged in during boot. I'm seeing the following

# cat /sys/class/drm/card0-DP-1/enabled

which appears to be the same issue reported on the ArchLinux forum. I'm in a hurry to resolve this and any help is welcome.

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The 4 Basic Communication Styles

4 communication styles

The first GEM Conference in Bulgaria took place on Monday and Tuesday. I missed most of the sessions due to other meetings and tasks but managed to attend a workshop on the topic How to harness the power of influence and communication in entrepreneurship by Plamen Popov and Yassar Markos.

3 Fundamentals for Communication

According to Plamen and Yassar there are 3 key fundamentals for any kind of communication:

  • Willingness to pay the price for this communication to happen;
  • Flexibility because we need to try different approaches until we reach the desired person in a way they can understand what we're saying;
  • Integrity because we always need to be consistent in what we deliver to others so that we always match their expectations.

4 Communication Styles

Then there are 4 basic communication styles based on how formal or informal the communication is and how passive or aggressive it is.

  • Director aka dominant style - they exhibit formal and aggressive communication. Key words for them are results, effectiveness, no small talk, to the point. They dislike wasting their time because they always have something better and more interesting to do. This is why people in this group are the worst listeners. They love conflicts and seek ideas and results.

  • Expresser aka promoting style are dominant/aggressive but informal. They are loud, always speak about themselves, they want public attention and to be unique. They forget details but instead are able to grasp the big picture quite easily. They have lots of energy and passion and love to start new projects and don't complete them.

  • Harmonizer aka supportive style - they exhibit informal and passive communication. They love connections and relationships, they use soft language and look after people and team mates. They don't like conflicts and competitive games. People from this style get impressed when you share personal stories and details with them.

  • Thinker aka analytical style people are formal but non-aggressive. They like to know all the facts and always ask lots of questions because they need to understand the big picture. They need time to understand before they can make a decision. In their lives everything has a particular place. They are prone to postponing tasks until they reach perfection (which they never will).

A person typically has one dominant style and a mix of one or two others. I myself am mostly Director and Expresser aka dominant and promoting with a pinch of Thinker. I mostly lack the Harmonizer traits. However it is more important to know what style the person you are talking to is, not what your personal style is.

When judging the style of others take into account where you stand. A person who is strongly formal and aggressive will view a less formal and mild person as the Expresser or Harmonizer style. However to a 3rd party both of these two persons may appear to be dominated by the Director style.

How to Make a Good Presentation

When presenting to a single person or a small group obviously you have to tailor your presentation according to their communication styles. However when presenting before a large and diverse crowd you need to account for all of them in the following order:

  • Capture the Expresser or promoting style by giving them a promise for something cool and interesting. Because they easily forget details and become distracted you can lose them first.

  • Then capture the Director or dominant style by asserting your authority. State your expertise in the field to establish trust. Also sell them the idea for efficiency because this is the value they need to extract from you.

  • Third comes the Harmonizer or supportive style. They seek open people to connect with. Personal stories and struggles are the best way to engage them.

  • Last comes the Thinker or analytical style. They need to know all the information so you have to give them links and materials for further reading. It is also a good idea to give them the ability to ask you questions later (via email, chat, etc) because they will analyze your ideas and come up with more questions on their own.

I have already started to organize my presentations based on the above 4 key points so hopefully you will see me delivering better talks in the future.

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What I Learned from IT Weekend

IT Weekend

Last week I attended the first IT Weekend in Bulgaria. It's like a training camp for athletes but for QA engineers. There were 20 people attending and the format was very friendly and relaxed. The group had members with various levels of experience and technical skills, also different areas they work in. All presentations are on YouTube. Here's a brief of what happened and what I learned.

I had the honor to present in the first slot and gave a quick introduction to mutation testing. This was my first time giving this talk and I'm not entirely happy with how I've presented it. Also mutation testing is touching a lot on unit tests, programming and source code which in some organizations goes to the devel department. I think mutation testing is harder to understand from people not familiar with it than I initially thought. I'm taking note to improve the way I present this topic to the public.

Yavor Donev gave a good overview of Appium and how to use it on Android. The most important question for me was "Is it possible to utilize the same test suite on Android and iOS, given that the environments are different". With this I mean regardless of how much we try to make the same (native) app on both platforms it will end up differently because the platforms are essentially different. For example there is a different number of physical buttons available.

If we assume that both iOS and Android apps follow the same design and use similar workflow then it should be possible to create a test suite which is platform aware and account for the minor differences. We're also adding another layer of complexity by introducing the requirement that both apps stay in sync with each other and account for the quirks of the foreign platform. Depending on your apps and goals this may not be an easy task!

The one thing I didn't like about Appium is that upstream doesn't care much about version compatibility and they tend to break and change stuff arbitrary between releases. That said if it works, don't update it or otherwise be extremely careful.

I also had a nice chat with Yavor on the topic of career change, learning to program and working with people who have very little coding experience. His approach is to develop a higher level test framework on top of Appium which his team mates can use more easily.

Aneta Petkova's Selenium Grid in Unix Environment is a bit out of my domain. However I took one important lesson: regardless of how great your tools are there are minor details which can make or break your day. In her case these are the physical location of the tests (e.g. which Selenium node runs them) and access to shared resources. Turns out WebDriver doesn't give you this information directly and you need to go through hoops to get it. Her solution was to place the test code on the Grid Hub and provide a shared file system.

The bigger lesson is: whenever you have to design an automated test environment (aka test lab) make sure to evaluate your needs beforehand.

The last talk was a guest appearance by Denitsa Evtimova. She is a QA architect with 16 years of experience and presented the QA strategy at Paysafe group. They have a large monolithic system (legacy code) and have adopted a pyramid style approach to testing. Whenever possible tests are brought down to the lowest level (e.g. unit tests) and not repeated on the higher levels. At the top stand manual testing. Teams are small: 3-4 developers and 2-3 QAs. It is the team responsibility to make sure tests are implemented at the lowest possible level. The process is not strictly enforced and the company relies more on self governance in this aspect. Also everyone on the team can contribute additional tests whenever they see something missing. Test (writing) tasks are all logged in JIRA. They are also small so that everything can be completed in the same day.

The second day was more informal. We did a quick exploratory testing exercise and shared opinions on different test tools. Then the group had a discussion about soft skills and how QA engineers can change the perception of developers about the QA profession (especially in teams where there are many manual testers). The key points are:

  • Criticize the software, not the person, e.g. don't blame the person directly;
  • Communicate with concrete facts and data, not emotions and perceptions;
  • Jokes of the type "how many QA engineers are needed to screw a light bulb" are a problem because they lead to underestimation of the job role;
  • Sometimes it is not quite clear (to others) how the QA role contributes to the development of the product and the organization;
  • For a QA it is important to be able to give a non-biased opinion and observations on what is happening with the product/process;
  • A QA person needs to be very calm. They have to be able to listen to everybody (especially developers) and accept their point of view but at the same time also communicate their own point of view.
  • It is important to sit together with developers and observe the problem, brainstorm and propose possible solutions. This also creates a feedback loop where the developer feels empowered because he's part of the process identifying the problem and proposing the best solution;
  • In agile teams it is a good idea to rotate people between developer and QA positions. This will help them better understand the job of others, acquire new skills and also bring fresh thinking to the team;
  • Quality Assurance is an ungrateful job and only people with very calm and methodical thinking (to follow through and write all possible scenarios) are able to excel in this field. On the other hand developer usually think about the happy path scenarios and strive to make their code work as best as they can;
  • By rotating job roles within the team developers will quickly find out that testing is not their field and gain respect towards their QA peers;
  • US managers have the habit of telling "good job" to everyone, even for small and routine tasks. In Bulgaria (and maybe elsewhere) we're not used to this. Instead we're used of being scolded when we do something wrong. If everything is good then we don't receive any recognition;
  • Using the American "good job" is actually a good thing. Team mates will start performing better over time because they will feel their work is valued and not meaningless, they will feel recognized which will boost morale and productivity.

Thanks for reading and happy testing!

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Peter Sabev on Test Automation

the automation snake chart

Last week Peter Sabev gave his talk "On Reporting Bugs: Errors Made and Lessons learned" for (watch in Bulgarian). At the end of the talk there was a quick question how would he approach automation. I have always approached automation in terms of manpower and skills available within the team while he proposed an approach based on return of investment.

Given that you have a team with strong understanding of the software (code) under test and they have good coding skills then start with the hardest test cases first. This way the team will have lots of hard work upfront and there will be some lead time without visible results. However when the hardest/most complex test cases are already automated you will most likely have covered a big portion of the SUT.

On the contrary, when you start with the easiest test cases first then the team will progress gradually and have enough time to get to grips with the SUT. You are also more likely to see more regressions or bugs missed. With this approach every subsequent automated test will be harder to write and more complex than the previous one. This is a good fit for team who don't have strong experience with test automation and/or are unfamiliar with the product.

Peter proposes a different approach. He plots the test cases as dots, based on how much time they take to execute manually and how much time/how hard is it to automate the particular case. Then you start to move from the lower right corner towards the upper left corner in a weaving motion, like a snake,

His argument is that once you automate the test cases which are not very complex but require lots of time to execute by hand then you free up resources within the team. As you progress up the chart the test cases become harder to automate and yield less return of investment because they don't take some much time to execute manually.

For more information about Peter's approach please read his article.

As you can see from the snake chart the team constantly faces test scenarios jumping up and down on the automation hardness scale. Which also means that you need to have the suitable skills within the team. IMO this is best suited for teams where each member has different degree of experience. I'm also in favor of using the snake chart as a tool to distribute automation tasks within the team.

If you'd like to hear more about Peter's and mine views on manual vs. automated testing be sure to follow We are going to host a discussion on October 18th so stay tuned!

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What I Learned from EuRuKo 2016

EuRuKo 2016

As my frequent readers may know I try to summarize all the conferences and events I go to. This year's EuRuKo inspired me to take a different approach and instead of quickly summarizing the event I will try to highlight what I have learned from it! My intention is to use this as a tool to improve my skills and the work I do. It will probably be a long post so here we go.

Let me say that I don't consider myself a Ruby developer although I do write a small amount of Ruby code. I also don't really consider myself a developer although I have a formal degree in software engineering and do my fair share of open source contributions.

Being different and thinking differently has always been helpful to me in Quality Assurance and this time was no exception. Attending a conference I knew nothing about and meeting with people whose job is totally different than mine turned out to be my greatest experience on the conference circuit this year.

Lesson 1

Get out of the comfort zone, meet new people, exchange ideas and learn! The very fact that I am writing this post not following my usual summary style proves this is working.

Very early during the event I started to notice a recurring theme which grew stronger by the minute. The Ruby community is very open and inclusive to newcomers and they seem to be doing a very good job about on-boarding everyone who wants to learn. I already wrote about Ivan Nemitchenko's experience of organizing remote internships and there are also the Rails Girls local communities, the Rails Girls Summer of Code (didn't know about it) and the various local Ruby communities who pitched their cities to host the next EuRuKo. I really loved this feeling of community. In the broader Linux, Python and QA world I have not seen this being so pronounced.

Lesson 2

Open up (the open source) community even more. Make it easier for newcomers to join! Treat them as human and don't expect them to be like yourself. Do teach and mentor both to help newcomers but also to help yourself become better!

This is mostly on par with my community work but I think I can do better. I will take the time to evaluate what I've been doing in the past and identify areas for improvements. I also encourage my readers and students to send me feedback as well.

I've also learned that junior developers can make meaningful contributions to production grade code when they are given the appropriate set of tasks and guidance. Stephanie Nemeth argued that companies should hire (more) enthusiastic career changers as junior developers because they have very strong motivation for success.

Lesson 3

Re-evaluate how we look at junior developers, especially how we examine and hire them and how we on-board them.

Both lessons 2 and 3 are valid in the open source world and even more so in the corporate world.

I also liked the fact that some of the lightning talks were given by people who had no previous experience in Ruby. @TeamJoda2016 talked about what they did and learn throughout the summer and really cracked the room with their "oh and btw we are looking for a job" as their final slide!

Lesson 4

If you are new/inexperienced at something don't be afraid to try it out. Give it the best you've got and see how it goes. Worst case .... well nothing bad really happens, best case you end up doing the best job in your life. That's also been my personal experience with software testing.

Carina C. Zona's Consequences Of An Insightful Algorithm (old video here) dealt with the ethical responsibilities of us as developers and this is becoming more common with deep learning neural networks.

Lesson 5

We’re able to extract remarkably precise intuitions about an individual. But do we have a right to know what they didn’t consent to share, even when they willingly shared the data that leads us there?

Krissy's The HTT(Pancake) Request made a great analogy of consuming APIs with your customer experience when visiting a restaurant.

Lesson 6

Design APIs (software in general) as if that was a physical product where your customers happiness matters. We see this all the time in our daily jobs and we're guilty of doing it as well. Btw at the moment I'm in the middle of huge refactoring of django-chartit which breaks all backwards compatibility. I guess I will have to re-evaluate my design and approach.

By accident I've made good friends with Alex Georgiev and the folks at Fyber. I liked the fact that at the conference they had couple of people working in QA and we managed to have a nice talk about QA vs developers and the transformation between the two. That also touched on the bigger subject of testers not being able to code and testers not being available for hire.

Lesson 7

Driving people to improve their skills (learn to code, write tests, etc) is possible but needs to come from management, needs clear direction and also a little bit of peer pressure.

After all isn't that what an agile team is supposed to be ?

Now being the able to code, not entirely Ruby ignorant QA guy that I am I was immediately offered several positions in London and Berlin (and no I'm still staying in Sofia). As it turned out good QA engineers with good development skills are in greater demand than developers not only in Sofia but all around the world!

Lesson 8

Fellow QA guys, please do learn to program. Dear developers, please try thinking more like a tester the next time you write code (me included).

Hiring a barista and furnishing your company stand with the best coffee machine you can afford while having an ugly hand written sign saying "MAIN CONFERENCE COFFEE ->" is a marketing stunt that I really love. I'm not sure how well that worked for their hiring but it got them visibility. I'm definitely stealing this one!

Lesson 9

Conference coffee sucks. Provide better one and developers will queue at your stand. To a greater extent - research your target and their needs and provide a product that solves their problem.

What we gave back

indeed Monica it is. Here's the secret sauce

My personal contribution back was telling Yammer and Deliveroo about mutation testing and pointing them to the right tools and videos on the subject. I wish them good luck and happy testing.

NOTE: I will be speaking about mutation testing at several different events in Bulgaria in the next 2 months so make sure to find me if you want to chat.

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What Ivan Learned from Organizing Internships

This is a summary of Ivan Nemytchenko's talk at EuRuKo yesterday (slides here). I'm writing this because that was the best talk both in terms of content and visual presentation I saw at the conference and because it is closely related to my work with HackBulgaria.

The short story is that at some point Ivan was mentoring several junior developers and saw the need to scale this effort so he did a call for interns and got back 60 replies.

What an Intern Gets

  1. Projects in their portfolio
  2. Working experience, including team work
  3. Developing an entire product from idea to production

Ivan wanted to find suitable interns who have basic Ruby on Rails knowledge and who could invest a minimum of 20 hours per week of their time so he devised an aptitude test of 3 parts.

Part 1 is developing basic functionality of the product. Part 2 was adding different user types which require different validation logic, etc. Part 3 was adding "purchasing" logic via external APIs. In Part 3 intentionally there was no code review!

The final result was shit! That was the purpose of the test. The reasoning being that there is no right or wrong way to solve the problems he presented to the interns. Instead he wanted to make them think and decide on a solution. Then feel the pain of their decision. Ivan argues that what made us senior developers are these pains we have experienced at some point in our careers, those fuck-ups that we did in some old project. All of them made us better in our job because we could learn from the mistakes we've made and more importantly understand the consequence of our decisions.

The common mistakes Ivan saw were:

  • Ignoring levels of abstraction;
  • Using too many gems without knowing or understanding their limitations;
  • Gems were treated as the only way to solve a problem. More importantly changing this way was out of the question;
  • Interns didn't know about service objects, well even some experienced developers seem to not know that;
  • Business logic was all around the place;
  • Bad naming all around

The next thing Ivan did was a group hangout code review followed by a short lecture about design patterns, a refactoring session and finally cross code review. At the end the product was delivered as expected.

Following these initial efforts Ivan continued (with even more interns, or the next group of them I think) by asking interns to develop internship automatization, that is a means for the system to distribute tasks based on git commits, tags, etc so it can scale. They've added an admin dashboard and started working on an open source alternative to NewRelic (if I got that correctly). He was also able to enlist 2 more mentors to help him.

Problems Ivan found:

  • Not enough mentors and external projects to work on for all of the interns;
  • Treating a project as not real (e.g. not a real world product) is a mistake;
  • A training project has the same management issues that a real product will have and they need to be resolved in pretty much the same way;
  • There was collective irresponsibility from the group of interns. They didn't do what they said they will do;
  • There were communication issues between the interns and the lack of enough mentors was an obvious problem.
  • There was also lack of motivation.

I'd say these are the typical problems one also sees in almost any teams. It doesn't matter if these are teams of students or teams of developers inside some company.

What a Junior Needs

  • A real project to work on;
  • A business context, a reason why something should be done and why it needs to be done in a particular way;
  • Some visible achievement for their portfolio;
  • Team work experience;
  • Whole cycle development experience.

Ivan thinks that the aptitude test worked great because his interns were able to find good jobs afterwards but he will change a few things. There will be even more tests and he will reject unfit/bad interns. He will also do call for mentors not only for interns. And he wants to turn mentors' experience into tests as well.

I particularly like the "business context" item. IMO even seasoned developers need to have this if they are expected to create a great product for their company. We're not just coders but sometimes companies forget that!

I am also wondering how can I apply a similar aptitude test in my work (both mentoring at HackBulgaria and otherwise).

How about Senior Developers

  • They all have routine tasks;
  • and research tasks;
  • Nice to have features and
  • Low priority features;
  • Side project ideas
  • Missing features in their favorite open source projects

Senior developers' tasks and desires will have to align with what a junior needs in order for the mentorship to work. As senior devs we often make a mistake and expect everyone else to think the same way we do and act as fast as we do. Ideally senior developers want to have multiple clones of ourselves to work with! I myself have been guilty of that and trying to change.

In the context of a for-profit company the above findings should be taken into deep consideration if you are about to have interns.

After the talk I was lucky to talk to Ivan and tell him more about the training sessions at HackBulgaria. I also proposed to him the sponsorship model which he hasn't considered. He then made a counter offer: ask interns for high payment upfront and let them recoup that based on their progress towards the end.

I am really happy to have heard this presentation and being able to talk to Ivan in person. I also have my notes about my "QA and Automation 101" training at HackBulgaria and I now have a better idea how to go about organizing and summarizing them (will try to publish that soon).

Last but not least, Ivan works at GitLab and promised to look at an issue I personally have so here it is GitLab #7953 :).

Related reading

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Questers Beer'n'Code Day 2.0

Last weekend I've visited Questers Beer'n'Code Day which was an open air mini-conference held at the terrace of their office. As to organization the only drawback was the summer sun which made it impossible to see anything on the screen. Most speakers were OK with that although they wanted to show some code examples.

I have recorded all talks and they are available in my TECH TALKS YouTube play list. You can also hear me asking some questions from behind the camera. All of the talks are in Bulgarian though, so sorry for my English speaking readers.

The afternoon started with Lidiya Georgieva and her talk about clean code and code smells. I find the topic particularly interesting but she didn't go into more details. She said she had used SonarCube but couldn't recommend any other tools, except for the standard lint style ones. I have been using for all Python based code I've been working on recently and I think it is great.

Another talk I found interesting was by my fellow QA Petar Sabev on reporting bugs. It was more of an entry level talk, but still very informative for both less experienced QAs and other technical folks so I definitely recommend it.

The last one, and most interesting, was Bogoi Bogdanov with Scaling Agile. Despite the name he covered some basics about Agile and what it actually is. Afterwards we've stayed and talked for a good 2 hours more. I definitely would like to hear more from him in the future.

A big thanks to Questers for hosting this event and allowing me to record it. Happy watching.

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Python 2 vs. Python 3 List Sort Causes Bugs

Can sorting a list of values crash your software? Apparently it can and is another example of my Hello World Bugs. Python 3 has simplified the rules for ordering comparisons which changes the behavior of sorting lists when their contents are dictionaries. For example:

Python 2.7.5 (default, Oct 11 2015, 17:47:16) 
[GCC 4.8.3 20140911 (Red Hat 4.8.3-9)] on linux2
>>> [{'a':1}, {'b':2}] < [{'a':1}, {'b':2, 'c':3}]
Python 3.5.1 (default, Apr 27 2016, 04:21:56) 
[GCC 4.8.3 20140911 (Red Hat 4.8.3-9)] on linux
>>> [{'a':1}, {'b':2}] < [{'a':1}, {'b':2, 'c':3}]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unorderable types: dict() < dict()

The problem is that the second elements in both lists have different keys and Python doesn't know how to compare them. In earlier Python versions this has been special cased as described here by Ned Batchelder (the author of Python's coverage tool) but in Python 3 dictionaries have no natural sort order.

In the case of django-chartit (of which I'm now the official maintainer) this bug triggers when you want to plot data from multiple sources (models) on the same chart. In this case the fields coming from each data series are different and the above error is triggered.

I have worked around this in commit 9d9033e by simply disabling an iterator sort but this is sub-optimal and I'm not quite certain what the side effect might be. I suspect you may end up with a chart where the order of values on the X axis isn't the same for the different models, e.g. one graph plotting the data in ascending order the other one in descending.

The trouble also comes from the fact that we're sorting an iterator (a list of fields) by telling Python to use a list of dicts to determine the sort order. In this arrangement there is no way to tell Python how we want to compare our dicts. The only solution I can think about is creating a custom class and implementing a custom __cmp__() method for this data structure!

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PhantomJS 2.1.1 in Ubuntu different from upstream

For some time now I've been hitting PhantomJS #12506 with the latest 2.1.1 version. The problem is supposedly fixed in 2.1.0 but this is not always the case. If you use a .deb package from the latest Ubuntu then the problem still exists, see Ubuntu #1605628.

It turns out the root cause of this, and probably other problems, is the way PhantomJS packages are built. Ubuntu builds the package against their stock Qt5WebKit libraries which leads to

$ ldd usr/lib/phantomjs/phantomjs | grep -i qt => /lib64/ (0x00007f5173ebf000) => /lib64/ (0x00007f5173e4d000) => /lib64/ (0x00007f51737b6000) => /lib64/ (0x00007f5171342000) => /lib64/ (0x00007f5170df8000) => /lib64/ (0x00007f5170c9a000) => /lib64/ (0x00007f517080d000) => /lib64/ (0x00007f516b218000) => /lib64/ (0x00007f516b1d7000) => /lib64/ (0x00007f516b17c000) => /lib64/ (0x00007f516b136000) => /lib64/ (0x00007f5169dad000) => /lib64/ (0x00007f5169999000) => /lib64/ (0x00007f5169978000)

While building from the upstream sources gives

$ ldd /tmp/bin/phantomjs | grep -i qt

If you take a closer look at PhantomJS's sources you will notice there are 3 git submodules in their repository - 3rdparty, qtbase and qtwebkit. Then in their you can clearly see that this local fork of QtWebKit is built first, then the phantomjs binary is built against it.

The problem is that these custom forks include additional patches to make WebKit suitable for Phantom's needs. And these patches are not available in the stock WebKit library that Ubuntu uses.

Yes, that's correct. We need additional functionality that vanilla QtWebKit doesn't have. That's why we use custom version.

Vitaly Slobodin, PhantomJS

At the moment of this writing Vitaly's qtwebkit fork is 28 commits ahead and 39 commits behind qt:dev. I'm surprised Ubuntu's PhantomJS even works.

The solution IMO is to bundle the additional sources into the src.deb package and use the same building procedure as upstream.

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On Python Infinite Loops

How do you write an endless loop without using True, False, number constants and comparison operators in Python ?

I've been working on the mutation test tool Cosmic Ray and discovered that it was missing a boolean replacement operator, that is an operator which will switch True to False and vice versa, so I wrote one. I've also added some tests to Cosmic Ray's test suite and then I hit the infinite loop problem. CR's test suite contains the following code inside a module called

while True:

The test suite executes mutations on and then runs some tests which it expects to fail. During execution one of the mutations is replace break with continue which makes the above loop infinite. The test suite times out after a while and kills the mutation. Everything fails as expected and we're good.

Adding my boolean replacement operator broke this function. All of the other mutations work as expected but then the loop becomes

while False:

When we test this particular mutation there is no infinite loop so Cosmic Ray's test suite doesn't time out like it should and an error is reported.

job ID 25:Outcome.SURVIVED:adam
command: cosmic-ray worker adam boolean_replacer 2 unittest -- tests
--- mutation diff ---
--- a/home/travis/build/MrSenko/cosmic-ray/test_project/
+++ b/home/travis/build/MrSenko/cosmic-ray/test_project/
@@ -32,6 +32,6 @@
     return x
 def trigger_infinite_loop():
-    while True:
+    while False:

So the question becomes how to write the loop condition in such a way that nothing will mutate it but it will still remain true so that when break becomes continue this piece of code will become an infinite loop ? Using True or False constants obviously is a no go. Same goes for numeric constants, e.g. 1 or comparison operators like >, <, is, not, etc. - all of them will be mutated and will break the loop condition.

So I took a look at the docs for truth value testing and discovered my solution:

while object():

I'm creating an object instance here which will not be mutated by any of the existing mutation operators.

Thanks for reading and happy testing!

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Bug in TuxCon Website

TuxCon bug

Here comes July 9th 2016 and the start of TuxCon ... with a bug on their website! The image above is taken during the first talk of the conference. Obviously the count down timer is completely off.

In init.js:100 there is this piece of code

var finalDate = '2016/07/09';

.on('update.countdown', function(event) {
    $(this).html(event.strftime('<span>%D <em>days</em></span>' +
                                '<span>%H <em>hours</em></span>' +
                                '<span>%M <em>minutes</em></span>' +
                                '<span>%S <em>seconds</em></span>'));

It counts backwards and updates the HTML until finalDate is reached. Then the HTML is no longer updated and the default values are shown, which in this case are non zero. A simple patch fixes the problem.

Initialize your variables properly and happy testing!

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Testing the 8-bit computer Puldin

Puldin creators

Last weekend I visited TuxCon in Plovdiv and was very happy to meet and talk to some of the creators of the Puldin computer! On the picture above are (left to right) Dimitar Georgiev - wrote the text editor, Ivo Nenov - BIOS, DOS and core OS developer, Nedyalko Todorov - director of the vendor company and Orlin Shopov - BIOS, DOS, compiler and core OS developer.

Puldin is 100% pure Bulgarian development, while the “Pravetz” brand was copy of Apple ][ (Pravetz 8A, 8C, 8M), Oric (Pravets 8D) and IBM-PC (Pravetz 16). The Puldin computers were build from scratch both hardware and software and were produced in Plovdiv in the late 80s and early 90s. 50000 pieces were made, at least 35000 of them have been exported to Russia and paid for. A typical configuration in a Russian class room consisted of several Puldin computers and a single Pravetz 16. According to Russian sources the last usage of these computers was in 2003 serving as Linux terminals and being maintained without any support from the vendor (b/c it ceased to exist).

Puldin 601

One of the main objectives of Puldin was full compatibility with IBM-PC. At the time IBM had been releasing extensive documentation about how their software and hardware works which has been used by Puldin's creators as their software specs. Despite IBM-PC using faster CPU the Puldin 601 had a comparable performance due to aggressive software and compiler optimizations.

Testing wise the guys used to compare Puldin's functionality with that of IBM-PC. It was a hard requirement to have full compatibility on the file storage layer, that means floppy disks written on Puldin had to be readable on IBM-PC and vice versa. Same goes for programs compiled on Puldin - they had to execute on IBM-PC.

Everything of course had been tested manually and on top of that all the software had to be burned to ROM before you can do anything with it. As you can imagine the testing process had been quite slow and painful compared to today's standards. I've asked the guys if they'd happened to find a bug in IBM-PC which wasn't present in their code but they couldn't remember.

What was interesting for me on the hardware side was the fact that you can plug the computer directly to a cheap TV set and that it's been one of the first computers which could operate on 12V DC, powered directly from a car battery.

Pravetz 8

There was also a fully functional Pravetz 8 with an additional VGA port to connect it to the LCD monitor as well as a SD card reader wired to function as a floppy disk reader (the small black dot behind the joystick).

For those who missed it (and understand Bulgarian) I have a video recording on YouTube. For more info about the history and the hardware please check-out Olimex post on Puldin (in English). For more info on Puldin and Pravetz please visit (in Russian) and (in Bulgarian) using Google translate if need be.

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Testing Data Structures in Pykickstart

When designing automated test cases we often think either about increasing coverage or in terms of testing more use-cases aka behavior scenarios. Both are valid approaches to improve testing and both of them seem to focus around execution control flow (or business logic). However program behavior is sometimes controlled via the contents of its data structures and this is something which is rarely tested.

In this comment Brian C. Lane and Vratislav Podzimek from Red Hat are talking about a data structure which maps Fedora versions to particular implementations of kickstart commands. For example

class RHEL7Handler(BaseHandler):
    version = RHEL7

    commandMap = {
        "auth": commands.authconfig.FC3_Authconfig,
        "authconfig": commands.authconfig.FC3_Authconfig,
        "autopart": commands.autopart.F20_AutoPart,
        "autostep": commands.autostep.FC3_AutoStep,
        "bootloader": commands.bootloader.RHEL7_Bootloader,

In their particular case the Fedora 21 logvol implementation introduced the --profile parameter but in Fedora 22 and Fedora 23 the logvol command mapped to the Fedora 20 implementation and the --profile parameter wasn't available. This is unexpected change in program behavior although the and handlers/ files have 99% and 100% code coverage.

This morning I did some coding and created an automated test for this problem. The test iterates over all command maps. For each command in the map (that is data structure member) we load the module which provides all possible implementations for that command. In the loaded module we search for implementations which have newer versions than what is in the map, but not newer than the current Fedora version under test. With a little bit of pruning the current list of offenses is

ERROR: In `handlers/` the "fcoe" command maps to "F13_Fcoe" while in
`pykickstart.commands.fcoe` there is newer implementation: "RHEL7_Fcoe".

ERROR: In `handlers/` "FcoeData" maps to "F13_FcoeData" while in
`pykickstart.commands.fcoe` there is newer implementation: "RHEL7_FcoeData".

ERROR: In `handlers/` the "user" command maps to "F19_User" while in
`pykickstart.commands.user` there is newer implementation: "F24_User".

ERROR: In `handlers/` the "user" command maps to "F19_User" while in
`pykickstart.commands.user` there is newer implementation: "F24_User".

ERROR: In `handlers/` the "logvol" command maps to "F20_LogVol" while in
`pykickstart.commands.logvol` there is newer implementation: "F21_LogVol".

ERROR: In `handlers/` "LogVolData" maps to "F20_LogVolData" while in
`pykickstart.commands.logvol` there is newer implementation: "F21_LogVolData".

ERROR: In `handlers/` the "network" command maps to "F16_Network" while in
`` there is newer implementation: "F18_Network".

The first two are possibly false negatives or related to the naming conventions used in this module. However the rest appear to be legitimate problems. The user command has introduced the --groups parameter in Fedora 24 (devel is Fedora 25 currently) but the parser will fail to recognize this parameter. The logvol problem is recognized as well since it was never patched. And the Fedora 18 network command implements a new property called hostname which has probably never been available to be used.

You can follow my current work in PR #91 and happy testing your data structures.

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Don't Upgrade Galaxy S5 to Android 6.0

Samsung is shipping out buggy software like a boss, no doubt about it. I've written a bit about their bugs previously. However I didn't expect them to release Android 6.0.1 and render my Galaxy S5 completely useless with respect to the feature I use the most.


Tell me the weather for Brussels

So on Monday I've let Android upgrade to 6.0.1 to be completely surprised that the lockscreen shows the weather report for Brussels, while I'm based in Sofia. I've checked AccuWeather (I did go to Brussels earlier this year) but it displayed only Sofia and Thessaloniki. To get rid of this widget go to Settings -> Lockscreen -> Additional information and turn it off!

I think this weather report comes from GPS/Location based data, which I have turned off by default but did use a while back ago. After turning the widget off and back on it didn't appear on the lockscreen. I suspect they fall back to showing the last good known value when data is missing instead of handling the error properly.

Apps are gone

Some of my installed apps are missing now. So far I've noticed that the Gallery and S Health icons have disappeared from my homescreen. I think S Health came from Samsung's app store but still they shouldn't have removed it silently. Now I wonder what happened to my data.

I don't see why Gallery was removed though. The only way to view pictures is to use the camera app preview functionality which is kind of grose.

Grayscale in powersafe mode is gone

The killer feature on these higher end Galaxy devices is the Powersafe mode and Ultra Powersafe mode. I use them a lot and by default have my phone in Powersafe mode with grayscale colors enabled. It is easier on the eyes and also safes your battery.

NOTE: grayscale colors don't affect some displays but these devices use AMOLED screens which need different amounts of power to display different colors. More black means less power required!

After the upgrade grayscale is no more. There's not even an on/off switch. I've managed to find a workaround though. First you need to enable developer mode by tapping 7 times on About device -> Build number. Then go to Settings -> Developer options, look for the Hardware Accelerated Rendering section and select Simulate Color Space -> Monochromacy! This is a bit ugly hack and doesn't have the convenience of turning colors on/off by tapping the quick Powersafe mode button at the top of the screen!

It looks like Samsung didn't think this upgrade well enough or didn't test it well enough ? In my line of work (installation and upgrade testing) I've rarely seen such a big blunder. Thanks for reading and happy testing!

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