Highlights from ISTA and GTAC 2016

Posted by Alexander Todorov on Wed 30 November 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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