Sounds interesting, +1. Thanks, Eduard On Thu, Mar 15, 2018 at 12:26 PM, Thomas Mortagne <thomas.mortagne@xwiki.com

wrote:

+1

On Thu, Mar 15, 2018 at 9:30 AM, Vincent Massol <vincent@massol.net> wrote:

...

Hi devs,

As part of the STAMP research project, we’ve developed a new tool (Descartes, based on Pitest) to measure the quality of tests. It generates a mutation score for your tests, defining how good the tests are. Technical Descartes performs some extreme mutations on the code under test (e.g. remove content of void methods, return true for methods returning a boolean, etc - See https://github.com/STAMP-project/pitest-descartes). If the test continues to pass then it means it’s not killing the mutant and thus its mutation score decreases.

So in short: * Jacoco/Clover: measure how much of the code is tested * Pitest/Descartes: measure how good the tests are

Both provide a percentage value.

I’m proposing to compute the current mutation scores for xwiki-commons and xwiki-rendering and fail the build when new code is added that reduce the mutation score threshold (exactly the same as our jacoco threshold and strategy).

I consider this is an experiment to push the limit of software engineering a bit further. I don’t know how well it’ll work or not. I propose to do the work and test this for over 2-3 months and see how well it works or not. At that time we can then decide whether it works or not (i.e whether the gains it brings are more important than the problems it causes).

Here’s my +1 to try this out.

Some links: * pitest: http://pitest.org/ * descartes: https://github.com/STAMP-project/pitest-descartes * http://massol.myxwiki.org/xwiki/bin/view/Blog/ControllingTestQuality * http://massol.myxwiki.org/xwiki/bin/view/Blog/MutationTestingDescartes

If you’re curious, you can see a screenshot of a mutation score report at http://massol.myxwiki.org/xwiki/bin/download/Blog/ MutationTestingDescartes/report.png

Please cast your votes.

Thanks -Vincent

-- Thomas Mortagne

+1 Thanks, Marius On Thu, Mar 15, 2018 at 12:49 PM, Ecaterina Moraru (Valica) < valicac@gmail.com> wrote:

+1

Thanks, Caty

On Thu, Mar 15, 2018 at 12:48 PM, Eduard Moraru <enygma2002@gmail.com> wrote:

...

Sounds interesting, +1.

Thanks, Eduard

On Thu, Mar 15, 2018 at 12:26 PM, Thomas Mortagne < thomas.mortagne@xwiki.com

...

wrote:

...

+1

On Thu, Mar 15, 2018 at 9:30 AM, Vincent Massol <vincent@massol.net> wrote:

...

Hi devs,

As part of the STAMP research project, we’ve developed a new tool (Descartes, based on Pitest) to measure the quality of tests. It generates a mutation score for your tests, defining how good the tests are. Technical Descartes performs some extreme mutations on the code under test (e.g. remove content of void methods, return true for methods returning a boolean, etc - See https://github.com/STAMP-project/pitest-descartes). If the test continues to pass then it means it’s not killing the mutant and thus its mutation score decreases.

So in short: * Jacoco/Clover: measure how much of the code is tested * Pitest/Descartes: measure how good the tests are

Both provide a percentage value.

I’m proposing to compute the current mutation scores for xwiki-commons and xwiki-rendering and fail the build when new code is added that reduce the mutation score threshold (exactly the same as our jacoco threshold and strategy).

I consider this is an experiment to push the limit of software engineering a bit further. I don’t know how well it’ll work or not. I propose to do the work and test this for over 2-3 months and see how well it works or not. At that time we can then decide whether it works or not (i.e whether the gains it brings are more important than the problems it causes).

Here’s my +1 to try this out.

Some links: * pitest: http://pitest.org/ * descartes: https://github.com/STAMP-project/pitest-descartes * http://massol.myxwiki.org/xwiki/bin/view/Blog/ ControllingTestQuality * http://massol.myxwiki.org/xwiki/bin/view/Blog/ MutationTestingDescartes

If you’re curious, you can see a screenshot of a mutation score report at http://massol.myxwiki.org/xwiki/bin/download/Blog/ MutationTestingDescartes/report.png

Please cast your votes.

Thanks -Vincent

-- Thomas Mortagne

On 27 Mar 2018, at 19:32, Vincent Massol <vincent@massol.net> wrote:

FYI I’ve implemented it locally for all modules of xwiki-commons and did some build time measurements:

* With pitest/descartes: 37:16 minutes * Without pitest/descartes 5:10 minutes

Actually I was able to reduce the time to 15:12 minutes with configuring pitest with 4 threads. Thanks -Vincent

So that’s a pretty important hit….

So I think one strategy could be to not run pitest/descartes by default in the quality profile (i.e. have it off by default with <xwiki.pitest.skip>true</xwiki.pitest.skip>) and run it on the CI, from time to time, like once per day for example, or once per week.

Small issue: I need to find/test a way to run a crontab type of job in a Jenkins pipeline script. I know how to do in theory but I need to test it and verify it works. I still have some doubts ATM...

WDYT?

Thanks -Vincent

...

On 15 Mar 2018, at 09:30, Vincent Massol <vincent@massol.net> wrote:

Hi devs,

As part of the STAMP research project, we’ve developed a new tool (Descartes, based on Pitest) to measure the quality of tests. It generates a mutation score for your tests, defining how good the tests are. Technical Descartes performs some extreme mutations on the code under test (e.g. remove content of void methods, return true for methods returning a boolean, etc - See https://github.com/STAMP-project/pitest-descartes). If the test continues to pass then it means it’s not killing the mutant and thus its mutation score decreases.

So in short: * Jacoco/Clover: measure how much of the code is tested * Pitest/Descartes: measure how good the tests are

Both provide a percentage value.

I’m proposing to compute the current mutation scores for xwiki-commons and xwiki-rendering and fail the build when new code is added that reduce the mutation score threshold (exactly the same as our jacoco threshold and strategy).

I consider this is an experiment to push the limit of software engineering a bit further. I don’t know how well it’ll work or not. I propose to do the work and test this for over 2-3 months and see how well it works or not. At that time we can then decide whether it works or not (i.e whether the gains it brings are more important than the problems it causes).

Here’s my +1 to try this out.

Some links: * pitest: http://pitest.org/ * descartes: https://github.com/STAMP-project/pitest-descartes * http://massol.myxwiki.org/xwiki/bin/view/Blog/ControllingTestQuality * http://massol.myxwiki.org/xwiki/bin/view/Blog/MutationTestingDescartes

If you’re curious, you can see a screenshot of a mutation score report at http://massol.myxwiki.org/xwiki/bin/download/Blog/MutationTestingDescartes/r...

Please cast your votes.

Thanks -Vincent

On Wed, Mar 28, 2018 at 1:25 PM, Vincent Massol <vincent@massol.net> wrote:

If you’re curious I’ve also added some more information at https://github.com/STAMP-project/pitest-descartes/issues/54

ATM, and even with a time of “only” 10mn to run pitest/descartes on xwiki-commons, it’s still too much IMO so I’ll work on turning it off by default but having a job to run it on the CI.

Sounds good. I agree that we can't enable it all the time given the time lost.

Let me know if you have remarks.

Thanks -Vincent

...

On 27 Mar 2018, at 20:09, Vincent Massol <vincent@massol.net> wrote:

...

On 27 Mar 2018, at 19:32, Vincent Massol <vincent@massol.net> wrote:

FYI I’ve implemented it locally for all modules of xwiki-commons and did some build time measurements:

* With pitest/descartes: 37:16 minutes * Without pitest/descartes 5:10 minutes

Actually I was able to reduce the time to 15:12 minutes with configuring pitest with 4 threads.

Thanks -Vincent

...

So that’s a pretty important hit….

So I think one strategy could be to not run pitest/descartes by default in the quality profile (i.e. have it off by default with <xwiki.pitest.skip>true</xwiki.pitest.skip>) and run it on the CI, from time to time, like once per day for example, or once per week.

Small issue: I need to find/test a way to run a crontab type of job in a Jenkins pipeline script. I know how to do in theory but I need to test it and verify it works. I still have some doubts ATM...

WDYT?

Thanks -Vincent

...

On 15 Mar 2018, at 09:30, Vincent Massol <vincent@massol.net> wrote:

Hi devs,

As part of the STAMP research project, we’ve developed a new tool (Descartes, based on Pitest) to measure the quality of tests. It generates a mutation score for your tests, defining how good the tests are. Technical Descartes performs some extreme mutations on the code under test (e.g. remove content of void methods, return true for methods returning a boolean, etc - See https://github.com/STAMP-project/pitest-descartes). If the test continues to pass then it means it’s not killing the mutant and thus its mutation score decreases.

So in short: * Jacoco/Clover: measure how much of the code is tested * Pitest/Descartes: measure how good the tests are

Both provide a percentage value.

I’m proposing to compute the current mutation scores for xwiki-commons and xwiki-rendering and fail the build when new code is added that reduce the mutation score threshold (exactly the same as our jacoco threshold and strategy).

I consider this is an experiment to push the limit of software engineering a bit further. I don’t know how well it’ll work or not. I propose to do the work and test this for over 2-3 months and see how well it works or not. At that time we can then decide whether it works or not (i.e whether the gains it brings are more important than the problems it causes).

Here’s my +1 to try this out.

Some links: * pitest: http://pitest.org/ * descartes: https://github.com/STAMP-project/pitest-descartes * http://massol.myxwiki.org/xwiki/bin/view/Blog/ControllingTestQuality * http://massol.myxwiki.org/xwiki/bin/view/Blog/MutationTestingDescartes

If you’re curious, you can see a screenshot of a mutation score report at http://massol.myxwiki.org/xwiki/bin/download/Blog/MutationTestingDescartes/r...

Please cast your votes.

Thanks -Vincent

-- Thomas Mortagne

Note: Now that this is done for xwiki-commons, I’d like to also do that for xwiki-rendering when I get the time. Thanks -Vincent

On 4 Apr 2018, at 16:14, Vincent Massol <vincent@massol.net> wrote:

FYI I’ve now committed this on issue https://jira.xwiki.org/browse/XCOMMONS-1385 for xwiki-commons.

And I’ve created an adhoc job at http://ci.xwiki.org/job/xwiki-commons_pitest/ which executes PIT/Descartes (to be moved to our Jenkins pipeline later on).

Let’s now make sure we fix the build when this job breaks and verify if the strategy works or not!

Thanks -Vincent

...

On 15 Mar 2018, at 09:30, Vincent Massol <vincent@massol.net> wrote:

Hi devs,

As part of the STAMP research project, we’ve developed a new tool (Descartes, based on Pitest) to measure the quality of tests. It generates a mutation score for your tests, defining how good the tests are. Technical Descartes performs some extreme mutations on the code under test (e.g. remove content of void methods, return true for methods returning a boolean, etc - See https://github.com/STAMP-project/pitest-descartes). If the test continues to pass then it means it’s not killing the mutant and thus its mutation score decreases.

So in short: * Jacoco/Clover: measure how much of the code is tested * Pitest/Descartes: measure how good the tests are

Both provide a percentage value.

I’m proposing to compute the current mutation scores for xwiki-commons and xwiki-rendering and fail the build when new code is added that reduce the mutation score threshold (exactly the same as our jacoco threshold and strategy).

I consider this is an experiment to push the limit of software engineering a bit further. I don’t know how well it’ll work or not. I propose to do the work and test this for over 2-3 months and see how well it works or not. At that time we can then decide whether it works or not (i.e whether the gains it brings are more important than the problems it causes).

Here’s my +1 to try this out.

Some links: * pitest: http://pitest.org/ * descartes: https://github.com/STAMP-project/pitest-descartes * http://massol.myxwiki.org/xwiki/bin/view/Blog/ControllingTestQuality * http://massol.myxwiki.org/xwiki/bin/view/Blog/MutationTestingDescartes

If you’re curious, you can see a screenshot of a mutation score report at http://massol.myxwiki.org/xwiki/bin/download/Blog/MutationTestingDescartes/r...

Please cast your votes.

Thanks -Vincent