9 Apr
2018
9 Apr
'18
3:40 p.m.
On 9 Apr 2018, at 15:34, Thomas Mortagne
<thomas.mortagne(a)xwiki.com> wrote:
On Mon, Apr 9, 2018 at 1:38 PM, Vincent Massol <vincent(a)massol.net> wrote:
As I said evocrash replicates exactly the same stack trace, including the message. If you
get something different it’s either because you’re executing on different code or whoever
generated the test made a mistake copying it.
Thanks
-Vincent
Hi Thomas,
If you execute the test indicated in
https://jira.xwiki.org/browse/XWIKI-13031?focusedCommentId=98082&page=c…
you will get the following exception:
java.lang.ClassCastException:
org.xwiki.model.internal.reference.ExplicitStringEntityReferenceResolver
cannot be cast to java.lang.String
Sure you get the same stack trace from Exception type and methods
calls point of view but what the message describe is a very different
use case. On 6 Apr 2018, at 11:57, Thomas Mortagne
<thomas.mortagne(a)xwiki.com> wrote:
Not sure what to think of those examples.
The theory sounds nice and it probably produce nice result when
talking about one method with a few inputs and an output but for
anything more complex (like anything involving components) I feel you
end up with a generated test which is a lot harder to read than simply
looking at the code.
As I said in my original mail, I think that really depends about who handles the issue (a
long time committer who’s being working for years on the code and knows it very well) or
someone new who doesn’t know the code well.
Also, it really depends on the context. Imagine the following example:you have a NPE
stack trace in production and the line where the NPE is has several variables that can be
null. Just looking at the code will not tell you what the problem is. But the test will
and you can even put a breakpoint to know which variable is actually null.
* https://jira.xwiki.org/browse/XWIKI-13031: does
not produce the same
error at all. Looks like evocash just try to produce any
ClassCastException but does not care about the actual types in it
which is quite useless (plus reading that test requires a lot of
effort just to conclude that the type of the field in the document is
not String…)
I’ve not tested them all but all the ones I’ve tested do reproduce correctly the stack
trace (that’s the point of evocrash so there’s no way it’ll generate a test that doesn’t
reproduce the stack trace! ;)).
To give you more info, you run evocrash by giving it a stacktrace and a frame number (the
number of stack trace lines you want it to reproduce).
For ex, on:
Caused by: java.lang.ClassCastException: org.apache.lucene.document.Field cannot be cast
to java.lang.String
at
org.xwiki.search.solr.internal.reference.SolrEntityReferenceResolver.getWikiReference(SolrEntityReferenceResolver.java:93)
~[xwiki-platform-search-solr-api-7.4.jar:na]
at
org.xwiki.search.solr.internal.reference.SolrEntityReferenceResolver.getEntityReference(SolrEntityReferenceResolver.java:70)
~[xwiki-platform-search-solr-api-7.4.jar:na]
at
org.xwiki.search.solr.internal.reference.SolrEntityReferenceResolver.resolve(SolrEntityReferenceResolver.java:63)
~[xwiki-platform-search-solr-api-7.4.jar:na]
at
org.xwiki.search.solr.internal.reference.SolrEntityReferenceResolver.resolve(SolrEntityReferenceResolver.java:46)
~[xwiki-platform-search-solr-api-7.4.jar:na]
at
org.xwiki.search.solr.internal.reference.SolrDocumentReferenceResolver.resolve(SolrDocumentReferenceResolver.java:48)
~[xwiki-platform-search-solr-api-7.4.jar:na]
at
org.xwiki.search.solr.internal.reference.SolrDocumentReferenceResolver.resolve(SolrDocumentReferenceResolver.java:38)
~[xwiki-platform-search-solr-api-7.4.jar:na]
[…]
If you run evocrash with frame = 5, it’ll generate a test that, when executed lead to:
Caused by: java.lang.ClassCastException: org.apache.lucene.document.Field cannot be cast
to java.lang.String
at
org.xwiki.search.solr.internal.reference.SolrEntityReferenceResolver.getWikiReference(SolrEntityReferenceResolver.java:93)
~[xwiki-platform-search-solr-api-7.4.jar:na]
at
org.xwiki.search.solr.internal.reference.SolrEntityReferenceResolver.getEntityReference(SolrEntityReferenceResolver.java:70)
~[xwiki-platform-search-solr-api-7.4.jar:na]
at
org.xwiki.search.solr.internal.reference.SolrEntityReferenceResolver.resolve(SolrEntityReferenceResolver.java:63)
~[xwiki-platform-search-solr-api-7.4.jar:na]
at
org.xwiki.search.solr.internal.reference.SolrEntityReferenceResolver.resolve(SolrEntityReferenceResolver.java:46)
~[xwiki-platform-search-solr-api-7.4.jar:na]
at
org.xwiki.search.solr.internal.reference.SolrDocumentReferenceResolver.resolve(SolrDocumentReferenceResolver.java:48)
~[xwiki-platform-search-solr-api-7.4.jar:na] * https://jira.xwiki.org/browse/XWIKI-14475:
totally unreadable
Actually this test was not that hard to read for me. It just sets up some mocks. Evocrash
can make it even simpler by presenting the mocks in a simpler way but that’s cosmetic and
not the focus of evocrash just right now (it’s not the hard part). I’ve also raised
something a bit related: https://github.com/STAMP-project/EvoCrash/issues/7
Feel free to raise new issues at https://github.com/STAMP-project/EvoCrash/issues/
* https://jira.xwiki.org/browse/XRENDERING-422:
not really useful but
I doubt evocrash can do much about this kind of issue
Yes I agree.
* https://jira.xwiki.org/browse/XWIKI-13196: this
one could help a bit
I guess but not sure it's really faster to execute evocash than
looking at the code :)
Sure but it also give you the test which is nice. And depending on the line generating
the NPE, it’s not always easy to know which variable is null by looking at the code.
* https://jira.xwiki.org/browse/XWIKI-13916:
that's a more complex way
than it should to express that we call addTextAreaField for an already
existing field yes it's useful
Thanks for the feedback.
There are plenty of limitations/issues with evocrash ATM. It’s good if we can identify
cases where it generates stuff that could be useful. One direction that the devs are
pursuing is looking at existing test classes to mimick how they’re written to produce the
new tests. I don’t know how they’d be able to pull this off (that seems really hard to me
;)) but I know they’re working in this direction.
Thanks
-Vincent
On Fri, Apr 6, 2018 at 10:44 AM, Vincent Massol <vincent(a)massol.net> wrote:
Hi devs,
Context
======
Evocrash is a tool developed as part of the STAMP research project
(https://www.stamp-project.eu/). Its goal is to take a stack trace (the use case is
production stack traces) and generate a test that, when executed, reproduces the stack
trace ;)
It’s using Guided Genetic Algorithm to simplify the search space (which is pretty cool,
isn’t it? ;)). More info at https://github.com/STAMP-project/EvoCrash and
http://www.evocrash.org/
Results
======
So far evocrash was able to generate tests for the following issues (I’ve pasted the
generated test code as comment):
* https://jira.xwiki.org/browse/XRENDERING-422
* https://jira.xwiki.org/browse/XWIKI-14475
* https://jira.xwiki.org/browse/XWIKI-13031
* https://jira.xwiki.org/browse/XWIKI-13196
* https://jira.xwiki.org/browse/XWIKI-13916
Using
=====
The use case I see is the following:
* A user reports a problem when using XWiki and create a jira issue with a stack trace
* An XWiki dev finds it and runs evocrash to generate a test reproducing the problem
* The XWiki dev uses the test to understand the reason (breakpoints can be put in the
IDE) of the problem and writes a better test (which can be inspired by the test generated
by evocrash or be completely different).
Questions
========
The question we need to answer is whether we think it coud be useful or not. Are there
cases where it can be useful?
For example if we imagine someone not knowing the xwiki code base well, maybe this can
help him/her understand the bug in a simpler way than just having to read/find where the
problem is in the code base?
I’ve started the work of trying to evaluate how useful it could be on the XWiki project
by analyzing the examples above. I've only analyzed 2 ATM (see the links in the jira
comments) and I’d be interested to have your analysis too.
WDYT?
Thanks
-Vincent
--
Thomas Mortagne