ovedpo15 has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks!
I'm using Devel::Cover. I run my script on two different hosts (to test different envs). Let's call the first and the second one host X and host Y, respectively for convince.
The code that I test is the same on both sites (it's being copied first to those sites, before running the script).
I want to create one merged HTML report of those results (from both hosts). The way I run Devel::Cover: 
perl -MDevel::Cover=-silent,1,-db,${cover_db_path}" ${perl_script}

[download]
It creates the coverage db and then I can use the "cover" script to create the HTML report.

As I mentioned, I want to create one merged report of those dbs (from the two hosts). The problem is that the ${perl_script} is located in two different places. In host X I have /a/b/repo/run.py and in host Y I have /x/y/repo/run.py (please note that all of the perl scripts that I'm interested in are located under "repo" directory).
So I can sum up three problems that dependent on each other:
1. I can copy the cover_db from those sites but running the cover script will not work since it will not find those paths locally. It will create the report but it will have N/A for those paths, which of course makes sense, since it needs the source code.
2. I can run the cover script remotely on each site and create the reports but then how do I merge those HTML reports?
3. If it was possible to merge the HTML reports, how can I make them understand that /a/b/repo/* is the same as /x/y/repo/*?


I don't want it to become an X-Y problem so I would ask this - How would you merge two cover dbs that are located on two different hosts?

Replies are listed 'Best First'.
Re: How to merge two different coverage reports remotely
by choroba (Cardinal) on May 25, 2021 at 22:24 UTC
    Isn't it possible to create a directory /a/b with a symlink to /x/y/repo so that the paths are actually the same? Then, you should be able to merge the databases, too.

    I was able to make it work, but only for a very simple script. Make sure to backup or commit the coverage reports so you don't have to rerun the scripts every time you discover a problem.

    map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]
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[d/l]
      Then, you should be able to merge the databases, too. I was able to make it work, but only for a very simple script.

      From a high level, how did you go about doing it? Is it just concatenating some or all of the text files in the cover_db directory? Or do you have to do a manual interleave of data within each file? Or worse, a manual interleave-and-add for counts for certain lines of code? Is it just a subset of files that you have to merge?

      Sorry, since I've never looked into merging them before, or really even at the raw data -- I always just look at the HTML report at the end -- I wouldn't know where to start for the merge. Given the original question, it wouldn't surprise me if the OP was in the same boat as I am. So hints as to how to get started with the merge would be nice. (I am bookmarking this thread, since I think some of my repos might get better coverage numbers if I am able to eventually merge the linux and windows results; I'm reasonably confident that between the CI systems, I have full coverage, but being able to prove it would feel nice.)

[reply]
        No, I just copied the cover_db from one remote to a directory and ran 
        cover cover_db downloaded/cover_db

        [download]

        map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]
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Re: How to merge two different coverage reports remotely
by 1nickt (Canon) on May 25, 2021 at 20:57 UTC

    Hi,

    "The code that I test is the same on both sites"

    So why do you need to run the coverage report on both hosts?


    The way forward always starts with a minimal test.
[reply]
      Hi!
      Thank you for your comment. I test the code on different hosts, since it's depends on the environment. I copied the code to those hosts to be able to run it there and then get the results. It works but now I want to find the coverage. I want able to get the coverage for each one of them but I want to merge it into one report. The question is how?
[reply]

        Hi again,

        "I test the code on different hosts, since it's depends on the environment."

        That's one thing, and should be done for sure. But generating a test coverage report depends on the codebase, not the environment, unless you're using it in some way I've not encountered.


        The way forward always starts with a minimal test.
[reply]

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