Support for Deterministic Source Paths

[clairernovotny]

Today, it appears that ReportGenerator requires the "real" path to a file to work. If ContinousIntegrationBuild is set to true though, the paths in the report files should generate file paths of the like

/_/some/directory/file.cs
/_/some/directory/file2.cs
/_1/anotherRoot/frob/bar.cs

etc.

They'll always be normalized across OS versions.

What we'd need is for the sources parameter to search against all roots (ignore the /_{n}/) and try to find it against something like

C:\agent\1\work\s\some\directory\file.cs
C:\agent\1\work\s\some\directory\file2.cs

and match the files.

What can we do here?

Thanks!

[danielpalme]

I'm not sure I understand your problem correctly.

If you use the -sourcedirs command line parameter, ReportGenerator tries to locate the file by combining all the sourcedirectories, with all possible sub directories/files.

See:
https://github.com/danielpalme/ReportGenerator/blob/master/src/ReportGenerator.Core/Parser/FileReading/LocalFileReader.cs#L74

If you use -sourcedirs:C:\agent\1\work\s it will try to locate the file '/_/some/directory/file.cs` at these locations:

C:\agent\1\work\s\_\some\directory\file.cs
C:\agent\1\work\s\some\directory\file.cs
C:\agent\1\work\s\directory\file.cs
C:\agent\1\work\s\file.cs

The file C:\agent\1\work\s\some\directory\file.cs should be a match in your case.

Does this help?
If not, a concrete sample would help:

• Coverage file
• directory/file structure in your working directory
• parameters passed to ReportGenerator

[clairernovotny]

Providing the source directory did solve the warnings, but in each of the type files, it seems to be duplicating the overlay (and possibly not fully merging the line hit counts)?

Concretely, I have a result that looks like this with these two file names (same type, ByteArray):

/home/vsts/work/1/s/Collections/Specialized/ByteArray.cs
C:\a\1\s\Collections\Specialized\ByteArray.cs

The section of the report that shows the overlay is repeated twice, one for each file, so it's not clear that the line hit-counts are merged--what I want is to have those normalized and merged (they're the same file) to a single overlay.

[clairernovotny]

@MarcoRossignoli seems like you can write out the deterministic path in the cobertura file instead of the local file path. That'll fix the merging issues. The only requirement then will be that -sourcedirs is always passed in to report generator since all paths will start with /_.../

@danielpalme it may be worth an either a specific error or some reasonable default if ReportGenerator detects that the path starts with /_ so things "just work" for users who fully enable deterministic builds.

[MarcoRossignoli]

Maybe on coverlet side we should add a flag like --deterministic-report to avoid to break other report generators.

[danielpalme]

@clairernovotny
Can you please share the coverage files containing the coverage information regarding ByteArray.cs?
I would like to debug this, to understand why merging does not work for you.
You can also send the files by email (reportgenerator@palmmedia.de) if you don't want to share them publicly.

[danielpalme]

@clairernovotny
Thanks for your email. I will have a look within the next days.

[danielpalme]

I took a look at @clairernovotny files.

In your coverage files all paths start with:

• C:\a\1\s\ (Windows)
• /home/vsts/work/1/s/ (Linux)

I understand that the following paths actually mean the same file:

• /home/vsts/work/1/s/Collections/Specialized/ByteArray.cs
• C:\a\1\s\Collections\Specialized\ByteArray.cs

In the class coverage report generated by ReportGenerator, you would expect that e.g. for class ByteArray1, only one code file is listed.
That means, that ReportGenerator needs to treat both paths as the same file and only read one of the files from disk (the actual path depends on the operating system on which ReportGenerator is executed).

For me that means, we need a way to tell ReportGenerator that certain paths are mapped to other paths.
This could be done "manually" by specifying directory mappings (e.g. C:\a\1\s\ -> /home/vsts/work/1/s/) or by defining the most common path mappings (e.g. for Azure DevOps and GitHub Actions) and map them automatically (or maybe with a command line switch).

What I don't understand yet:

• You mentioned paths starting with /_. Your coverage files don't contain any paths starting with /_
• How does this relate to deterministic build? The paths should stay the same in a deterministic build? Or am I wrong here?

[clairernovotny]

The files don't contain anything that starts with /_ today because Coverlet outputs the real path information into the coverage file instead of the deterministic path. Without any special parameters to ReportGenerator (passing in -sourcedirs:), that turns into a not-so-great user experience.

Coverlet could add an option as @MarcoRossignoli suggests in #405 (comment) where it'd write the deterministic file paths instead.

If they do that, on both Windows and Linux, the path would look something like

/_/Collections/Specialized/ByteArray.cs
/_/Collections/Specialized/CharArray.cs
or
/_1/OtherThingSourceRoot/SomeOtherThing/Foo.cs
/_2/YetAnotherSourceRoot/AnotherOtherThing/Bar.cs

In that case, ReportGenerator wouldn't need to do any special mapping of paths when matching types/files, but a user would have to pass in -sourcedirs: (I believe) so the search will work.

[danielpalme]

Thanks. Now I got it.

Adding support for this format should be easy in ReportGenerator.
The -sourcedirs parameter could also be optional. If no -sourcedirs are supplied, ReportGenerator can also check if the files exist at the default location for the most common CI/CD tools.

[MarcoRossignoli]

@danielpalme @clairernovotny you can try preview package of coverlet with deterministic report support https://f.feedz.io/marcorossignoli/coverletunofficial/nuget/index.json version 3.0.3-preview.6.ge4534aed18

-- deterministic build
dotnet build /p:Deterministic=true /p:ContinuousIntegrationBuild=true 

-- Collectors integration
dotnet test --no-build --collect:"XPlat Code Coverage" -- DataCollectionRunSettings.DataCollectors.DataCollector.Configuration.Format=cobertura DataCollectionRunSettings.DataCollectors.DataCollector.Configuration.DeterministicReport=true
-- Msbuild
dotnet test --no-build /p:DeterministicReport=true /p:CollectCoverage=true /p:CoverletOutputFormat=cobertura
-- Report generator
reportgenerator -reports:C:\git\coverletissue\DeterministicBuilds\MyTests\TestResults\438b7150-5a9a-4208-8d37-3f694ae90f75\coverage.cobertura.xml -targetdir:C:\git\coverletissue\DeterministicBuilds\MyTests\TestResults\438b7150-5a9a-4208-8d37-3f694ae90f75\ --sourcedirs:C:\git\coverletissue\DeterministicBuilds

<?xml version="1.0" encoding="utf-8"?>
<coverage line-rate="0.8571" branch-rate="0.5" version="1.9" timestamp="1612702997" lines-covered="6" lines-valid="7" branches-covered="1" branches-valid="2">
  <sources />
  <packages>
    <package name="MyLibrary" line-rate="0.8571" branch-rate="0.5" complexity="3">
      <classes>
        <class name="MyLibrary.Hello" filename="/_/MyLibrary/Hello.cs" line-rate="0.8571" branch-rate="0.5" complexity="3">
          <methods>
            <method name="get_Who" signature="()" line-rate="1" branch-rate="1" complexity="1">
              <lines>
                <line number="15" hits="1" branch="False" />
              </lines>
            </method>
            <method name=".ctor" signature="(System.String)" line-rate="0.8332999999999999" branch-rate="0.5" complexity="2">
              <lines>
                <line number="7" hits="1" branch="False" />
                <line number="8" hits="1" branch="False" />
                <line number="9" hits="1" branch="True" condition-coverage="50% (1/2)">
                  <conditions>
                    <condition number="16" type="jump" coverage="50%" />
                  </conditions>
                </line>
                <line number="10" hits="0" branch="False" />
                <line number="12" hits="1" branch="False" />
                <line number="13" hits="1" branch="False" />
              </lines>
            </method>
...

Expected result with current version of reportgenerator

[danielpalme]

@MarcoRossignoli
Thanks for the preview version of coverlt.
I will add the necessary code changes as soon as possible.
It may take some time, since I'm pretty busy.

[clairernovotny]

@MarcoRossignoli I tried out that version and it seems to have worked!

[danielpalme]

@MarcoRossignoli
I just tried your previews:

• coverlet.msbuild 3.0.3-preview.6.ge4534aed18
• coverlet.collector 3.0.3-preview.6.ge4534aed18

With both packages, I get the full path path instead of the determistic path in coverage.cobertura.xml

Any idea what's wrong? Here is my test project:
coveragesample_msbuild.zip