Facing issue No source for code while combining multiple coverage files

[AGpta]

Describe the bug
A clear and concise description of the bug.
I have set up Azure CICD where i am running pytest-split to run unit test cases in parallel and every job generates .coverage.* file.
After completing all parallel jobs, i am downloading all coverage file in one place then running coverage combine and coverage xml command to get combined coverage report. In feb month it was running fine but in march, it stated giving bellow issue

To Reproduce
How can we reproduce the problem? Please be specific. Don't link to a failing CI job. Answer the questions below:

1. What version of Python are you using? 3.7
2. What version of coverage.py shows the problem? The output of coverage debug sys is helpful.

-- sys -------------------------------------------------------
               coverage_version: 7.4.3
                coverage_module: c:\hostedtoolcache\windows\python\3.8.10\x64\lib\site-packages\coverage\__init__.py
                           core: -none-
                        CTracer: available
           plugins.file_tracers: -none-
            plugins.configurers: -none-
      plugins.context_switchers: -none-
              configs_attempted: .coveragerc
                                 setup.cfg
                                 tox.ini
                                 pyproject.toml
                   configs_read: -none-
                    config_file: None
                config_contents: -none-
                      data_file: -none-

1. What versions of what packages do you have installed? The output of pip freeze is helpful.
2. What code shows the problem? Give us a specific commit of a specific repo that we can check out. If you've already worked around the problem, please provide a commit before that fix.
3. What commands should we run to reproduce the problem? Be specific. Include everything, even git clone, pip install, and so on. Explain like we're five!
   Below are task used in azure cicd. You can refer commands in below tasks.

      - task: CmdLine@2
        inputs:
          script: |
            pytest  --splits $(System.TotalJobsInPhase) --group $(System.JobPositionInPhase) --splitting-algorithm least_duration --store-durations --clean-durations -vv ./DataEngineering/Test/GTLS/ --cov=$(WORKING_DIR)/DataEngineering/GTLS/ --junitxml=test-unit.xml  --cov-report=xml --report-log=test-cases.$(System.JobPositionInPhase).json
          workingDirectory: '$(System.DefaultWorkingDirectory)'
        env:
          COVERAGE_FILE: .coverage.$(System.JobPositionInPhase)
        displayName: "Run Unit tests and generate coverage report"
      - script: | 
          pip install coverage
          coverage debug sys
          mv **/.coverage* .
          coverage combine --debug=pathmap
          coverage xml -o combined-coverage.xml
        workingDirectory: $(System.DefaultWorkingDirectory)
        displayName: Combining Coverage Reports

Expected behavior
A clear and concise description of what you expected to happen.
All coverage files should be combined into one which was previously happening but now it is giving error No source for code.
ss of previous Successful run:

Additional context
Add any other context about the problem here.

[nedbat]

It looks like you might be using different working directories for each split? Usually you need to re-map paths with the [paths] configuration: https://coverage.readthedocs.io/en/7.4.3/config.html#paths

Give that a try.

[AGpta]

hello Ned,

Issue is resolved.
Root cause: pytest command was running in ubuntu image and coverage combine command was running in windows image. This caused discrepancy in path.

I have one question: When coverage file is generated after combining all coverage files, what will happen to files with No coverage ? Will those files reduce code coverage?

[nedbat]

When coverage file is generated after combining all coverage files, what will happen to files with No coverage ? Will those files reduce code coverage?

To include completely unexecuted files in the measurement, use --source=. or something similar. Then coverage can find files that were never run.

[AGpta]

@nedbat i have to use --source=. in pytest command or coverage combine command??

[nedbat]

it's not an option on coverage combine, only coverage run. But you are already using the equivalent option for pytest-cov: --cov=....