CoverageDiff

A small utility to post-process an OpenCover XML file to only include sequence and branch points that are of interest. This filtered coverage file can still be used as an input of ReportGenerator to generate the coverage report just on the relevant code. The main motivation is to be able to quickly see the test coverage quality of a particular code patch or pull request by only showing the coverage details of the code specified by a Unified Diff file.

Usage

Options

>CoverageDiff.exe --help
CoverageDiff 1.0.0.0

  -c, --coverage    Required. OpenCover tool output as an XML file.
  -d, --diff        Required. Unified format patch file.
  -o, --output      Output file for mutated coverage xml file. If omitted then the coverage
                    file name with a '_diff' suffix added is used.
  --help            Display this help screen.
  --version         Display version information.
  
>

Example

git diff > sample.diff
CoverageDiff.exe -c OpenCover.xml -d sample.diff 
tools\ReportGenerator.exe -reports:OpenCover_diff.xml -targetdir:Html_Summary -reporttypes:Html;XmlSummary

Developer Notes

Assumptions

It appears that ReportGenerator performs its own coverage calculations based on the sequence and branch points in the open cover xml file. This meant I did not need to recalculate the Summary nodes inside the coverage file, and I use the XmlSummary output from the ReportGenerator tool.

Support for other formats

Currently only OpenOpen cover for coverage format and Unified Diff for source diff are supported. Other formats could easily be supported by implementing the appropriate interface.

Roadmap

1. Add a release build.
2. Add some tests.
3. Setup appveyor build and use this tool to provide coverage reports on pull requests. A live example.
4. Create a nuget package for easy script deployment.
5. Add a format selection algorithm to support other coverage formats, if somebody wants to add other format support.