Daniel Palme

Daniel Palme

.NET consultant from Germany.

Blog > PartCover - Coverage of unexecuted methods - Part 2

PartCover - Coverage of unexecuted methods - Part 2

A few weeks ago I blogged about a problem concerning coverage of unexecuted code in PartCover. The problem was that the report generated by PartCover does not contain any coverage information about uncovered methods. That implicated, that my tool ReportGenerator calculated a wrong coverage quota, since the lines of unexecuted method were considered to be 'not visitable'.
I claimed that it would not be easy to create a workaround for the problem, but actually it isn't that difficult, if you use the right tools.

The problem

The report generated by PartCover contains only one utilizable piece of information: The signature of the method (e.g. 'void (int, long)'). Based on the signature we have to search the method within the source files and determine its start and end line number. As explained in my previous post this can not be accomplished on a source code level.

The solution

One of my readers pointed me to the NRefactory library, which is part of SharpDevelop.
With the following snippet you can get an AST of a code file:

INode ast;

using (var parser = ICSharpCode.NRefactory.ParserFactory.CreateParser(filename))
{
  parser.Parse();
  ast = parser.CompilationUnit.CurrentBock;
}

Now you can recursively search the syntax tree for a method matching the signature extracted from the PartCover report. You have to perform some mappings between type names, since the type names used in the signature are not named consistently (e.g. string for System.String).
Once you found the correct element within the AST, you obtain the line numbers very easily:

MethodDeclaration methodDeclaration = node as MethodDeclaration;
if (methodDeclaration != null)
{
  int startLine = methodDeclaration.Body.StartLocation.Line;
  int endLine = methodDeclaration.Body.EndLocation.Line;
}

Conclusion

The latest version of ReportGenerator already uses the NRefactory library to get coverage information for unexecuted methods and constructors.


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Comments

#1
Shaun Wilde

Shaun Wilde

07/21/2010

Glad you resolved the issue.

Just to let you know that partcover now supports .NET 4.0
 
#2
Markus Ewald

Markus Ewald

08/18/2010 | http://www.nuclex.org

Thanks for this tool! The reports generated by the XSLTs shipped with PartCover look really dull.

It does take a bit long on my project, though. For an 1.5 MiB coverage.xml file, it crunched away for 21 minutes (on a 3 GHz CPU). This is the only reason I haven't added it to my automated TeamCity builds.

Would it be possible to add the option to just generate a summary report similar to NCoverExplorer? Only if the bottleneck really is parsing the individual source files, of course :)
 
#3
Daniel

Daniel

08/18/2010

@Markus:
Thanks for your feedback. That's definitifly too long for a 1.5 MB report. I have sent you an email, please provide me your report file (not your source code). I will take a look at the problem.