Improve code coverage for Microsoft.VisualBasic.dll (8.9%)

[danmoseley]

There are almost zero tests so there is essentially zero code coverage.

[stephentoub]

There are almost zero tests

The only reason there aren't exactly zero is because if there were zero, it wouldn't show up in the code coverage report at all, so I added one test to help highlight how bad we are here ;)

[ghost]

@stephentoub Well, that's pretty bad. ;) I could take this one. Is there an existing test codebase somewhere I could use as a starting point or do I have to start from scratch (I mean, from the one test you added :))?

[stephentoub]

Thanks, @dennisdietrich. That's a nice offer. @VSadov, do you know if there are existing tests for this internally somewhere?

[danmoseley]

Maybe from whatever repo @JeremyKuhne found the serial port tests recently.

[ghost]

Sure thing. I'll hold of with coding until we get a response regarding the (non)exists of test code for the assembly but please feel free to assign this issue to me.

[VSadov]

I will take a look if there is something salvageable.

[danmoseley]

@VSadov any luck?

[danmoseley]

Info on code coverage work:

1. Here's the all up report
   https://ci.dot.net/job/dotnet_corefx/job/master/job/code_coverage_windows/Code_Coverage_Report/
   Caveat - doesn't show coverage of any types whose implementation is in corelib (eg String, etc). If you want to look at that for now you must gather manually using instructions below.

2. Docs on code coverage work are here
   https://github.com/dotnet/corefx/blob/master/Documentation/building/code-coverage.md
   and some in
   https://github.com/dotnet/corefx/blob/master/Documentation/project-docs/developer-guide.md

3. There's innumerable places to add coverage -- we would love to focus on the most heavily used types and the least covered types to get the most benefit.

[ehasis]

I'm planing to contribute with this issue, but for some reason the there is no coverage (0 classes) for this assembly (actually Microsoft.VisualBasic.Core.dll). Any help in how to make code coverage show for this assembly?

[danmoseley]

@ehasis did you try https://github.com/dotnet/corefx/blob/master/Documentation/building/code-coverage.md#local-code-coverage-runs

[ehasis]

@danmosemsft yes, I tried that. I also tried test with coverage on the entire repository, the report showed for all the other assemblies, except the VisualBasic one.

[danmoseley]

@ViktorHofer is VB supposed to work? I would expect the tools to not be aware of the language used.

[ViktorHofer]

Seems to be a coverlet bug:

Unable to instrument module: C:\git\corefx2\artifacts\bin\testhost\netcoreapp-Windows_NT-Debug-x64\shared\Microsoft.NETCore.App\5.0.0\Microsoft.VisualBasic.Core.dll because : Object reference not set to an instance of an object.

cc @MarcoRossignoli

[MarcoRossignoli]

I'm OOF for a week I'll take a look asap @ViktorHofer please can you attach command line/project folder to speed up repro?

[ViktorHofer]

Submitted coverlet-coverage/coverlet#495 to fix the crash.

[ViktorHofer]

@ehasis that's the current code coverage status for Microsoft.VisualBasic.Core:

+----------------------------+--------+--------+--------+
| Module                     | Line   | Branch | Method |
+----------------------------+--------+--------+--------+
| Microsoft.VisualBasic.Core | 55.04% | 54.24% | 62.75% |
+----------------------------+--------+--------+--------+

+---------+--------+--------+--------+
|         | Line   | Branch | Method |
+---------+--------+--------+--------+
| Total   | 55.04% | 54.24% | 62.75% |
+---------+--------+--------+--------+
| Average | 55.04% | 54.24% | 62.75% |
+---------+--------+--------+--------+

HTML report:
report.zip

[ehasis]

Very nice, thanks @ViktorHofer !

[MarcoRossignoli]

Merged thanks Viktor

[ViktorHofer]

Submitted dotnet/corefx#39728 to consume the new version.

[cston]

Closing. If we identify specific types in Microsoft.VisualBasic.Core that require additional test coverage, we can address those cases with specific issues.