Create code coverage reports

[angularsen]

Testing out codecov.io for test coverage reports on pull requests, with diffs against master.

• Use OpenCoverage dotCover to produce statistics
• Use ReportGenerator to merge reports and produce an HTML report (not dependent on CodeCov.io)
• Upload coverage reports to https://codecov.io/gh/angularsen/UnitsNet for online reports

I tried OpenCoverage first, but I ran into heaps of trouble and it seems the project is not very actively maintained. dotCover CLI tools does not require a license as far as I can tell and is much faster to run.

[angularsen]

Currently getting error messages about not finding .pdb files on AppVeyor, but the same commands work locally when building with build.bat. Not sure why exactly.

https://ci.appveyor.com/project/angularsen/unitsnet/builds/24002213

OpenCover.Console.exe -target:"dotnet.exe" -targetargs:"test UnitsNet.Tests" -output:"Artifacts/UnitsNet.Tests.coverage.xml" -filter:"+[UnitsNet*]* -[UnitsNet.Tests*]*" -oldstyle -register:user
Executing: C:\Program Files\dotnet\dotnet.exe
Test run for C:\projects\unitsnet\Artifacts\UnitsNet.Tests\netcoreapp2.0\UnitsNet.Tests.dll(.NETCoreApp,Version=v2.0)
Microsoft (R) Test Execution Command Line Tool Version 16.0.1
Copyright (c) Microsoft Corporation.  All rights reserved.
Starting test execution, please wait...
Total tests: 2736. Passed: 2736. Failed: 0. Skipped: 0.
Test Run Successful.
Test execution time: 11.3785 Seconds
Committing...
[NOTE] Post processing coverage data...
No results, this could be for a number of reasons. The most common reasons are:
    1) missing PDBs for the assemblies that match the filter please review the
    output file and refer to the Usage guide (Usage.rtf) about filters.
    2) the profiler may not be registered correctly, please refer to the Usage
    guide and the -register switch.

Links:
https://automationrhapsody.com/code-coverage-net-core-unit-tests-opencover/
https://www.appveyor.com/blog/2017/03/17/codecov/

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@1c6c629). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #657   +/-   ##
=========================================
  Coverage          ?   55.56%           
=========================================
  Files             ?      164           
  Lines             ?    37408           
  Branches          ?        0           
=========================================
  Hits              ?    20786           
  Misses            ?    16622           
  Partials          ?        0

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 1c6c629...808808f. Read the comment docs.

[angularsen]

Well whoop, it finally works. The numbers are horrible of course, but we'll improve that by either filtering out stuff or converting tests to test for N units.

[tmilnthorp]

Looks good - but yikes. Do you mean that coverage isn't calculated properly until we switch to NUnit from XUnit?

[angularsen]

I didn't mean NUnit :-D

I meant going from "hey here is a test case that tests Length, Mass and some other widely used quantities all in one go" to maybe generating unique test cases for every quantity and unit - in order to get better test coverage.

But yeah, I'll have to look closer at the numbers. I was mostly happy that I got it working at all as a start :-P

[angularsen]

I'll take a second look at why the numbers are so bad before merging this.

[angularsen]

@tmilnthorp Wohoo! After switching from OpenCover to dotCover I got more sane results and way better performance. 56% coverage now, which sounds reasonable given that many tests only target specific quantities.

I believe the licensing for the CLI tooling is OK, but I have also applied for an open source license just to be sure. Merging this now so we can get a baseline going for future PRs.

[tmilnthorp]

Sweet. Still surprised though given all the As/To methods

[angularsen]

Added issue to follow up improving the coverage numbers:
#682