Unit Tests does not run with latest Master

[avknaidu]

I'm submitting a...

Bug report (I searched for similar issues and did not find one)

Current behavior

None of the Unit Tests Except UnitTests.Notifications.NetCore runs with latest master.

Expected behavior

Unit Tests should run

Minimal reproduction of the problem with instructions

Pull or clone Latest Master and "Run All" unit Tests from "Test Explorer"

[22-May-18 2:37:12 AM Error] System.ArgumentException: The parameter is incorrect. (Exception from HRESULT: 0x80070057 (E_INVALIDARG))
   at EnvDTE.Properties.Item(Object index)
   at Microsoft.VisualStudio.TestWindow.VsAdapters.DeviceSelectionHelper.GetSelectedTargetDeviceType(IVsHierarchy vsHierarchy, Boolean isManagedProject)
   at Microsoft.VisualStudio.TestWindow.VsAdapters.VsTestContainer.InitializeTestContainer()
[22-May-18 2:37:12 AM Informational] ------ Run test started ------
[22-May-18 2:38:25 AM Error] Microsoft.VisualStudio.TestPlatform.ObjectModel.TestPlatformException: Failed to initialize client proxy: could not connect to test process.
   at Microsoft.VisualStudio.TestPlatform.CrossPlatEngine.Client.ProxyOperationManager.SetupChannel(IEnumerable`1 sources, CancellationToken cancellationToken)
   at Microsoft.VisualStudio.TestPlatform.CrossPlatEngine.Client.ProxyExecutionManager.StartTestRun(TestRunCriteria testRunCriteria, ITestRunEventsHandler eventHandler)
[22-May-18 2:38:25 AM Error] Microsoft.VisualStudio.TestPlatform.ObjectModel.TestPlatformException: Failed to initialize client proxy: could not connect to test process.
   at Microsoft.VisualStudio.TestPlatform.CrossPlatEngine.Client.ProxyOperationManager.SetupChannel(IEnumerable`1 sources, CancellationToken cancellationToken)
   at Microsoft.VisualStudio.TestPlatform.CrossPlatEngine.Client.ProxyExecutionManager.StartTestRun(TestRunCriteria testRunCriteria, ITestRunEventsHandler eventHandler)
[22-May-18 2:38:25 AM Informational] ========== Run test finished: 0 run (0:01:13.0770135) ==========

Environment

Nuget Package(s): 

Package Version(s): 

Windows 10 Build Number:
- [ ] Creators Update (15063)
- [ ] Fall Creators Update (16299)
- [x] April 2018 Update (17134)
- [ ] Insider Build (build number: )

App min and target version:
- [x] Creators Update (15063)
- [ ] Fall Creators Update (16299)
- [ ] April 2018 Update (17134)
- [ ] Insider Build (xxxxx)

Device form factor:
- [ ] Desktop
- [ ] Mobile
- [ ] Xbox
- [ ] Surface Hub
- [ ] IoT

Visual Studio 
- [X] 2017 (version: 15.7.1)
- [ ] 2017 Preview (version: )

[michael-hawker]

Started working on this on my dev stream, about 1/3ish the way through, but have at least already fixed a bug in the Markdown Parser, though thinking about #3200.

See branch progress here: https://github.com/windows-toolkit/WindowsCommunityToolkit/tree/testsCI%2BUnitTestFixes

[michael-hawker]

Note: We don't currently have any markdown tests for YAML.