Adding RFC for MapNotRunnableToFailed (#71)

* Adding RFC for MapNotRunnableToFailed

* Adding change to the delta with v2 doc

RFCs/010-MapNotRunnableToFailed-Attribute.md

@@ -0,0 +1,20 @@
+# RFC 010 - Map not runnable tests to failed via runsettings
+
+## Motivation
+Some tests which have incompatible signature and cannot be executed are marked as skipped with warnings being thrown.
+User should be able to configure to fail a test if it is not runnable. 
+
+### Proposed solution
+Make this setting configurable via MapNotRunnableToFailed tag which is part of the adapter node in the runsettings.
+
+Here is a sample runsettings: 
+```xml
+<Runsettings> 
+  <MSTestV2> 
+    <MapNotRunnableToFailed>true</MapNotRunnableToFailed>   
+  </MSTestV2> 
+</Runsettings> 
+```
+
+### Honoring the settings 
+- If no settings are provided in runsettings, default MapNotRunnableToFailed is set to false. This has been kept in regard with backward compatibility.

docs/deltaWithMSTestV1.md

@@ -22,6 +22,14 @@ Listed are the difference in behaviour of MSTest V2 w.r.t MSTest V1 :
 ```
 11. The TestCleanup method on a TestClass is invoked even if its corresponding TestInitialize method fails. See [#250](https://github.com/Microsoft/testfx/issues/250) for details.
 12. The time taken by `AssemblyInitialize` and `ClassInitialize` are not considered as part of a tests duration thereby limiting their impact on a test timing out.
+13. Test which are not runnable can be configured to be marked as failed via MapNotRunnableToFailed tag which is part of the adapter node in the runsettings.
+ ```
+ <RunSettings>    
+  <MSTest> 
+    <MapNotRunnableToFailed>true</MapNotRunnableToFailed> 
+  </MSTest> 
+</RunSettings>
+```
 
 Here are the features that are not supported:
 1.	Tests cannot be included into an "Ordered Test".