Improve in-proc debugging (#731)

Improve in-proc debugging

Author: MarcoRossignoli

Documentation/Troubleshooting.md

@@ -239,8 +239,9 @@ Process Id: 29228 Name: dotnet
 
 ## Enable collector instrumentation debugging
 
-You can live attach and debug collectors with `COVERLET_DATACOLLECTOR_OUTOFPROC_DEBUG` env variable
+You can live attach and debug collectors with `COVERLET_DATACOLLECTOR_OUTOFPROC_DEBUG` and `COVERLET_DATACOLLECTOR_INPROC_DEBUG` env variable
 ```
  set COVERLET_DATACOLLECTOR_OUTOFPROC_DEBUG=1
+ set COVERLET_DATACOLLECTOR_INPROC_DEBUG=1
 ```
 You will be asket to attach a debugger through UI popup.

src/coverlet.collector/InProcDataCollection/CoverletInProcDataCollector.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics;
 using System.Reflection;
 
 using coverlet.collector.Resources;
@@ -14,8 +15,20 @@ public class CoverletInProcDataCollector : InProcDataCollection
     {
         private TestPlatformEqtTrace _eqtTrace;
 
+        private void AttachDebugger()
+        {
+            if (int.TryParse(Environment.GetEnvironmentVariable("COVERLET_DATACOLLECTOR_INPROC_DEBUG"), out int result) && result == 1)
+            {
+                Debugger.Launch();
+                Debugger.Break();
+            }
+        }
+
         public void Initialize(IDataCollectionSink dataCollectionSink)
         {
+
+            AttachDebugger();
+
             _eqtTrace = new TestPlatformEqtTrace();
             _eqtTrace.Verbose("Initialize CoverletInProcDataCollector");
         }