Wait for design mode before closing a solution

src/VisualStudio/IntegrationTest/TestUtilities/InProcess/SolutionExplorer_InProc.cs

@@ -2,13 +2,15 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Runtime.InteropServices;
 using System.Threading;
 using System.Xml.Linq;
 using EnvDTE80;
 using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.EditAndContinue;
 using Microsoft.CodeAnalysis.Shared.TestHooks;
 using Microsoft.VisualStudio.ProjectSystem.Properties;
 using Microsoft.VisualStudio.Shell;
@@ -364,6 +366,12 @@ public void CleanUpOpenSolution()
                 }
             });
 
+            if (dte.Debugger.CurrentMode != EnvDTE.dbgDebugMode.dbgDesignMode)
+            {
+                dte.Debugger.TerminateAll();
+                WaitForDesignMode();
+            }
+
             CloseSolution();
             ErrorList_InProc.Create().WaitForNoErrorsInErrorList();
 
@@ -373,6 +381,35 @@ public void CleanUpOpenSolution()
             }
         }
 
+        private static void WaitForDesignMode()
+        {
+            var stopwatch = Stopwatch.StartNew();
+
+            // This delay was originally added to address test failures in BasicEditAndContinue. When running
+            // multiple tests in sequence, situations were observed where the Edit and Continue state was not reset:
+            //
+            // 1. Test A runs, starts debugging with Edit and Continue
+            // 2. Test A completes, and the debugger is terminated
+            // 3. A new project is created for test B
+            // 4. Test B attempts to set the text for the document created in step (3), but fails
+            //
+            // Step (4) was causing test failures because the project created for test B remained in a read-only
+            // state believing a debugger session was active.
+            //
+            // This delay should be replaced with a proper wait condition once the correct one is determined.
+            var editAndContinueService = GetComponentModelService<IEditAndContinueService>();
+            do
+            {
+                if (stopwatch.Elapsed >= Helper.HangMitigatingTimeout)
+                {
+                    throw new TimeoutException("Failed to enter design mode in a timely manner.");
+                }
+
+                Thread.Yield();
+            }
+            while (editAndContinueService?.DebuggingSession != null);
+        }
+
         private void CloseSolution()
         {
             var solution = GetGlobalService<SVsSolution, IVsSolution>();