Overwrite colorized lines instead of incremental updates

src/MSBuild.UnitTests/LiveLogger_Tests.cs

@@ -245,5 +245,45 @@ public Task PrintBuildSummary_FailedWithErrors()
         }
 
         #endregion
+
+        [Fact]
+        public void DisplayNodesShowsCurrent()
+        {
+            InvokeLoggerCallbacksForSimpleProject(succeeded: false, async () =>
+            {
+                _liveLogger.DisplayNodes();
+
+                await Verify(_outputWriter.ToString(), _settings);
+            });
+        }
+
+        [Fact]
+        public async Task DisplayNodesOverwritesWithNewTargetFramework()
+        {
+            BuildStarted?.Invoke(_eventSender, MakeBuildStartedEventArgs());
+
+            ProjectStartedEventArgs pse = MakeProjectStartedEventArgs(_projectFile, "Build");
+            pse.GlobalProperties = new Dictionary<string, string>() { ["TargetFramework"] = "tfName" };
+
+            ProjectStarted?.Invoke(_eventSender, pse);
+
+            TargetStarted?.Invoke(_eventSender, MakeTargetStartedEventArgs(_projectFile, "Build"));
+            TaskStarted?.Invoke(_eventSender, MakeTaskStartedEventArgs(_projectFile, "Task"));
+
+            _liveLogger.DisplayNodes();
+
+            // This is a bit fast and loose with the events that would be fired
+            // in a real "stop building that TF for the project and start building
+            // a new TF of the same project" situation, but it's enough now.
+            ProjectStartedEventArgs pse2 = MakeProjectStartedEventArgs(_projectFile, "Build");
+            pse2.GlobalProperties = new Dictionary<string, string>() { ["TargetFramework"] = "tf2" };
+
+            ProjectStarted?.Invoke(_eventSender, pse2);
+            TargetStarted?.Invoke(_eventSender, MakeTargetStartedEventArgs(_projectFile, "Build"));
+
+            _liveLogger.DisplayNodes();
+
+            await Verify(_outputWriter.ToString(), _settings);
+        }
     }
 }

src/MSBuild.UnitTests/Snapshots/LiveLogger_Tests.DisplayNodesOverwritesWithNewTargetFramework.verified.txt

@@ -0,0 +1,5 @@
+[?25l
+  project tfName Build (0.0s)
+[?25h[?25l
+  project tf2 Build (0.0s)
+[?25h

src/MSBuild.UnitTests/Snapshots/LiveLogger_Tests.DisplayNodesShowsCurrent.verified.txt

@@ -0,0 +1,3 @@
+[?25l
+  project Build (0.0s)
+[?25h

src/MSBuild/LiveLogger/LiveLogger.cs

@@ -611,7 +611,7 @@ private void ThreadProc()
     /// Render Nodes section.
     /// It shows what all build nodes do.
     /// </summary>
-    private void DisplayNodes()
+    internal void DisplayNodes()
     {
         NodesFrame newFrame = new NodesFrame(_nodes, width: Terminal.Width, height: Terminal.Height);
 
@@ -740,21 +740,22 @@ public string Render(NodesFrame previousFrame)
                     if (!previous.SequenceEqual(needed))
                     {
                         int commonPrefixLen = previous.CommonPrefixLength(needed);
-                        if (commonPrefixLen == 0)
+
+                        if (commonPrefixLen != 0 && needed.Slice(0, commonPrefixLen).IndexOf('\x1b') == -1)
                         {
-                            // whole string
-                            sb.Append(needed);
+                            // no escape codes, so can trivially skip substrings
+                            sb.Append($"{AnsiCodes.CSI}{commonPrefixLen}{AnsiCodes.MoveForward}");
+                            sb.Append(needed.Slice(commonPrefixLen));
                         }
                         else
                         {
-                            // set cursor to different char
-                            sb.Append($"{AnsiCodes.CSI}{commonPrefixLen}{AnsiCodes.MoveForward}");
-                            sb.Append(needed.Slice(commonPrefixLen));
-                            // Shall we clear rest of line
-                            if (needed.Length < previous.Length)
-                            {
-                                sb.Append($"{AnsiCodes.CSI}{AnsiCodes.EraseInLine}");
-                            }
+                            sb.Append(needed);
+                        }
+
+                        // Shall we clear rest of line
+                        if (needed.Length < previous.Length)
+                        {
+                            sb.Append($"{AnsiCodes.CSI}{AnsiCodes.EraseInLine}");
                         }
                     }
                 }

src/MSBuild/LiveLogger/Terminal.cs

@@ -107,7 +107,7 @@ public void Write(string text)
         }
         else
         {
-            Console.Write(text);
+            Output.Write(text);
         }
     }