From 2f3f39906f6f58e1028672ae3aeffb83934c5153 Mon Sep 17 00:00:00 2001
From: Steve Lee <slee@microsoft.com>
Date: Mon, 12 Apr 2021 20:11:50 -0700
Subject: [PATCH] resolve merge conflict (#14969)

---
 .../host/msh/ConsoleHostUserInterface.cs      | 32 +++++++++++++++-
 test/powershell/Host/ConsoleHost.Tests.ps1    | 37 +++++++++++++++++++
 2 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/src/Microsoft.PowerShell.ConsoleHost/host/msh/ConsoleHostUserInterface.cs b/src/Microsoft.PowerShell.ConsoleHost/host/msh/ConsoleHostUserInterface.cs
index 14425da82c..6d0c0ff250 100644
--- a/src/Microsoft.PowerShell.ConsoleHost/host/msh/ConsoleHostUserInterface.cs
+++ b/src/Microsoft.PowerShell.ConsoleHost/host/msh/ConsoleHostUserInterface.cs
@@ -60,8 +60,38 @@ namespace Microsoft.PowerShell
 
             _parent = parent;
             _rawui = new ConsoleHostRawUserInterface(this);
-            SupportsVirtualTerminal = TryTurnOnVtMode();
+            SupportsVirtualTerminal = true;
             _isInteractiveTestToolListening = false;
+
+            if (ExperimentalFeature.IsEnabled("PSAnsiRendering"))
+            {
+                // check if TERM env var is set
+                // `dumb` means explicitly don't use VT
+                // `xterm-mono` and `xtermm` means support VT, but emit plaintext
+                switch (Environment.GetEnvironmentVariable("TERM"))
+                {
+                    case "dumb":
+                        SupportsVirtualTerminal = false;
+                        break;
+                    case "xterm-mono":
+                    case "xtermm":
+                        PSStyle.Instance.OutputRendering = OutputRendering.PlainText;
+                        break;
+                    default:
+                        break;
+                }
+
+                // widely supported by CLI tools via https://no-color.org/
+                if (Environment.GetEnvironmentVariable("NO_COLOR") != null)
+                {
+                    PSStyle.Instance.OutputRendering = OutputRendering.PlainText;
+                }   
+            }
+
+            if (SupportsVirtualTerminal)
+            {
+                SupportsVirtualTerminal = TryTurnOnVtMode();
+            }
         }
 
         internal bool TryTurnOnVtMode()
diff --git a/test/powershell/Host/ConsoleHost.Tests.ps1 b/test/powershell/Host/ConsoleHost.Tests.ps1
index e57b6357c7..667ef77824 100644
--- a/test/powershell/Host/ConsoleHost.Tests.ps1
+++ b/test/powershell/Host/ConsoleHost.Tests.ps1
@@ -1008,3 +1008,40 @@ Describe 'Console host name' -Tag CI {
         (Get-Process -Id $PID).Name | Should -BeExactly 'pwsh'
     }
 }
+
+Describe 'TERM env var' -Tag CI {
+    BeforeAll {
+        $oldTERM = $env:TERM
+        $PSDefaultParameterValues.Add('It:Skip', (-not $EnabledExperimentalFeatures.Contains('PSAnsiRendering')))
+    }
+
+    AfterAll {
+        $env:TERM = $oldTERM
+        $PSDefaultParameterValues.Remove('It:Skip')
+    }
+
+    It 'TERM = "dumb"' {
+        $env:TERM = 'dumb'
+        pwsh -noprofile -command '$Host.UI.SupportsVirtualTerminal' | Should -BeExactly 'False'
+    }
+
+    It 'TERM = "<term>"' -TestCases @(
+        @{ term = "xterm-mono" }
+        @{ term = "xtermm" }
+    ) {
+        param ($term)
+
+        $env:TERM = $term
+        pwsh -noprofile -command '$PSStyle.OutputRendering' | Should -BeExactly 'PlainText'
+    }
+
+    It 'NO_COLOR' {
+        try {
+            $env:NO_COLOR = 1
+            pwsh -noprofile -command '$PSStyle.OutputRendering' | Should -BeExactly 'PlainText'
+        }
+        finally {
+            $env:NO_COLOR = $null
+        }
+    }
+}