fix

pester-extensions.psm1

@@ -12,7 +12,9 @@ function Get-CommandResult {
         [switch] $Multiline
     )
     # CMD trick to suppress and show error output because some commands write to stderr (for example, "python --version")
-    [string[]]$output = & $env:comspec /c "$Command 2>&1"
+    if ($IsWindows) {
+        [string[]]$output = & $env:comspec /c "$Command 2>&1"
+    }
     $exitCode = $LASTEXITCODE
 
     return @{