1 files changed, 88 insertions, 0 deletions

diff --git a/src/internal/WixBuildTools.TestSupport/ExternalExecutable.cs b/src/internal/WixBuildTools.TestSupport/ExternalExecutable.cs
new file mode 100644
index 00000000..eb07aa13
--- /dev/null
+++ b/src/internal/WixBuildTools.TestSupport/ExternalExecutable.cs
@@ -0,0 +1,88 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+namespace WixBuildTools.TestSupport
+{
+    using System.Collections.Concurrent;
+    using System.Collections.Generic;
+    using System.Diagnostics;
+    using System.IO;
+    using System.Text;
+
+    public abstract class ExternalExecutable
+    {
+        private readonly string exePath;
+
+        protected ExternalExecutable(string exePath)
+        {
+            this.exePath = exePath;
+        }
+
+        protected ExternalExecutableResult Run(string args, bool mergeErrorIntoOutput = false, string workingDirectory = null)
+        {
+            var startInfo = new ProcessStartInfo(this.exePath, args)
+            {
+                CreateNoWindow = true,
+                RedirectStandardError = true,
+                RedirectStandardOutput = true,
+                UseShellExecute = false,
+                WorkingDirectory = workingDirectory ?? Path.GetDirectoryName(this.exePath),
+            };
+
+            using (var process = Process.Start(startInfo))
+            {
+                // This implementation of merging the streams does not guarantee that lines are retrieved in the same order that they were written.
+                // If the process is simultaneously writing to both streams, this is impossible to do anyway.
+                var standardOutput = new ConcurrentQueue<string>();
+                var standardError = mergeErrorIntoOutput ? standardOutput : new ConcurrentQueue<string>();
+
+                process.ErrorDataReceived += (s, e) => { if (e.Data != null) { standardError.Enqueue(e.Data); } };
+                process.OutputDataReceived += (s, e) => { if (e.Data != null) { standardOutput.Enqueue(e.Data); } };
+
+                process.BeginErrorReadLine();
+                process.BeginOutputReadLine();
+
+                process.WaitForExit();
+
+                return new ExternalExecutableResult
+                {
+                    ExitCode = process.ExitCode,
+                    StandardError = mergeErrorIntoOutput ? null : standardError.ToArray(),
+                    StandardOutput = standardOutput.ToArray(),
+                    StartInfo = startInfo,
+                };
+            }
+        }
+
+        // This is internal because it assumes backslashes aren't used as escape characters and there aren't any double quotes.
+        internal static string CombineArguments(IEnumerable<string> arguments)
+        {
+            if (arguments == null)
+            {
+                return null;
+            }
+
+            var sb = new StringBuilder();
+
+            foreach (var arg in arguments)
+            {
+                if (sb.Length > 0)
+                {
+                    sb.Append(' ');
+                }
+
+                if (arg.IndexOf(' ') > -1)
+                {
+                    sb.Append("\"");
+                    sb.Append(arg);
+                    sb.Append("\"");
+                }
+                else
+                {
+                    sb.Append(arg);
+                }
+            }
+
+            return sb.ToString();
+        }
+    }
+}