Added API to provide mutiple regex patterns for enumerating files.

src/Microsoft.TestPlatform.Client/TestPlatform.cs

@@ -175,15 +175,17 @@ private void AddExtensionAssemblies(string runSettings)
                     var adapterPath = Path.GetFullPath(Environment.ExpandEnvironmentVariables(customTestAdaptersPath));
                     if (!Directory.Exists(adapterPath))
                     {
-                        EqtTrace.Warning(string.Format("AdapterPath Not Found:", adapterPath));
+                        if (EqtTrace.IsWarningEnabled)
+                        {
+                            EqtTrace.Warning(string.Format("AdapterPath Not Found:", adapterPath));
+                        }
+
                         continue;
                     }
 
-                    var extensionAssemblies = new List<string>(this.fileHelper.EnumerateFiles(adapterPath, TestPlatformConstants.TestAdapterRegexPattern, SearchOption.AllDirectories));
-                    extensionAssemblies.AddRange(this.fileHelper.EnumerateFiles(adapterPath, TestPlatformConstants.TestLoggerRegexPattern, SearchOption.AllDirectories));
-                    extensionAssemblies.AddRange(this.fileHelper.EnumerateFiles(adapterPath, TestPlatformConstants.RunTimeRegexPattern, SearchOption.AllDirectories));
-                    extensionAssemblies.AddRange(this.fileHelper.EnumerateFiles(adapterPath, TestPlatformConstants.SettingsProviderRegexPattern, SearchOption.AllDirectories));
+                    var patterns = new string[] { TestPlatformConstants.TestAdapterRegexPattern, TestPlatformConstants.TestLoggerRegexPattern, TestPlatformConstants.RunTimeRegexPattern, TestPlatformConstants.SettingsProviderRegexPattern };
 
+                    var extensionAssemblies = new List<string>(this.fileHelper.EnumerateFiles(adapterPath, patterns, SearchOption.AllDirectories));
                     if (extensionAssemblies.Count > 0)
                     {
                         this.UpdateExtensions(extensionAssemblies, true);
@@ -215,7 +217,7 @@ private void AddExtensionAssembliesFromSource(TestRunCriteria testRunCriteria)
                 var sourceDirectory = Path.GetDirectoryName(source);
                 if (!string.IsNullOrEmpty(sourceDirectory) && this.fileHelper.DirectoryExists(sourceDirectory))
                 {
-                    loggersToUpdate.AddRange(this.fileHelper.EnumerateFiles(sourceDirectory, TestPlatformConstants.TestLoggerRegexPattern, SearchOption.TopDirectoryOnly).ToList());
+                    loggersToUpdate.AddRange(this.fileHelper.EnumerateFiles(sourceDirectory, TestPlatformConstants.TestLoggerRegexPattern, SearchOption.TopDirectoryOnly));
                 }
             }
 
@@ -233,13 +235,9 @@ private static void AddExtensionAssembliesFromExtensionDirectory()
         {
             var fileHelper = new FileHelper();
             var extensionsFolder = Path.Combine(Path.GetDirectoryName(typeof(TestPlatform).GetTypeInfo().Assembly.Location), "Extensions");
-            var defaultExtensionPaths = new List<string>();
             if (fileHelper.DirectoryExists(extensionsFolder))
             {
-                var dlls = fileHelper.EnumerateFiles(extensionsFolder, ".*.dll", SearchOption.TopDirectoryOnly);
-                defaultExtensionPaths.AddRange(dlls);
-                var exes = fileHelper.EnumerateFiles(extensionsFolder, ".*.exe", SearchOption.TopDirectoryOnly);
-                defaultExtensionPaths.AddRange(exes);
+                var defaultExtensionPaths = fileHelper.EnumerateFiles(extensionsFolder, new string[] { ".*.dll", ".*.exe" }, SearchOption.TopDirectoryOnly);
                 TestPluginCache.Instance.DefaultExtensionPaths = defaultExtensionPaths;
             }
         }

src/Microsoft.TestPlatform.CoreUtilities/Helpers/FileHelper.cs

@@ -53,6 +53,12 @@ public IEnumerable<string> EnumerateFiles(string directory, string pattern, Sear
             return Directory.EnumerateFiles(directory, "*", searchOption).Where(f => regex.IsMatch(f));
         }
 
+        /// <inheritdoc/>
+        public IEnumerable<string> EnumerateFiles(string directory, string[] patterns, SearchOption searchOption)
+        {
+            return this.EnumerateFiles(directory, string.Join("|", patterns), searchOption);
+        }
+
         /// <inheritdoc/>
         public FileAttributes GetFileAttributes(string path)
         {

src/Microsoft.TestPlatform.CoreUtilities/Helpers/Interfaces/IFileHelper.cs

@@ -56,6 +56,15 @@ public interface IFileHelper
         /// <returns>List of files matching the pattern.</returns>
         IEnumerable<string> EnumerateFiles(string directory, string pattern, SearchOption searchOption);
 
+        /// <summary>
+        /// Enumerates files which match multiple patterns (case insensitive) in a directory.
+        /// </summary>
+        /// <param name="directory">Parent directory to search.</param>
+        /// <param name="patterns">Search patterns.</param>
+        /// <param name="searchOption"><see cref="SearchOption"/> for directory.</param>
+        /// <returns>List of files matching the pattern.</returns>
+        IEnumerable<string> EnumerateFiles(string directory, string[] patterns, SearchOption searchOption);
+
         /// <summary>
         /// Gets attributes of a file.
         /// </summary>

test/Microsoft.TestPlatform.PerformanceTests/FileHelperTests.cs

@@ -0,0 +1,67 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+namespace Microsoft.TestPlatform.PerformanceTests
+{
+    using System.Collections.Generic;
+    using System.Diagnostics;
+    using System.IO;
+
+    using Microsoft.TestPlatform.TestUtilities.PerfInstrumentation;
+    using Microsoft.VisualStudio.TestPlatform.Utilities.Helpers;
+    using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+    [TestClass]
+    public class FileHelperTests : PerformanceTestBase
+    {
+        [TestMethod]
+        public void EnumerateFilesPerfTests()
+        {
+            var fileHelper = new FileHelper();
+            var stopwatch = new Stopwatch();
+            var adapterPath = Directory.GetCurrentDirectory();
+            var patterns = new string[]
+                              {
+                                   ".*CoreUtilities.dll",
+                                   ".*CommunicationUtilities.dll",
+                                   ".*CrossPlatEngine.dll",
+                                   ".*TestUtilities.dll"
+                              };
+
+            stopwatch.Start();
+            var extensionAssemblies =
+                new List<string>(
+                    fileHelper.EnumerateFiles(
+                        adapterPath,
+                       patterns[0],
+                        SearchOption.AllDirectories));
+            extensionAssemblies.AddRange(
+                fileHelper.EnumerateFiles(
+                    adapterPath,
+                    patterns[1],
+                    SearchOption.AllDirectories));
+            extensionAssemblies.AddRange(
+                fileHelper.EnumerateFiles(
+                    adapterPath,
+                    patterns[2],
+                    SearchOption.AllDirectories));
+            extensionAssemblies.AddRange(
+                fileHelper.EnumerateFiles(
+                    adapterPath,
+                    patterns[3],
+                    SearchOption.AllDirectories));
+
+            stopwatch.Stop();
+            var timeForOldApi = stopwatch.ElapsedMilliseconds;
+
+            stopwatch.Restart();
+            var extensionAssembliesNew =
+                new List<string>(fileHelper.EnumerateFiles(adapterPath, patterns, SearchOption.AllDirectories));
+            stopwatch.Stop();
+            var timeForNewApi = stopwatch.ElapsedMilliseconds;
+
+            Assert.AreEqual(extensionAssemblies.Count, extensionAssembliesNew.Count);
+            Assert.IsTrue(timeForNewApi < timeForOldApi);
+        }
+    }
+}