[PT Run] [Folder Plugin] Environment Variables With Autocomplete (#13811)

* search environment variables folders with autocomplete

* refactoring and tests

* fix

src/modules/launcher/Plugins/Microsoft.Plugin.Folder.UnitTests/QueryEnvironmentVariableTests.cs

@@ -0,0 +1,67 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Generic;
+using System.IO.Abstractions.TestingHelpers;
+using System.Linq;
+using Microsoft.Plugin.Folder.Sources;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Moq;
+
+namespace Microsoft.Plugin.Folder.UnitTests
+{
+    [TestClass]
+    public class QueryEnvironmentVariableTests
+    {
+        private static IQueryEnvironmentVariable _queryEnvironmentVariable;
+        private static MockFileSystem _fileSystem;
+
+        [TestInitialize]
+        public void SetupMock()
+        {
+            var environmentHelperMock = new Mock<IEnvironmentHelper>();
+
+            environmentHelperMock
+                .Setup(h => h.GetEnvironmentVariables())
+                .Returns(() => new Dictionary<string, string>
+                {
+                    { "OS", "Windows_NT" },
+                    { "WINDIR", @"C:\Windows" },
+                    { "PROGRAMDATA", @"C:\ProgramData" },
+                    { "PROGRAMFILES", @"C:\Program Files" },
+                });
+
+            _fileSystem = new MockFileSystem(new Dictionary<string, MockFileData>()
+            {
+                { @"C:\Windows", new MockDirectoryData() },
+                { @"C:\ProgramData", new MockDirectoryData() },
+                { @"C:\Program Files", new MockDirectoryData() },
+            });
+
+            _queryEnvironmentVariable = new QueryEnvironmentVariable(_fileSystem.Directory, environmentHelperMock.Object);
+        }
+
+        [DataTestMethod]
+        [DataRow(@"%OS%")] // Not a directory
+        [DataRow(@"%CUSTOM%")] // Directory doesn't exist
+        [DataRow(@"WINDIR")] // Not an environment variable
+        public void QueryWithEmptyResults(string search)
+        {
+            var results = _queryEnvironmentVariable.Query(search);
+            Assert.AreEqual(results.Count(), 0);
+        }
+
+        [DataTestMethod]
+        [DataRow(@"", 3)]
+        [DataRow(@"%", 3)]
+        [DataRow(@"%WIN", 1)]
+        [DataRow(@"%WINDIR%", 1)]
+        [DataRow(@"%PROGRAM", 2)]
+        public void QueryWithResults(string search, int numberOfResults)
+        {
+            var results = _queryEnvironmentVariable.Query(search);
+            Assert.AreEqual(results.Count(), numberOfResults);
+        }
+    }
+}