diff --git a/src/modules/launcher/Plugins/Wox.Plugin.Indexer/SearchHelper/WindowsSearchAPI.cs b/src/modules/launcher/Plugins/Wox.Plugin.Indexer/SearchHelper/WindowsSearchAPI.cs
index b51bf1e4c7..64875595a1 100644
--- a/src/modules/launcher/Plugins/Wox.Plugin.Indexer/SearchHelper/WindowsSearchAPI.cs
+++ b/src/modules/launcher/Plugins/Wox.Plugin.Indexer/SearchHelper/WindowsSearchAPI.cs
@@ -7,9 +7,9 @@ namespace Wox.Plugin.Indexer.SearchHelper
 {
     public class WindowsSearchAPI
     {
-        private OleDbConnection conn;
-        private OleDbCommand command;
-        private OleDbDataReader WDSResults;
+        public OleDbConnection conn;
+        public OleDbCommand command;
+        public OleDbDataReader WDSResults;
 
         public IEnumerable<SearchResult> ExecuteQuery(ISearchQueryHelper queryHelper, string keyword)
         {
@@ -43,7 +43,8 @@ namespace Wox.Plugin.Indexer.SearchHelper
             }
         }
 
-        public void setQueryHelper(ref ISearchQueryHelper queryHelper, string pattern)
+
+        public void ModifyQueryHelper(ref ISearchQueryHelper queryHelper, string pattern)
         {
             // convert file pattern if it is not '*'. Don't create restriction for '*' as it includes all files.
             if (pattern != "*")
@@ -63,7 +64,7 @@ namespace Wox.Plugin.Indexer.SearchHelper
             }
         }
 
-        public IEnumerable<SearchResult> Search(string keyword, string pattern = "*", int maxCount = 100)
+        public void InitQueryHelper(out ISearchQueryHelper queryHelper, int maxCount)
         {
             // This uses the Microsoft.Search.Interop assembly
             CSearchManager manager = new CSearchManager();
@@ -72,7 +73,7 @@ namespace Wox.Plugin.Indexer.SearchHelper
             ISearchCatalogManager catalogManager = manager.GetCatalog("SystemIndex");
 
             // Get the ISearchQueryHelper which will help us to translate AQS --> SQL necessary to query the indexer
-            ISearchQueryHelper queryHelper = catalogManager.GetQueryHelper();
+            queryHelper = catalogManager.GetQueryHelper();
 
             // Set the number of results we want. Don't set this property if all results are needed.
             queryHelper.QueryMaxResults = maxCount;
@@ -85,9 +86,13 @@ namespace Wox.Plugin.Indexer.SearchHelper
 
             // Set sorting order 
             queryHelper.QuerySorting = "System.DateModified DESC";
+        }
 
-            setQueryHelper(ref queryHelper, pattern);
-
+        public IEnumerable<SearchResult> Search(string keyword, string pattern = "*", int maxCount = 100)
+        {
+            ISearchQueryHelper queryHelper;
+            InitQueryHelper(out queryHelper, maxCount);
+            ModifyQueryHelper(ref queryHelper, pattern);
             return ExecuteQuery(queryHelper, keyword);
         }
     }
diff --git a/src/modules/launcher/Plugins/Wox.Plugin.Indexer/Wox.Plugin.Indexer.csproj b/src/modules/launcher/Plugins/Wox.Plugin.Indexer/Wox.Plugin.Indexer.csproj
index c4c78bf4d4..1a7bdbe8c7 100644
--- a/src/modules/launcher/Plugins/Wox.Plugin.Indexer/Wox.Plugin.Indexer.csproj
+++ b/src/modules/launcher/Plugins/Wox.Plugin.Indexer/Wox.Plugin.Indexer.csproj
@@ -9,9 +9,10 @@
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <RootNamespace>Wox.Plugin.Indexer</RootNamespace>
     <AssemblyName>Wox.Plugin.Indexer</AssemblyName>
-    <TargetFrameworkVersion>v4.7.2</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v4.5.2</TargetFrameworkVersion>
     <FileAlignment>512</FileAlignment>
     <Deterministic>true</Deterministic>
+    <TargetFrameworkProfile />
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <DebugSymbols>true</DebugSymbols>
diff --git a/src/modules/launcher/Wox.Test/Plugins/WindowsIndexerTest.cs b/src/modules/launcher/Wox.Test/Plugins/WindowsIndexerTest.cs
new file mode 100644
index 0000000000..9df2aa5892
--- /dev/null
+++ b/src/modules/launcher/Wox.Test/Plugins/WindowsIndexerTest.cs
@@ -0,0 +1,145 @@
+using NUnit.Framework;
+using System;
+using System.Collections.Generic;
+using System.Data.OleDb;
+using Microsoft.Search.Interop;
+using Wox.Plugin.Indexer.SearchHelper;
+
+namespace Wox.Test.Plugins
+{
+
+    [TestFixture]
+    public class WindowsIndexerTest
+    {
+        private WindowsSearchAPI _api = new WindowsSearchAPI();
+
+        [Test]
+        public void InitQueryHelper_ShouldInitialize_WhenFunctionIsCalled()
+        {
+            // Arrange
+            int maxCount = 10;
+            ISearchQueryHelper queryHelper = null;
+
+            // Act
+            _api.InitQueryHelper(out queryHelper, maxCount);
+
+            // Assert
+            Assert.IsNotNull(queryHelper);
+            Assert.AreEqual(queryHelper.QueryMaxResults, maxCount);
+        }
+
+        [Test]
+        public void ModifyQueryHelper_ShouldSetQueryHelper_WhenPatternIsAsterisk()
+        {
+            // Arrange
+            ISearchQueryHelper queryHelper;
+            String pattern = "*";
+            _api.InitQueryHelper(out queryHelper, 10);
+
+            // Act
+            _api.ModifyQueryHelper(ref queryHelper, pattern);
+
+            // Assert
+            Assert.IsFalse(queryHelper.QueryWhereRestrictions.Contains("LIKE"));
+            Assert.IsFalse(queryHelper.QueryWhereRestrictions.Contains("Contains"));
+        }
+
+        [Test]
+        public void ModifyQueryHelper_ShouldSetQueryHelper_WhenPatternContainsAsterisk()
+        {
+            // Arrange
+            ISearchQueryHelper queryHelper;
+            String pattern = "tt*^&)";
+            _api.InitQueryHelper(out queryHelper, 10);
+
+            // Act
+            _api.ModifyQueryHelper(ref queryHelper, pattern);
+
+            // Assert
+            Assert.IsTrue(queryHelper.QueryWhereRestrictions.Contains("LIKE"));
+            Assert.IsFalse(queryHelper.QueryWhereRestrictions.Contains("Contains"));
+        }
+
+        [Test]
+        public void ModifyQueryHelper_ShouldSetQueryHelper_WhenPatternContainsPercent()
+        {
+            // Arrange
+            ISearchQueryHelper queryHelper;
+            String pattern = "tt%^&)";
+            _api.InitQueryHelper(out queryHelper, 10);
+
+            // Act
+            _api.ModifyQueryHelper(ref queryHelper, pattern);
+
+            // Assert
+            Assert.IsTrue(queryHelper.QueryWhereRestrictions.Contains("LIKE"));
+            Assert.IsFalse(queryHelper.QueryWhereRestrictions.Contains("Contains"));
+        }
+
+        [Test]
+        public void ModifyQueryHelper_ShouldSetQueryHelper_WhenPatternContainsUnderScore()
+        {
+            // Arrange
+            ISearchQueryHelper queryHelper;
+            String pattern = "tt_^&)";
+            _api.InitQueryHelper(out queryHelper, 10);
+
+            // Act
+            _api.ModifyQueryHelper(ref queryHelper, pattern);
+
+            // Assert
+            Assert.IsTrue(queryHelper.QueryWhereRestrictions.Contains("LIKE"));
+            Assert.IsFalse(queryHelper.QueryWhereRestrictions.Contains("Contains"));
+        }
+
+        [Test]
+        public void ModifyQueryHelper_ShouldSetQueryHelper_WhenPatternContainsQuestionMark()
+        {
+            // Arrange
+            ISearchQueryHelper queryHelper;
+            String pattern = "tt?^&)";
+            _api.InitQueryHelper(out queryHelper, 10);
+
+            // Act
+            _api.ModifyQueryHelper(ref queryHelper, pattern);
+
+            // Assert
+            Assert.IsTrue(queryHelper.QueryWhereRestrictions.Contains("LIKE"));
+            Assert.IsFalse(queryHelper.QueryWhereRestrictions.Contains("Contains"));
+        }
+
+        [Test]
+        public void ModifyQueryHelper_ShouldSetQueryHelper_WhenPatternDoesNotContainSplSymbols()
+        {
+            // Arrange
+            ISearchQueryHelper queryHelper;
+            String pattern = "tt^&)bc";
+            _api.InitQueryHelper(out queryHelper, 10);
+
+            // Act
+            _api.ModifyQueryHelper(ref queryHelper, pattern);
+
+            // Assert
+            Assert.IsFalse(queryHelper.QueryWhereRestrictions.Contains("LIKE"));
+            Assert.IsTrue(queryHelper.QueryWhereRestrictions.Contains("Contains"));
+        }
+
+        [Test]
+        public void ExecuteQuery_ShouldDisposeAllConnections_AfterFunctionCall()
+        {
+            // Arrange
+            ISearchQueryHelper queryHelper;
+            _api.InitQueryHelper(out queryHelper, 10);
+            _api.ModifyQueryHelper(ref queryHelper, "*");
+            string keyword = "test";
+
+            // Act
+            _api.ExecuteQuery(queryHelper, keyword);
+
+            // Assert
+            Assert.IsNull(_api.conn);
+            Assert.IsNull(_api.command);
+            Assert.IsNull(_api.WDSResults);
+        }
+    }
+}
diff --git a/src/modules/launcher/Wox.Test/Wox.Test.csproj b/src/modules/launcher/Wox.Test/Wox.Test.csproj
index 1de1a7880b..e656fca226 100644
--- a/src/modules/launcher/Wox.Test/Wox.Test.csproj
+++ b/src/modules/launcher/Wox.Test/Wox.Test.csproj
@@ -38,6 +38,7 @@
   <ItemGroup>
     <Reference Include="System" />
     <Reference Include="System.Core" />
+    <Reference Include="System.Data" />
   </ItemGroup>
   <ItemGroup>
     <Compile Include="..\SolutionAssemblyInfo.cs">
@@ -45,10 +46,15 @@
     </Compile>
     <Compile Include="FuzzyMatcherTest.cs" />
     <Compile Include="Plugins\PluginInitTest.cs" />
+    <Compile Include="Plugins\WindowsIndexerTest.cs" />
     <Compile Include="QueryBuilderTest.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>
   <ItemGroup>
+    <ProjectReference Include="..\Plugins\Wox.Plugin.Indexer\Wox.Plugin.Indexer.csproj">
+      <Project>{63c3cea8-51fe-472e-b97c-b58f8b17dd51}</Project>
+      <Name>Wox.Plugin.Indexer</Name>
+    </ProjectReference>
     <ProjectReference Include="..\Wox.Core\Wox.Core.csproj">
       <Project>{B749F0DB-8E75-47DB-9E5E-265D16D0C0D2}</Project>
       <Name>Wox.Core</Name>
@@ -72,6 +78,9 @@
     <PackageReference Include="NUnit3TestAdapter">
       <Version>3.15.1</Version>
     </PackageReference>
+    <PackageReference Include="tlbimp-Microsoft.Search.Interop">
+      <Version>1.0.0</Version>
+    </PackageReference>
   </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it.