Add failing unit tests for #8412

src/EditorFeatures/Test2/EditorServicesTest2.vbproj

@@ -165,6 +165,7 @@
     <Compile Include="CallHierarchy\CallHierarchyTests.vb" />
     <Compile Include="Diagnostics\InMemoryAssemblyLoader.vb" />
     <Compile Include="Diagnostics\UseAutoProperty\UseAutoPropertyTests.vb" />
+    <Compile Include="Expansion\LambdaParameterExpansionTests.vb" />
     <Compile Include="GoToImplementation\GoToImplementationTests.vb" />
     <Compile Include="InteractivePaste\InteractivePasteCommandHandlerTests.vb" />
     <Compile Include="IntelliSense\CompletionRulesTests.vb" />
@@ -316,4 +317,4 @@
     <Import Project="..\..\..\build\Targets\VSL.Imports.targets" />
     <Import Project="..\..\..\build\Targets\Roslyn.Toolsets.Xunit.targets" />
   </ImportGroup>
-</Project>
+</Project>
\ No newline at end of file

src/EditorFeatures/Test2/Expansion/LambdaParameterExpansionTests.vb

+' Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+Imports System.Threading.Tasks
+
+Namespace Microsoft.CodeAnalysis.Editor.UnitTests.Expansion
+    Public Class LambdaParameterExpansionTests
+        Inherits AbstractExpansionTest
+
+        <Fact, Trait(Traits.Feature, Traits.Features.Expansion)>
+        Public Async Function TestCSharp_ExpandLambdaWithNoParameters() As Task
+            Dim input =
+<Workspace>
+    <Project Language="C#" CommonReferences="true">
+        <Document><![CDATA[
+using System;
+class C
+{
+    void M()
+    {
+        Action a = {|Expand:() => { }|};
+    }
+}
+        ]]></Document>
+    </Project>
+</Workspace>
+
+            Dim expected =
+<code>
+using System;
+class C
+{
+    void M()
+    {
+        Action a = () => { };
+    }
+}
+</code>
+
+            Await TestAsync(input, expected, expandParameter:=True)
+        End Function
+
+        <Fact, Trait(Traits.Feature, Traits.Features.Expansion)>
+        Public Async Function TestCSharp_ExpandLambdaWithSingleParameters_NoParens() As Task
+            Dim input =
+<Workspace>
+    <Project Language="C#" CommonReferences="true">
+        <Document><![CDATA[
+using System;
+class C
+{
+    void M()
+    {
+        Action<int> a = {|Expand:x => { }|};
+    }
+}
+        ]]></Document>
+    </Project>
+</Workspace>
+
+            Dim expected =
+<code><![CDATA[
+using System;
+class C
+{
+    void M()
+    {
+        Action<int> a = (System.Int32 x) => { };
+    }
+}
+]]></code>
+
+            Await TestAsync(input, expected, expandParameter:=True)
+        End Function
+
+        <Fact, Trait(Traits.Feature, Traits.Features.Expansion)>
+        Public Async Function TestCSharp_ExpandLambdaWithSingleParameters_WithParens() As Task
+            Dim input =
+<Workspace>
+    <Project Language="C#" CommonReferences="true">
+        <Document><![CDATA[
+using System;
+class C
+{
+    void M()
+    {
+        Action<int> a = {|Expand:(x) => { }|};
+    }
+}
+        ]]></Document>
+    </Project>
+</Workspace>
+
+            Dim expected =
+<code><![CDATA[
+using System;
+class C
+{
+    void M()
+    {
+        Action<int> a = (System.Int32 x) => { };
+    }
+}
+]]></code>
+
+            Await TestAsync(input, expected, expandParameter:=True)
+        End Function
+
+        <Fact, Trait(Traits.Feature, Traits.Features.Expansion)>
+        Public Async Function TestCSharp_ExpandLambdaWithTwoParameters() As Task
+            Dim input =
+<Workspace>
+    <Project Language="C#" CommonReferences="true">
+        <Document><![CDATA[
+using System;
+class C
+{
+    void M()
+    {
+        Action<int, int> a = {|Expand:(x, y) => { }|};
+    }
+}
+        ]]></Document>
+    </Project>
+</Workspace>
+
+            Dim expected =
+<code><![CDATA[
+using System;
+class C
+{
+    void M()
+    {
+        Action<int, int> a = (System.Int32 x, System.Int32 y) => { };
+    }
+}
+]]></code>
+
+            Await TestAsync(input, expected, expandParameter:=True)
+        End Function
+
+        <Fact, Trait(Traits.Feature, Traits.Features.Expansion)>
+        Public Async Function TestCSharp_ExpandLambdaWithThreearameters() As Task
+            Dim input =
+<Workspace>
+    <Project Language="C#" CommonReferences="true">
+        <Document><![CDATA[
+using System;
+class C
+{
+    void M()
+    {
+        Action<int, int, int> a = {|Expand:(x, y, z) => { }|};
+    }
+}
+        ]]></Document>
+    </Project>
+</Workspace>
+
+            Dim expected =
+<code><![CDATA[
+using System;
+class C
+{
+    void M()
+    {
+        Action<int, int, int> a = (System.Int32 x, System.Int32 y, System.Int32 z) => { };
+    }
+}
+]]></code>
+
+            Await TestAsync(input, expected, expandParameter:=True)
+        End Function
+
+    End Class
+End Namespace
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