Add unit tests for SingleInstanceHelper and fix formatting from simplifying PR #11863

src/Microsoft.VisualBasic.Forms/src/Microsoft/VisualBasic/ApplicationServices/SingleInstanceHelpers.vb

@@ -12,20 +12,26 @@ Namespace Microsoft.VisualBasic.ApplicationServices
     Friend Module SingleInstanceHelpers
         Private Const NamedPipeOptions As PipeOptions = PipeOptions.Asynchronous Or PipeOptions.CurrentUserOnly
 
-        Private Async Function ReadArgsAsync(pipeServer As NamedPipeServerStream, cancellationToken As CancellationToken) As Task(Of String())
+        Private Async Function ReadArgsAsync(
+            pipeServer As NamedPipeServerStream,
+            cancellationToken As CancellationToken) As Task(Of String())
+
             Const bufferLength As Integer = 1024
-            Dim buffer As Byte() = New Byte(bufferLength - 1) {}
+
             Using stream As New MemoryStream
                 While True
+                    Dim buffer As Byte() = New Byte(bufferLength - 1) {}
                     Dim bytesRead As Integer = Await pipeServer.ReadAsync(
-                        buffer.AsMemory(0, bufferLength),
-                        cancellationToken).ConfigureAwait(False)
+                        buffer:=buffer.AsMemory(start:=0, length:=bufferLength),
+                        cancellationToken) _
+                            .ConfigureAwait(continueOnCapturedContext:=False)
                     If bytesRead = 0 Then
                         Exit While
                     End If
                     Await stream.WriteAsync(
-                        buffer.AsMemory(0, bytesRead),
-                        cancellationToken).ConfigureAwait(False)
+                        buffer:=buffer.AsMemory(start:=0, length:=bytesRead),
+                        cancellationToken) _
+                            .ConfigureAwait(continueOnCapturedContext:=False)
                 End While
                 stream.Seek(0, SeekOrigin.Begin)
                 Dim serializer As New DataContractSerializer(GetType(String()))
@@ -37,48 +43,70 @@ Namespace Microsoft.VisualBasic.ApplicationServices
             End Using
         End Function
 
-        Private Async Function WriteArgsAsync(pipeClient As NamedPipeClientStream, args As String(), cancellationToken As CancellationToken) As Task
+        Private Async Function WriteArgsAsync(
+            pipeClient As NamedPipeClientStream,
+            args As String(),
+            cancellationToken As CancellationToken) As Task
+
             Dim content As Byte()
             Using stream As New MemoryStream
                 Dim serializer As New DataContractSerializer(GetType(String()))
                 serializer.WriteObject(stream, args)
                 content = stream.ToArray()
             End Using
-            Await pipeClient.WriteAsync(content.AsMemory(0, content.Length), cancellationToken).ConfigureAwait(False)
+            Await pipeClient.WriteAsync(
+                buffer:=content.AsMemory(start:=0, length:=content.Length), cancellationToken) _
+                    .ConfigureAwait(continueOnCapturedContext:=False)
         End Function
 
-        Friend Async Function SendSecondInstanceArgsAsync(pipeName As String, args As String(), cancellationToken As CancellationToken) As Task
+        Friend Async Function SendSecondInstanceArgsAsync(
+            pipeName As String,
+            args As String(),
+            cancellationToken As CancellationToken) As Task
+
             Using pipeClient As New NamedPipeClientStream(
-                            serverName:=".",
-                            pipeName:=pipeName,
-                            direction:=PipeDirection.Out,
-                            options:=NamedPipeOptions)
-                Await pipeClient.ConnectAsync(cancellationToken).ConfigureAwait(False)
-                Await WriteArgsAsync(pipeClient, args, cancellationToken).ConfigureAwait(False)
+                serverName:=".",
+                pipeName:=pipeName,
+                direction:=PipeDirection.Out,
+                options:=NamedPipeOptions)
+
+                Await pipeClient.ConnectAsync(cancellationToken) _
+                    .ConfigureAwait(continueOnCapturedContext:=False)
+                Await WriteArgsAsync(pipeClient, args, cancellationToken) _
+                    .ConfigureAwait(continueOnCapturedContext:=False)
             End Using
         End Function
 
-        Friend Function TryCreatePipeServer(pipeName As String, <Out> ByRef pipeServer As NamedPipeServerStream) As Boolean
+        Friend Function TryCreatePipeServer(
+            pipeName As String,
+            <Out> ByRef pipeServer As NamedPipeServerStream) As Boolean
+
             Try
                 pipeServer = New NamedPipeServerStream(
-                        pipeName:=pipeName,
-                        direction:=PipeDirection.In,
-                        maxNumberOfServerInstances:=1,
-                        transmissionMode:=PipeTransmissionMode.Byte,
-                        options:=NamedPipeOptions)
+                    pipeName:=pipeName,
+                    direction:=PipeDirection.In,
+                    maxNumberOfServerInstances:=1,
+                    transmissionMode:=PipeTransmissionMode.Byte,
+                    options:=NamedPipeOptions)
                 Return True
             Catch ex As Exception
                 pipeServer = Nothing
                 Return False
             End Try
         End Function
 
-        Friend Async Function WaitForClientConnectionsAsync(pipeServer As NamedPipeServerStream, callback As Action(Of String()), cancellationToken As CancellationToken) As Task
+        Friend Async Function WaitForClientConnectionsAsync(
+            pipeServer As NamedPipeServerStream,
+            callback As Action(Of String()),
+            cancellationToken As CancellationToken) As Task
+
             While True
                 cancellationToken.ThrowIfCancellationRequested()
-                Await pipeServer.WaitForConnectionAsync(cancellationToken).ConfigureAwait(False)
+                Await pipeServer.WaitForConnectionAsync(cancellationToken) _
+                    .ConfigureAwait(continueOnCapturedContext:=False)
                 Try
-                    Dim args() As String = Await ReadArgsAsync(pipeServer, cancellationToken).ConfigureAwait(False)
+                    Dim args() As String = Await ReadArgsAsync(pipeServer, cancellationToken) _
+                        .ConfigureAwait(continueOnCapturedContext:=False)
                     If args IsNot Nothing Then
                         callback(args)
                     End If

src/Microsoft.VisualBasic.Forms/tests/UnitTests/System/Windows/Forms/SingleInstanceHelpersTests.vb

@@ -0,0 +1,84 @@
+' Licensed to the .NET Foundation under one or more agreements.
+' The .NET Foundation licenses this file to you under the MIT license.
+
+Imports System.IO.Pipes
+Imports System.Runtime.CompilerServices
+Imports System.Threading
+Imports FluentAssertions
+Imports Microsoft.VisualBasic.ApplicationServices
+
+Imports Xunit
+
+Namespace Microsoft.VisualBasic.Forms.Tests
+
+    Public Class SingleInstanceHelpersTests
+        Private _resultArgs As String()
+
+        <WinFormsFact>
+        Public Sub TryCreatePipeServerTests()
+            Dim pipeName As String = GetUniqueText()
+            Dim pipeServer As NamedPipeServerStream = Nothing
+            TryCreatePipeServer(pipeName, pipeServer).Should.BeTrue()
+            Using pipeServer
+                pipeServer.CanRead.Should.BeTrue()
+                pipeServer.CanSeek.Should.BeFalse()
+                pipeServer.CanWrite.Should.BeFalse()
+                pipeServer.TransmissionMode.Should.Be(PipeTransmissionMode.Byte)
+            End Using
+        End Sub
+
+        <WinFormsFact>
+        Public Sub TryCreatePipeServerTwiceTests_Fail()
+            Dim pipeName As String = GetUniqueText()
+            Dim pipeServer As NamedPipeServerStream = Nothing
+            TryCreatePipeServer(pipeName, pipeServer).Should.BeTrue()
+            Using pipeServer
+                Dim pipeServer1 As NamedPipeServerStream = Nothing
+                TryCreatePipeServer(pipeName, pipeServer1).Should.BeFalse()
+                pipeServer1.Should.BeNull()
+            End Using
+        End Sub
+
+        <WinFormsFact>
+        Public Async Function WaitForClientConnectionsAsyncTests() As Task
+            Dim pipeName As String = GetUniqueText()
+            Dim pipeServer As NamedPipeServerStream = Nothing
+
+            If TryCreatePipeServer(pipeName, pipeServer) Then
+
+                Using pipeServer
+                    Dim tokenSource As New CancellationTokenSource()
+                    Dim commandLine As String() = {"Hello"}
+                    Dim clientConnection As Task = WaitForClientConnectionsAsync(
+                        pipeServer,
+                        callback:=Sub(args As String())
+                                      If args.Length = 1 Then
+                                          _resultArgs = commandLine
+                                      End If
+                                  End Sub,
+                        cancellationToken:=tokenSource.Token)
+
+                    Dim awaitable As ConfiguredTaskAwaitable = SendSecondInstanceArgsAsync(
+                        pipeName,
+                        args:=commandLine,
+                        cancellationToken:=tokenSource.Token) _
+                            .ConfigureAwait(continueOnCapturedContext:=False)
+
+                    awaitable.GetAwaiter().GetResult()
+                    Dim CancelToken As New CancellationToken
+                    Dim buffer As Byte() = New Byte(commandLine.Length) {}
+                    Dim count As Integer = Await pipeServer.ReadAsync(
+                        buffer:=buffer.AsMemory(start:=0, length:=commandLine.Length))
+
+                    ' Ensure the result is set
+                    Do
+                        Await Task.Delay(5)
+                    Loop Until _resultArgs IsNot Nothing
+                    _resultArgs(0).Should.Be("Hello")
+                    Await tokenSource.CancelAsync()
+                End Using
+            End If
+        End Function
+
+    End Class
+End Namespace