Fix RefCount bugs (#2216)

* Fix crash when eager RefCount crosses min observer threshold more than once
* Make RefCount tests more comprehensive
* Fix RefCount with delayedDisconnect InvalidOperationException bugs

Also fixed some build issues:
* Fix missing TargetPlatformSdkPath (because an SDK change broke the build)
* Bump version since we already released 6.0.1
* Update integration tests to use Rx 6.0.2 preview
* Add release notes for 6.0.2

Author: idg10

Rx.NET/Documentation/ReleaseHistory/Rx.v6.md

@@ -1,5 +1,15 @@
 # Rx Release History v6.0
 
+## v6.0.2
+
+This release fixes:
+
+* [Issue #2173: "RefCount with MinObservers > 1 Behaves Unexpectedly"](https://github.com/dotnet/reactive/issues/2173)
+* [Issue #2214: "RefCount with disconnect delay and minObservers throws InvalidOperationException when resubscribing to synchronously completing source"](https://github.com/dotnet/reactive/issues/2214)
+* [Issue #2215: "RefCount with disconnect delay and minObservers disconnects prematurely if observer count drops to zero and then goes back up"](https://github.com/dotnet/reactive/issues/2215)
+
+Note: the test suite now tests on .NET 9.0. No changes were required as a result of this.
+
 ## v6.0.1
 
 This release fixes:

Rx.NET/Integration/LinuxTests/LinuxTests.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net7.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net8.0;net9.0</TargetFrameworks>
     <NoWarn>$(NoWarn);CS0618</NoWarn>
     <LangVersion>latest</LangVersion>
     <AssemblyName>Tests.System.Reactive</AssemblyName>
@@ -12,7 +12,7 @@
   <PropertyGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
     <DefineConstants>$(DefineConstants);</DefineConstants>
   </PropertyGroup>
-  <PropertyGroup Condition="'$(TargetFramework)' == 'net6.0' or '$(TargetFramework)' == 'net7.0' or '$(TargetFramework)' == 'net8.0'">
+  <PropertyGroup Condition="'$(TargetFramework)' == 'net8.0' or '$(TargetFramework)' == 'net9.0'">
     <DefineConstants>$(DefineConstants);LINUX</DefineConstants>
   </PropertyGroup>
 
@@ -28,8 +28,8 @@
     <PackageReference Include="MSTest.TestAdapter" Version="3.0.2" />
     <PackageReference Include="MSTest.TestFramework" Version="3.0.2" />
     <PackageReference Include="xunit.assert" Version="2.4.2" />
-    <PackageReference Include="System.Reactive" Version="6.0.0-preview*" />
-    <PackageReference Include="Microsoft.Reactive.Testing" Version="6.0.0-preview*" />
-    <PackageReference Include="System.Reactive.Observable.Aliases" Version="6.0.0-preview*" />
+    <PackageReference Include="System.Reactive" Version="6.0.2-preview*" />
+    <PackageReference Include="Microsoft.Reactive.Testing" Version="6.0.2-preview*" />
+    <PackageReference Include="System.Reactive.Observable.Aliases" Version="6.0.2-preview*" />
   </ItemGroup>
 </Project>

Rx.NET/Integration/WindowsDesktopTests/WindowsDesktopTests.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net6.0-windows10.0.19041;net7.0;net7.0-windows10.0.19041;net8.0;net8.0-windows10.0.19041</TargetFrameworks>
+    <TargetFrameworks>net8.0;net8.0-windows10.0.19041;net9.0;net9.0-windows10.0.19041</TargetFrameworks>
     <NoWarn>$(NoWarn);CS0618</NoWarn>
     <LangVersion>latest</LangVersion>
     <AssemblyName>Tests.System.Reactive</AssemblyName>
@@ -9,7 +9,7 @@
     <AssemblyOriginatorKeyFile>..\..\Source\ReactiveX.snk</AssemblyOriginatorKeyFile>
   </PropertyGroup>
 
-  <PropertyGroup Condition="$(TargetFramework.StartsWith('net6.0-windows')) or $(TargetFramework.StartsWith('net7.0-windows')) or $(TargetFramework.StartsWith('net8.0-windows'))">
+  <PropertyGroup Condition="$(TargetFramework.StartsWith('net8.0-windows')) or $(TargetFramework.StartsWith('net9.0-windows'))">
     <UseWPF>true</UseWPF>
     <UseWindowsForms>true</UseWindowsForms>
     <DefineConstants>$(DefineConstants);HAS_TRACE;HAS_WINRT;PREFER_ASYNC;HAS_TPL46;NO_REMOTING;HAS_WINFORMS;HAS_WPF;HAS_DISPATCHER;DESKTOPCLR;WINDOWS;CSWINRT</DefineConstants>
@@ -27,8 +27,8 @@
     <PackageReference Include="MSTest.TestAdapter" Version="3.0.2" />
     <PackageReference Include="MSTest.TestFramework" Version="3.0.2" />
     <PackageReference Include="xunit.assert" Version="2.4.2" />
-    <PackageReference Include="System.Reactive" Version="6.0.0-preview*" />
-    <PackageReference Include="Microsoft.Reactive.Testing" Version="6.0.0-preview*" />
-    <PackageReference Include="System.Reactive.Observable.Aliases" Version="6.0.0-preview*" />
+    <PackageReference Include="System.Reactive" Version="6.0.2-preview*" />
+    <PackageReference Include="Microsoft.Reactive.Testing" Version="6.0.2-preview*" />
+    <PackageReference Include="System.Reactive.Observable.Aliases" Version="6.0.2-preview*" />
   </ItemGroup>
 </Project>

Rx.NET/Integration/global.json

@@ -70,6 +70,9 @@
 
     <DefineConstants>$(DefineConstants);WINDOWS_UWP</DefineConstants>
 
+    <!-- At some point, it looks like a fully-qualified version number stopped resolving the TargetPlatformSdkPath
+         and now it only works with 10.0, so the SDK no longer sets this for us in UAP targets. -->
+    <TargetPlatformSdkPath Condition="'$(TargetPlatformSdkPath)' == ''">$([Microsoft.Build.Utilities.ToolLocationHelper]::GetPlatformSDKLocation('Windows', '10.0'))</TargetPlatformSdkPath>
   </PropertyGroup>