Target Different .Net Versions in Test Projects

This document explains how to target different .Net versions in test projects. It mainly focuses on the net48 and net8 frameworks.

Net48 Test Projects

The net48 test projects cannot reference net8 class libraries. The only way to do that, would be to convert the old project format to Microsoft.Net.Sdk format and target multiple frameworks. See Multi Target Test Projects.

Net8 Test Projects

The net8 test projects can reference net48, netstandard and net8 class libraries without any other adjustments.

Multi-Target Test Projects

A project that has the Microsoft.Net.Sdk format for its *.csproj file can target multiple frameworks. In the diagram and code snippets below, it is illustrated how we can multi-target net481 and net8.0.

• Change the *.csproj as below in order to target net8.0 and net481 frameworks.

<!-- *.csproj -->
<PropertyGroup>
  <TargetFrameworks>net8.0;net481</TargetFrameworks>
</PropertyGroup>

...

<!-- conditionaly target the net481 project -->
<ItemGroup Condition=" '$(TargetFramework)' == 'net481'">
  <ProjectReference Include="..\Net48Client\Net48Client.csproj" />
</ItemGroup>

<!-- conditionaly target the net8.0 project -->
<ItemGroup Condition=" '$(TargetFramework)' == 'net8.0'">
  <ProjectReference Include="..\Net8Client\Net8Client.csproj" />
</ItemGroup>

• Change the unit tests classes as below in order to run the corresponding code for the targeted framework, considering this:
  • The using statement needs compiler directive
  • The netstandard code does not need any compiler directive
  • The net481 and net8 code needs compiler directive

// The using section needs directives
#if !NETFRAMEWORK
using Net8Client;
#else
using Net48Client;
#endif

namespace NetMultiTargetTests;

[TestClass]
public class NetCalculatorTests
{
    // Method that runs with netstandard doesn't need any directive
    [TestMethod]
    public void NetStandard20SumTest()
    {
        Assert.AreEqual(3, new NetStandard20Calculator().Sum(1, 2));
    }


// Methods that run with net8 needs directive
#if !NETFRAMEWORK

    [TestMethod]
    public void Net8SumTest()
    {
        Assert.AreEqual(3, new Net8Calculator().Sum(1, 2));
    }

// Methods that run with net48 needs directive
#else

    [TestMethod]
    public void Net48SumTest()
    {
        Assert.AreEqual(3, new Net48Calculator().Sum(1, 2));
    }


#endif
}