Rider 2026.3 EAP: dotCover Finally Measures TUnit Coverage

JetBrains opened the Rider 2026.3 Early Access Program on September 7, 2026. The headline features are the ones that screenshot well: rainbow brackets (off by default, under Settings | Editor | General | Appearance), a filter bar in the completion popup, and a dedicated Game Development plugin category. The change that actually unblocks a repo is two sentences further down: Rider’s dotCover integration now measures coverage for unit tests written with TUnit.

Why TUnit projects reported nothing

TUnit is a Microsoft.Testing.Platform native test framework. It has no VSTest adapter, which is the whole point: the test project builds an executable that owns its own entry point and talks the MTP protocol, rather than being hosted by vstest.console. That is the same architecture shift behind the move from VSTest to Microsoft.Testing.Platform in .NET 11.

dotCover’s in-IDE coverage runner attached to the VSTest host. With no VSTest host in the picture, “Cover Unit Tests” on a TUnit project either produced an empty report or refused to start, and JetBrains tracked it as DCVR-12871. Teams that wanted numbers fell back to dotnet test --coverage with Microsoft.Testing.Extensions.CodeCoverage and read a Cobertura file, which works fine in CI and is useless when you want green and red gutters next to the line you are editing.

Turning it on

Coverage is not automatic on upgrade. Two prerequisites, both explicit in the EAP announcement.

First, the test project needs the profiler framework package:

<ItemGroup>
  <PackageReference Include="TUnit" />
  <PackageReference Include="JetBrains.dotCover.Framework" />
</ItemGroup>

Second, the platform floor is Microsoft.Testing.Platform 2.3.0 or later. That is the same 2.3.0 that shipped streaming TRX and GitHub Actions annotations in July 2026, so most repos on a current TUnit are already above the line. Check what you actually restored rather than what you declared:

dotnet list package --include-transitive | grep Microsoft.Testing.Platform

Then make sure Rider is driving MTP at all: Settings | Build, Execution, Deployment | Unit Testing | Testing Platform, and check “Enable Test Platform support”. Without that box, Rider still routes through its legacy runner and you are back to an empty report.

The other one worth the EAP risk

Data breakpoints stopped being a Watches-window ritual. You can right-click a variable in the editor and configure one there, or create one straight from the Breakpoints tool window by typing a memory address and a region size. Read and write access, conditions, and logging are all supported. For chasing a field that some other thread is stomping on, that is a materially shorter path than the old flow.

EAP builds are free while the program runs and they do expire, so treat this as a way to unblock a TUnit repo’s coverage story now rather than a machine you ship from.