docs: document dotnet coverage workflow (#2409)

Author: rogeralsing

README.md

@@ -35,8 +35,57 @@ Additional root-level documents provide deeper insights into the project:
 - [EVENTSTREAM_EVENTS.md](EVENTSTREAM_EVENTS.md) – lists key EventStream events and their publishers/subscribers.
 - [SECURITY.md](SECURITY.md) – security policy and supported versions.
 - [Terminology.md](Terminology.md) – definitions of common Proto.Actor terms.
-
-## Design principles
+
+## Test coverage
+
+You can capture code coverage directly when running the test projects. The .NET SDK ships an `XPlat Code Coverage` data collector that works across platforms, so you do not need any third-party tooling for the basic workflow.
+
+### Quick coverage run
+
+Run any test project with coverage enabled by passing the `CollectCoverage` property:
+
+```bash
+dotnet test /p:CollectCoverage=true
+```
+
+This uses the built-in collector and writes coverage data under the `TestResults` directory for the invocation.
+
+### Using coverlet.collector
+
+For richer reporting support you can opt into the `coverlet.collector` package. Add it to the test project you want to analyze:
+
+```bash
+dotnet add package coverlet.collector
+```
+
+Then request coverage when running the tests:
+
+```bash
+dotnet test --collect:"XPlat Code Coverage"
+```
+
+This produces a `.coverage` file under `TestResults/...` that can be converted into other formats.
+
+### Alternative output formats
+
+You can ask the collector to emit other formats such as Cobertura, lcov, or OpenCover. For example, to produce an `lcov` report:
+
+```bash
+dotnet test --collect:"XPlat Code Coverage" -- DataCollectionRunSettings.DataCollectors.DataCollector.Configuration.Format=lcov
+```
+
+### HTML reports
+
+Feed the generated `lcov` or `cobertura` files into tools like [ReportGenerator](https://github.com/danielpalme/ReportGenerator) to build browsable HTML output. Install the global tool and point it at your coverage reports:
+
+```bash
+dotnet tool install -g dotnet-reportgenerator-globaltool
+reportgenerator -reports:**/coverage.cobertura.xml -targetdir:coveragereport
+```
+
+Open the files in the `coveragereport` directory to inspect the results.
+
+## Design principles
 
 **Minimalistic API** - The API should be small and easy to use. Avoid enterprisey containers and configurations.
 

context.md

@@ -1,7 +1,7 @@
 # Repository Root Context
 
 ## Overview
-Root of the Proto.Actor for .NET repository. Hosts the runtime, clustering, remote communication, persistence providers, tooling, tests, and numerous samples.
+Root of the Proto.Actor for .NET repository. Hosts the runtime, clustering, remote communication, persistence providers, tooling, tests, and numerous samples. The `README.md` document also summarizes how to collect code coverage with the .NET SDK for contributors verifying their changes.
 
 Start here, but also read [`README.md`](README.md) for project onboarding, then dive into [`src/context.md`](src/context.md), [`tests/context.md`](tests/context.md), and [`examples/context.md`](examples/context.md) for subsystem-specific guides.