Debugging the NUnit3TestAdapter

Enable Tracing

Before debugging the adapter, check the trace outputs, which can be enabled using runsettings, either from a file or the command line.

Enable the following features:

    <DumpXmlTestDiscovery>true</DumpXmlTestDiscovery>
    <DumpXmlTestResults>true</DumpXmlTestResults>

This will create a Dump folder under the executing bin directory, containing one file for each setting. These files include both the input from the testhost and the resulting data returned by the framework/engine.

Enabling debugging

Debugging the adapter is done by first creating a debug version of the adapter. You can then enable a debug run by passing one of the NUnit debug settings using runsettings.

The symbols are:

NUnit.DebugExecution
NUnit.DebugDiscovery
NUnit.Debug
NUnit.DebugEngine  # (From version 6.1)

The NUnit.Debug is equal to setting both of the two above.

The NUnit.DebugEngine enables debugging of the embedded NUnit.Engine.

From command line, you can set these by adding e.g.

dotnet test -- NUnit.DebugExecution=true

If you want to do this using Visual Studio, you must add a runsettings file, and add these settings there to the NUnit section.

A detailed explanation of the process can be found in this blog post

Debugging earlier versions

See this blog post for details on that process.