Debugging tests appearing as 'Inconclusive': "Test runner agent exited unexpectedly Process ReSharperTestRunner64.exe exited with code '0'"

Problem

When attempting to debug NUnit tests using ReSharper, the tests are reported as 'Inconclusive', there is the following error in the log file:

Test runner agent exited unexpectedly Process {path}\ReSharperTestRunner64.exe:2952 exited with code '0'.

This issue does not occur when running tests without debugging.

Cause

The cause was identified to be interference from antivirus software (Avast), which prevents the ReSharper test runner from functioning correctly during a debugging session.

Resolution

To resolve this issue consider disabling antivirus software or adding an exception for ReSharper processes in the antivirus software.