Compiler version
 3.7.1
 Minimized code
 https://github.com/Zuchos/scala3-scalatest-issue
 Output
 [info] com.zuchos.sandbox.SandboxTest *** ABORTED *** [info] java.lang.AbstractMethodError: Receiver class com.zuchos.sandbox.SandboxTest$$anon$1 does not define or inherit an implementation of the resolved method 'abstract com.zuchos.sandbox.BaseTest com$zuchos$sandbox$BaseTest$Fixture$$$outer()' of interface com.zuchos.sandbox.BaseTest$Fixture. 
  Expectation
 Most likely, not only the SandboxTest should be compiled here, but the class that it extends too.