ScalaTest discovery should ignore inner classes

[charpov]

I'm testing extensions to ScalaTest (using ScalaTest) with suites such as:

class AssertionsTests extends AnyFunSuite:
   test("assertExpr"):
      class Tests extends AnyFunSuite:
         test("success"):
            assertExpr(Seq(1, 2)):
               List(1) ::: List(2)
         test("failed"):
            assertExpr(42, ": not good"):
               40 + 1
      end Tests

      val suite = Tests()
      assert(suite.run(Some("success"), silent).succeeds())
      assert(!suite.run(Some("failed"), Args(R)).succeeds())
      R.lastEvent match
         case Some(ev: TestFailed) => assert(ev.message == "Expected 41, but got 42 : not good")
         case other                => fail(s"unexpected: $other ")

The Mill task test runs AssertionsTests, as it should, but also the inner class Tests (and counts the test "failed" as a failure).
Adding the setting def discoverTestsWithZinc = true solves the problem, but I think inner classes should always be ignored during discovery.
(Maybe it's a ScalaTest (or sbt) issue, but I find it interesting that discoverTestsWithZinc has an impact.)

[lefou]

@charpov Can you please include the required imports to make the snippet above compile?

[charpov]

Here's a self-contained example:

import org.scalatest.Args
import org.scalatest.funsuite.AnyFunSuite

class OuterTests extends AnyFunSuite:
   test("the test"):
      class InnerTests extends AnyFunSuite:
         test("inner test")(assert(2 + 2 == 5))

      val suite = InnerTests()
      assert(!suite.run(None, Args(_ => ())).succeeds())

and the corresponding output:

Running Test Class OuterTests
Running Test Class OuterTests$InnerTests$1
OuterTests:
OuterTests$InnerTests$1:
- the test
Run completed in 145 milliseconds.
Total number of tests run: 1
Suites: completed 1, aborted 0
Tests: succeeded 1, failed 0, canceled 0, ignored 0, pending 0
All tests passed.
- inner test *** FAILED ***
  org.scalatest.exceptions.TestFailedException was thrown. (OuterTests.scala:7)
Run completed in 148 milliseconds.
Total number of tests run: 1
Suites: completed 1, aborted 0
Tests: succeeded 0, failed 1, canceled 0, ignored 0, pending 0
*** 1 TEST FAILED ***
[error] T.test.testForked 1 tests failed: 
  OuterTests$InnerTests$1 inner test

and again with def discoverTestsWithZinc = true:

Running Test Class OuterTests
OuterTests:
- the test
Run completed in 127 milliseconds.
Total number of tests run: 1
Suites: completed 1, aborted 0
Tests: succeeded 1, failed 0, canceled 0, ignored 0, pending 0
All tests passed.

[lefou]

Further analysis shows, our logic didn't exclude local classes (classes defined in a method). I implemented a fix in #7131.