Move scala2-library-tasty-tests/run tests to tests/run/scala2-library-test (#19383)

The `tests/run/scala2-library-test` test will be tested with the
original Scala 2 library JAR and with the Scala 2 library TASTy JAR
depending on the `scala2Library` SBT setting.

Author: bishabosha

.github/workflows/ci.yaml

@@ -136,7 +136,7 @@ jobs:
 
       - name: Cmd Tests
         run: |
-          ./project/scripts/sbt ";dist/pack; scala3-bootstrapped/compile; scala3-bootstrapped/test ;sbt-test/scripted scala2-compat/* ;scala2-library-tasty-tests/run ;scala2-library-tasty-tests/test; scala3-compiler-bootstrapped/scala3CompilerCoursierTest:test"
+          ./project/scripts/sbt ";dist/pack; scala3-bootstrapped/compile; scala3-bootstrapped/test ;sbt-test/scripted scala2-compat/*; scala2-library-tasty-tests/test; scala3-compiler-bootstrapped/scala3CompilerCoursierTest:test"
           ./project/scripts/cmdTests
           ./project/scripts/bootstrappedOnlyCmdTests
 
@@ -547,7 +547,7 @@ jobs:
 
       - name: Test
         run: |
-          ./project/scripts/sbt ";dist/pack ;scala3-bootstrapped/compile ;scala3-bootstrapped/test ;sbt-test/scripted scala2-compat/* ;scala2-library-tasty-tests/run ;scala2-library-tasty-tests/test"
+          ./project/scripts/sbt ";dist/pack ;scala3-bootstrapped/compile ;scala3-bootstrapped/test ;sbt-test/scripted scala2-compat/*; scala2-library-tasty-tests/test"
           ./project/scripts/cmdTests
           ./project/scripts/bootstrappedOnlyCmdTests
 

docs/_docs/contributing/testing.md

@@ -164,14 +164,7 @@ to load the TASTy and the runtime to load the original classfiles.
 
 The library is compiled in `scala2-library-bootstrapped` with TASTy and classfiles.
 These classfiles should not be used. The `scala2-library-tasty` project repackages the
-JAR `scala2-library-bootstrapped` to only keep TASTy files. The `scala2-library-tasty-tests` provides some basic tests using the library TASTy JAR.
-
-```
-$ sbt
-> scala2-library-tasty/compile
-> scala2-library-tasty-tests/run
-> scala2-library-tasty-tests/test
-```
+JAR `scala2-library-bootstrapped` to only keep TASTy files.
 
 We can enable this library in the build using the SBT setting `useScala2LibraryTasty`. This setting can only be used by bootstrapped compiler tests and is currently only supported for `test` (or `testCompilation`) and `scalac` (or `run`).
 

scala2-library-tasty-tests/src/Main.scala renamed to tests/run/scala2-library-test/Main.scala

@@ -1,12 +1,13 @@
-package hello
+// This tests language features that have a special handling in the Scala 2 library TASTy.
+// These should behave the same way from if compiled against the Scala 2 library class files ot TASTy.
 
 import scala.util.*
 import scala.compiletime.testing.typeChecks
 
 enum Color:
   case Red, Green, Blue
 
-object HelloWorld:
+object Test:
   def main(args: Array[String]): Unit = {
     println("hello 2.13 library bootstrapped")
     println(Color.Red)
@@ -74,4 +75,4 @@ object HelloWorld:
     new collection.ArrayOps[String](Array[String]("foo")).exists(x => true)
   }
 
-end HelloWorld
+end Test