[Scala3][WIP] Scala3 testing I by adkian-sifive · Pull Request #5083 · chipsalliance/chisel

adkian-sifive · 2025-11-25T00:27:47Z

Move spec files from src/test/scala-2 to src/test/scala/ and update for cross-compilation with Scala 3.

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Did you add Scaladoc to every public function/method?
Did you add at least one test demonstrating the PR?
Did you delete any extraneous printlns/debugging code?
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Feature (or new API)
API modification
API deprecation
Backend code generation
Performance improvement
Bugfix
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Dependency update
Internal or build-related (includes code refactoring/cleanup)

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Rebase: You will rebase the PR onto master and it will be merged with a merge commit.

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seldridge

Generally LGTM. Some nits and there are some issues with CI.

seldridge · 2025-11-25T03:34:24Z

src/test/scala-2/chiselTests/simulator/SimulatorSpec.scala

 import org.scalatest.funspec.AnyFunSpec
 import org.scalatest.matchers.must.Matchers
-import org.scalatest.matchers.should.Matchers.convertToAnyShouldWrapper
+// import org.scalatest.matchers.should.Matchers.convertToStringShouldWrapperForVerb


Nit: please don't commit commented out code.

yeah this is a tricky one. the scalatest API is subtly different between Scala 2 and 3 leading to an either-or situation as to which ShouldWrapper to use. will revisit and fix

Please check that ScalaTest doesn't already have a way to deal with this--it would be pretty bush league for such a popular library to screw this up. If they dont then we can polyfill it ourselves by adding a type alias for one or the other in the version-specific sources (e.g. in src/main/scala-2 define org.scalatest.matchers.should.Matchers.convertToStringShouldWrapperForVerb as a type alias for org.scalatest.matchers.should.Matchers.convertToAnyShouldWrapper).

This still needs resolution

src/test/scala/chiselTests/AutoNestedCloneSpec.scala

seldridge · 2025-11-25T03:35:55Z

src/test/scala/chiselTests/SimLogSpec.scala

      val in = IO(Input(UInt(8.W)))
      val fd = SimLog.file("logfile.log")
-      fd.printf("in = %d\n", in)
+      // fd.printf("in = %d\n", in)


I think this shouldn't be commented out?

seldridge · 2025-11-25T03:36:42Z

src/test/scala/chiselTests/UIntOps.scala

I'm surprised this file has so many lines added. Can you clarify what is going on?

jackkoenig · 2026-01-17T17:07:43Z

src/test/scala-2/chiselTests/stage/ChiselStageSpec.scala

+    implicit val info: SourceLine = SourceLine("Foo", 3, 10)
    3.U >> -1
  }

  class ErrorCaughtByFirtool extends RawModule {
-    implicit val info = SourceLine("Foo", 3, 10)
+    implicit val info: SourceLine = SourceLine("Foo", 3, 10)


These should be the more generic type SourceInfo, not the specific type.

jackkoenig · 2026-01-17T17:08:05Z

src/test/scala-2/chiselTests/simulator/SimulatorSpec.scala

 import org.scalatest.funspec.AnyFunSpec
 import org.scalatest.matchers.must.Matchers
-import org.scalatest.matchers.should.Matchers.convertToAnyShouldWrapper
+// import org.scalatest.matchers.should.Matchers.convertToStringShouldWrapperForVerb


This still needs resolution

jackkoenig · 2026-01-17T17:09:55Z

src/test/scala-2/chiselTests/experimental/OpaqueTypeSpec.scala

    lazy val elements = SeqMap("" -> gen)
-    def underlying = elements.head._2
+    def underlying = elements.head._2.asInstanceOf[T]


Better for both of these would be:

val underlying = gen lazy val elements = SeqMap("" -> underlying)

It's not that this is fundamentally wrong, but people do look at the tests to get inspiration or see best practice sometimes and this cast is not good practice.

jackkoenig · 2026-01-17T17:10:31Z

src/test/scala/chiselTests/naming/PrefixSpec.scala

@@ -3,7 +3,6 @@
 package chiselTests.naming

 import chisel3._
-import chisel3.aop.Select


If these aren't used, I'm all for deleting (and we should eventually enable scalafix to do it for us), but why did this need to be deleted to run the test with Scala 3?

jackkoenig · 2026-01-17T17:11:05Z

src/test/scala/chiselTests/AdderTree.scala

  dut.io.numIn := VecInit(numsToAdd.map(x => x.asUInt(bitWidth.W)))
  val sumCorrect = dut.io.numOut === (numsToAdd.reduce(_ + _) % (1 << bitWidth)).asUInt(bitWidth.W)
-  assert(sumCorrect)
+  chisel3.assert(sumCorrect)


Why is this necessary?

jackkoenig · 2026-01-17T17:15:15Z

src/test/scala/chiselTests/BlackBox.scala

      final val io = IO {
        new Bundle {
-          val a = Output(probe.Probe(Bool(), layers.Verification))
+          val a = Output(probe.Probe(Bool(), chisel3.layers.Verification))


I'm confused by why these are needed

jackkoenig · 2026-01-17T17:15:48Z

src/test/scala/chiselTests/BulkConnectSpec.scala


      @nowarn("cat=deprecation")
-      val bb = Module(new BlackBox {
+      val bb = Module[BlackBox { def io: MyBundle }](new BlackBox {


This should not be necessary due to Selectable right? Or did we decide not to apply that to modules?

jackkoenig · 2026-01-17T17:19:38Z

src/test/scala/chiselTests/ModuleChoiceSpec.scala

    extends Module {
-  val inst = ModuleChoice(default)(alternateImpls)
-  val io = IO(inst.cloneType)
+  val inst: T = ModuleChoice[T](default, alternateImpls)


This is wrong, the API in src/main/scala-3/chisel3/choice/ModuleChoiceIntf.scala is incorrect and should be changed to match that in src/main/scala-2

adkian-sifive force-pushed the adkian-sifive/scala3-testing-I branch 2 times, most recently from fa56dfd to 2e3d722 Compare November 25, 2025 00:32

adkian-sifive added the Scala 3 Changes related to upgrading to Scala 3 label Nov 25, 2025

seldridge reviewed Nov 25, 2025

View reviewed changes

adkian-sifive force-pushed the adkian-sifive/scala3-testing-I branch 3 times, most recently from a482a98 to 85ad8fa Compare November 25, 2025 22:26

adkian-sifive force-pushed the adkian-sifive/scala3-testing-I branch 2 times, most recently from 7326a10 to 1920295 Compare January 13, 2026 21:54

adkian-sifive added 13 commits January 16, 2026 15:57

move files over

e68ee03

Remove structural types from UIntOps and SIntOps

c25938a

Move back unsupported files

9ecf4c7

Move back unsupported files

26f4642

Move BoringUtilsSpec to scala-2

8da5e1d

Add and update files

9e1153e

Scalafmt

6475b20

Move ComplexAssign back

ac62454

Move back OpaqueTypeSpec

d42f190

Move back Direction.scala

c3dec70

Move back InstanceNameSpec

49a7fbf

Test updates

c60d031

Remove reflectiveSelectable import

f12ce6d

adkian-sifive force-pushed the adkian-sifive/scala3-testing-I branch from 1920295 to f12ce6d Compare January 16, 2026 23:57

jackkoenig reviewed Jan 17, 2026

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adkian-sifive commented Nov 25, 2025

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