diff --git a/build.mill.scala b/build.mill.scala
index 3d77168989..5a49dbf935 100644
--- a/build.mill.scala
+++ b/build.mill.scala
@@ -303,9 +303,9 @@ trait BuildMacros extends ScalaCliCrossSbtModule
     else super.compileIvyDeps() ++ Agg(Deps.scalaReflect(crossScalaVersion))
   }
 
-  object test extends ScalaCliTests {
+  object test extends ScalaCliTests with ScalaCliScalafixModule {
     override def scalacOptions: T[Seq[String]] = Task {
-      super.scalacOptions() ++ asyncScalacOptions(scalaVersion())
+      super.scalacOptions() ++ Seq("-deprecation")
     }
 
     def testNegativeCompilation(): Command[Unit] = Task.Command(exclusive = true) {
@@ -669,7 +669,8 @@ trait Options extends ScalaCliCrossSbtModule with ScalaCliPublishModule with Has
   override def repositoriesTask: Task[Seq[Repository]] =
     Task.Anon(super.repositoriesTask() ++ deps.customRepositories)
 
-  object test extends ScalaCliTests {
+  object test extends ScalaCliTests with ScalaCliScalafixModule {
+    override def scalacOptions = super.scalacOptions() ++ Seq("-deprecation")
     // uncomment below to debug tests in attach mode on 5005 port
     // def forkArgs = Task {
     //   super.forkArgs() ++ Seq("-agentlib:jdwp=transport=dt_socket,server=n,address=localhost:5005,suspend=y")
@@ -716,8 +717,9 @@ trait Build extends ScalaCliCrossSbtModule
   override def repositoriesTask: Task[Seq[Repository]] =
     Task.Anon(super.repositoriesTask() ++ deps.customRepositories)
 
-  object test extends ScalaCliTests {
-    override def ivyDeps: T[Loose.Agg[Dep]] = super.ivyDeps() ++ Agg(
+  object test extends ScalaCliTests with ScalaCliScalafixModule {
+    override def scalacOptions: T[Seq[String]] = super.scalacOptions() ++ Seq("-deprecation")
+    override def ivyDeps: T[Loose.Agg[Dep]]    = super.ivyDeps() ++ Agg(
       Deps.pprint,
       Deps.slf4jNop
     )
diff --git a/modules/build-macros/src/test/scala/scala/build/CPSTest.scala b/modules/build-macros/src/test/scala/scala/build/CPSTest.scala
index 1f1a0e638c..58cb67772c 100644
--- a/modules/build-macros/src/test/scala/scala/build/CPSTest.scala
+++ b/modules/build-macros/src/test/scala/scala/build/CPSTest.scala
@@ -1,13 +1,13 @@
 package scala.build
 
-import EitherCps._
+import scala.build.EitherCps.*
 
 class CPSTest extends munit.FunSuite {
 
   val failed1: Either[Int, String] = Left(1)
   val ok: Either[Int, String]      = Right("OK")
 
-  def checkResult(expected: Either[Int, String])(res: => Either[Int, String]) =
+  def checkResult(expected: Either[Int, String])(res: => Either[Int, String]): Unit =
     assertEquals(expected, res)
 
   test("Basic CPS test") {
diff --git a/modules/build/src/test/scala/scala/build/options/publish/VcsParseTest.scala b/modules/build/src/test/scala/scala/build/options/publish/VcsParseTest.scala
index d421b4b549..c9741c4c7b 100644
--- a/modules/build/src/test/scala/scala/build/options/publish/VcsParseTest.scala
+++ b/modules/build/src/test/scala/scala/build/options/publish/VcsParseTest.scala
@@ -3,8 +3,6 @@ package scala.build.options.publish
 import scala.build.Positioned
 import scala.build.errors.{BuildException, MalformedInputError}
 
-import munit.Assertions.assertEquals
-
 class VcsParseTest extends munit.FunSuite {
   test("valid GitHub") {
     val actual = Vcs.parse(Positioned.none("github:VirtusLab/scala-cli"))
@@ -18,24 +16,33 @@ class VcsParseTest extends munit.FunSuite {
   }
 
   test("invalid GitHub: missing /") {
-    val actual   = Vcs.parse(Positioned.none("github:scala-cli"))
-    val expected =
+    val actual: Either[BuildException, Vcs] = Vcs.parse(Positioned.none("github:scala-cli"))
+    val expected                            =
       Left(new MalformedInputError("github-vcs", "github:scala-cli", "github:org/project", Nil))
-
-    assert(actual.isInstanceOf[Left[BuildException, Vcs]])
+    assert {
+      actual match {
+        case Left(_: BuildException) => true
+        case _                       => sys.error("incorrect type")
+      }
+    }
     assertEquals(expected.toString, actual.toString)
   }
 
   test("invalid GitHub: too many /") {
-    val actual   = Vcs.parse(Positioned.none("github:github.com/VirtusLab/scala-cli"))
+    val actual: Either[BuildException, Vcs] =
+      Vcs.parse(Positioned.none("github:github.com/VirtusLab/scala-cli"))
     val expected = Left(new MalformedInputError(
       "github-vcs",
       "github:github.com/VirtusLab/scala-cli",
       "github:org/project",
       Nil
     ))
-
-    assert(actual.isInstanceOf[Left[BuildException, Vcs]])
+    assert {
+      actual match {
+        case Left(_: BuildException) => true
+        case _                       => sys.error("incorrect type")
+      }
+    }
     assertEquals(expected.toString, actual.toString)
   }
 
@@ -53,7 +60,7 @@ class VcsParseTest extends munit.FunSuite {
   }
 
   test("invalid generic: missing |") {
-    val actual = Vcs.parse(Positioned.none(
+    val actual: Either[BuildException, Vcs] = Vcs.parse(Positioned.none(
       "https://github.com/VirtusLab/scala-cli|scm:git:github.com/VirtusLab/scala-cli.git"
     ))
     val expected = Left(new MalformedInputError(
@@ -63,29 +70,44 @@ class VcsParseTest extends munit.FunSuite {
       Nil
     ))
 
-    assert(actual.isInstanceOf[Left[BuildException, Vcs]])
+    assert {
+      actual match {
+        case Left(_: BuildException) => true
+        case _                       => sys.error("incorrect type")
+      }
+    }
     assertEquals(expected.toString, actual.toString)
   }
 
   test("invalid generic: extra |") {
-    val actual   = Vcs.parse(Positioned.none("a|b|c|d"))
-    val expected =
+    val actual: Either[BuildException, Vcs] = Vcs.parse(Positioned.none("a|b|c|d"))
+    val expected                            =
       Left(new MalformedInputError("vcs", "a|b|c|d", "url|connection|developer-connection", Nil))
 
-    assert(actual.isInstanceOf[Left[BuildException, Vcs]])
+    assert {
+      actual match {
+        case Left(_: BuildException) => true
+        case _                       => sys.error("incorrect type")
+      }
+    }
     assertEquals(expected.toString, actual.toString)
   }
 
   test("invalid generic: gibberish") {
-    val actual   = Vcs.parse(Positioned.none("sfrgt pagdhn"))
-    val expected = Left(new MalformedInputError(
+    val actual: Either[BuildException, Vcs] = Vcs.parse(Positioned.none("sfrgt pagdhn"))
+    val expected                            = Left(new MalformedInputError(
       "vcs",
       "sfrgt pagdhn",
       "url|connection|developer-connection",
       Nil
     ))
 
-    assert(actual.isInstanceOf[Left[BuildException, Vcs]])
+    assert {
+      actual match {
+        case Left(_: BuildException) => true
+        case _                       => sys.error("incorrect type")
+      }
+    }
     assertEquals(expected.toString, actual.toString)
   }
 }
diff --git a/modules/build/src/test/scala/scala/build/tests/ActionableDiagnosticTests.scala b/modules/build/src/test/scala/scala/build/tests/ActionableDiagnosticTests.scala
index 8587d32d54..9e4913399a 100644
--- a/modules/build/src/test/scala/scala/build/tests/ActionableDiagnosticTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/ActionableDiagnosticTests.scala
@@ -1,27 +1,25 @@
 package scala.build.tests
 
 import com.eed3si9n.expecty.Expecty.expect
+import coursier.version.Version
 
-import scala.build.options.{BuildOptions, InternalOptions, SuppressWarningOptions}
 import scala.build.Ops.*
-import scala.build.{BuildThreads, Directories, LocalRepo}
-import scala.build.actionable.ActionablePreprocessor
-import scala.build.actionable.ActionableDiagnostic.*
 import scala.build.Position.File
-import coursier.core.Version
-
-import scala.build.errors.{BuildException, CompositeBuildException}
+import scala.build.actionable.ActionableDiagnostic.*
+import scala.build.actionable.ActionablePreprocessor
+import scala.build.options.{BuildOptions, InternalOptions, SuppressWarningOptions}
+import scala.build.{BuildThreads, Directories, LocalRepo}
 
 class ActionableDiagnosticTests extends TestUtil.ScalaCliBuildSuite {
 
-  val extraRepoTmpDir = os.temp.dir(prefix = "scala-cli-tests-actionable-diagnostic-")
-  val directories     = Directories.under(extraRepoTmpDir)
-  val baseOptions     = BuildOptions(
+  val extraRepoTmpDir: os.Path = os.temp.dir(prefix = "scala-cli-tests-actionable-diagnostic-")
+  val directories: Directories = Directories.under(extraRepoTmpDir)
+  val baseOptions              = BuildOptions(
     internal = InternalOptions(
       localRepository = LocalRepo.localRepo(directories.localRepoDir, TestLogger())
     )
   )
-  val buildThreads = BuildThreads.create()
+  val buildThreads: BuildThreads = BuildThreads.create()
 
   def path2url(p: os.Path): String = p.toIO.toURI.toURL.toString
 
diff --git a/modules/build/src/test/scala/scala/build/tests/BspServerTests.scala b/modules/build/src/test/scala/scala/build/tests/BspServerTests.scala
index 07612693ac..5a5244574d 100644
--- a/modules/build/src/test/scala/scala/build/tests/BspServerTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/BspServerTests.scala
@@ -1,13 +1,10 @@
 package scala.build.tests
 
 import com.eed3si9n.expecty.Expecty.expect
-import coursier.cache.CacheLogger
-import org.scalajs.logging.{NullLogger, Logger as ScalaJsLogger}
 
 import java.util.concurrent.TimeUnit
+
 import scala.build.Ops.*
-import scala.build.{Build, BuildThreads, Directories, GeneratedSource, LocalRepo}
-import scala.build.options.{BuildOptions, InternalOptions, Scope}
 import scala.build.bsp.{
   BspServer,
   ScalaScriptBuildServer,
@@ -16,20 +13,20 @@ import scala.build.bsp.{
   WrappedSourcesParams,
   WrappedSourcesResult
 }
+import scala.build.options.{BuildOptions, InternalOptions, Scope}
+import scala.build.{Build, BuildThreads, Directories, GeneratedSource, LocalRepo}
 import scala.collection.mutable.ArrayBuffer
 import scala.jdk.CollectionConverters.*
-import scala.build.bsp.{WrappedSourcesItem, WrappedSourcesResult}
-import scala.build.internal.ClassCodeWrapper
 
 class BspServerTests extends TestUtil.ScalaCliBuildSuite {
-  val extraRepoTmpDir = os.temp.dir(prefix = "scala-cli-tests-bsp-server-")
-  val directories     = Directories.under(extraRepoTmpDir)
-  val baseOptions     = BuildOptions(
+  val extraRepoTmpDir: os.Path = os.temp.dir(prefix = "scala-cli-tests-bsp-server-")
+  val directories: Directories = Directories.under(extraRepoTmpDir)
+  val baseOptions              = BuildOptions(
     internal = InternalOptions(
       localRepository = LocalRepo.localRepo(directories.localRepoDir, TestLogger())
     )
   )
-  val buildThreads = BuildThreads.create()
+  val buildThreads: BuildThreads = BuildThreads.create()
 
   def getScriptBuildServer(
     generatedSources: Seq[GeneratedSource],
diff --git a/modules/build/src/test/scala/scala/build/tests/BuildOptionsTests.scala b/modules/build/src/test/scala/scala/build/tests/BuildOptionsTests.scala
index 9c3ab79801..3599f07000 100644
--- a/modules/build/src/test/scala/scala/build/tests/BuildOptionsTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/BuildOptionsTests.scala
@@ -1,44 +1,32 @@
 package scala.build.tests
 
 import com.eed3si9n.expecty.Expecty.assert as expect
-import coursier.{Repositories, Repository}
+import coursier.Repositories
 import coursier.cache.FileCache
-import coursier.core.Version
 import coursier.maven.MavenRepository
+import coursier.version.Version
 import dependency.ScalaParameters
 
 import scala.build.Ops.*
 import scala.build.errors.{
   InvalidBinaryScalaVersionError,
   NoValidScalaVersionFoundError,
+  ScalaVersionError,
   UnsupportedScalaVersionError
 }
 import scala.build.internal.Constants.*
-import scala.build.internal.Regexes.scala2NightlyRegex
-import scala.build.options.{
-  BuildOptions,
-  BuildRequirements,
-  ClassPathOptions,
-  InternalOptions,
-  MaybeScalaVersion,
-  ScalaOptions,
-  ScalaVersionUtil,
-  ScalacOpt,
-  ShadowingSeq
-}
-import scala.build.{Build, BuildThreads, Directories, LocalRepo, Positioned, RepositoryUtils}
+import scala.build.internal.Regexes.{scala2NightlyRegex, scala3LtsRegex}
+import scala.build.options.*
 import scala.build.tests.util.BloopServer
+import scala.build.{Build, BuildThreads, Directories, LocalRepo, Positioned, RepositoryUtils}
 import scala.concurrent.duration.DurationInt
-import scala.build.internal.Regexes.scala3LtsRegex
-import scala.build.errors.ScalaVersionError
 
 class BuildOptionsTests extends TestUtil.ScalaCliBuildSuite {
   override def munitFlakyOK: Boolean = TestUtil.isCI
-
-  val extraRepoTmpDir = os.temp.dir(prefix = "scala-cli-tests-extra-repo-")
-  val directories     = Directories.under(extraRepoTmpDir)
-  val buildThreads    = BuildThreads.create()
-  val baseOptions     = BuildOptions(
+  val extraRepoTmpDir: os.Path       = os.temp.dir(prefix = "scala-cli-tests-extra-repo-")
+  val directories: Directories       = Directories.under(extraRepoTmpDir)
+  val buildThreads: BuildThreads     = BuildThreads.create()
+  val baseOptions                    = BuildOptions(
     internal = InternalOptions(
       localRepository = LocalRepo.localRepo(directories.localRepoDir, TestLogger()),
       keepDiagnostics = true
@@ -64,7 +52,7 @@ class BuildOptionsTests extends TestUtil.ScalaCliBuildSuite {
         scalaVersion = Some(MaybeScalaVersion("3.nightly"))
       )
     )
-    val scalaParams = options.scalaParams.orThrow.getOrElse(???)
+    val scalaParams = options.scalaParams.orThrow.getOrElse(sys.error("should not happen"))
     assert(
       scalaParams.scalaVersion.startsWith("3") && scalaParams.scalaVersion.endsWith("-NIGHTLY"),
       "-S 3.nightly argument does not lead to scala3 nightly build option"
@@ -76,7 +64,7 @@ class BuildOptionsTests extends TestUtil.ScalaCliBuildSuite {
         scalaVersion = Some(MaybeScalaVersion("3.1.nightly"))
       )
     )
-    val scalaParams = options.scalaParams.orThrow.getOrElse(???)
+    val scalaParams = options.scalaParams.orThrow.getOrElse(sys.error("should not happen"))
     expect(
       scalaParams.scalaVersion.startsWith("3.1.") && scalaParams.scalaVersion.endsWith("-NIGHTLY"),
       "-S 3.1.nightly argument does not lead to scala 3.1. nightly build option"
@@ -181,7 +169,7 @@ class BuildOptionsTests extends TestUtil.ScalaCliBuildSuite {
         scalaVersion = Some(MaybeScalaVersion("3.1.2-RC1"))
       )
     )
-    val scalaParams = options.scalaParams.orThrow.getOrElse(???)
+    val scalaParams = options.scalaParams.orThrow.getOrElse(sys.error("should not happen"))
     assert(
       scalaParams.scalaVersion == "3.1.2-RC1",
       "-S 3.1.2-RC1 argument does not lead to 3.1.2-RC1 build option"
@@ -224,7 +212,7 @@ class BuildOptionsTests extends TestUtil.ScalaCliBuildSuite {
         scalaVersion = Some(MaybeScalaVersion("2.nightly"))
       )
     )
-    val scalaParams = options.scalaParams.orThrow.getOrElse(???)
+    val scalaParams = options.scalaParams.orThrow.getOrElse(sys.error("should not happen"))
     assert(
       scala2NightlyRegex.unapplySeq(scalaParams.scalaVersion).isDefined,
       "-S 2.nightly argument does not lead to scala2 nightly build option"
@@ -237,7 +225,7 @@ class BuildOptionsTests extends TestUtil.ScalaCliBuildSuite {
         scalaVersion = Some(MaybeScalaVersion("2.13.nightly"))
       )
     )
-    val scalaParams = options.scalaParams.orThrow.getOrElse(???)
+    val scalaParams = options.scalaParams.orThrow.getOrElse(sys.error("should not happen"))
     assert(
       scala2NightlyRegex.unapplySeq(scalaParams.scalaVersion).isDefined,
       "-S 2.13.nightly argument does not lead to scala2 nightly build option"
@@ -250,7 +238,7 @@ class BuildOptionsTests extends TestUtil.ScalaCliBuildSuite {
         scalaVersion = Some(MaybeScalaVersion("3.lts"))
       )
     )
-    val scalaParams = options.scalaParams.orThrow.getOrElse(???)
+    val scalaParams = options.scalaParams.orThrow.getOrElse(sys.error("should not happen"))
     assert(
       scala3LtsRegex.unapplySeq(scalaParams.scalaVersion).isDefined,
       "-S 3.lts argument does not lead to scala3 LTS"
@@ -263,7 +251,7 @@ class BuildOptionsTests extends TestUtil.ScalaCliBuildSuite {
         scalaVersion = Some(MaybeScalaVersion("2.12.nightly"))
       )
     )
-    val scalaParams = options.scalaParams.orThrow.getOrElse(???)
+    val scalaParams = options.scalaParams.orThrow.getOrElse(sys.error("should not happen"))
     assert(
       scala2NightlyRegex.unapplySeq(scalaParams.scalaVersion).isDefined,
       "-S 2.12.nightly argument does not lead to scala2 nightly build option"
@@ -276,7 +264,7 @@ class BuildOptionsTests extends TestUtil.ScalaCliBuildSuite {
         scalaVersion = Some(MaybeScalaVersion("2.13.9-bin-4505094"))
       )
     )
-    val scalaParams = options.scalaParams.orThrow.getOrElse(???)
+    val scalaParams = options.scalaParams.orThrow.getOrElse(sys.error("should not happen"))
     assert(
       scalaParams.scalaVersion == "2.13.9-bin-4505094",
       "-S 2.13.9-bin-4505094 argument does not lead to 2.13.9-bin-4505094 scala version in build option"
@@ -292,7 +280,7 @@ class BuildOptionsTests extends TestUtil.ScalaCliBuildSuite {
     )
   }
 
-  val expectedScalaVersions = Seq(
+  val expectedScalaVersions: Seq[(Option[String], String)] = Seq(
     None           -> defaultScalaVersion,
     Some("2.13.2") -> "2.13.2",
     Some("3.0.1")  -> "3.0.1",
@@ -311,7 +299,7 @@ class BuildOptionsTests extends TestUtil.ScalaCliBuildSuite {
           cache = Some(FileCache().withTtl(0.seconds))
         )
       )
-      val scalaParams = options.scalaParams.orThrow.getOrElse(???)
+      val scalaParams = options.scalaParams.orThrow.getOrElse(sys.error("should not happen"))
 
       val expectedScalaParams = ScalaParameters(expectedScalaVersion)
 
@@ -375,7 +363,7 @@ class BuildOptionsTests extends TestUtil.ScalaCliBuildSuite {
       testDescription =
         s"-S $prefix should choose the $expectedVersionDescription version ($expectedVersion), not necessarily the latest stable ($latestMatchingVersion) $launcherDefaultVersionDescription"
     } test(testDescription) {
-      val scalaParams = options.scalaParams.orThrow.getOrElse(???)
+      val scalaParams = options.scalaParams.orThrow.getOrElse(sys.error("should not happen"))
 
       val expectedScalaParams = ScalaParameters(expectedVersion)
 
diff --git a/modules/build/src/test/scala/scala/build/tests/BuildProjectTests.scala b/modules/build/src/test/scala/scala/build/tests/BuildProjectTests.scala
index 6a481dfaa7..6657cc5938 100644
--- a/modules/build/src/test/scala/scala/build/tests/BuildProjectTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/BuildProjectTests.scala
@@ -3,66 +3,54 @@ package scala.build.tests
 import bloop.rifle.BloopRifleLogger
 import com.eed3si9n.expecty.Expecty.expect
 import coursier.cache.CacheLogger
-import org.scalajs.logging.{NullLogger, Logger as ScalaJsLogger}
+import org.scalajs.logging.{Logger as ScalaJsLogger, NullLogger}
 
 import java.io.PrintStream
+
 import scala.build.Ops.*
-import scala.build.errors.{BuildException, Diagnostic, Severity}
+import scala.build.errors.{BuildException, Diagnostic}
 import scala.build.input.Inputs
 import scala.build.internals.FeatureType
-import scala.build.options.{
-  BuildOptions,
-  InternalOptions,
-  JavaOptions,
-  ScalaOptions,
-  ScalacOpt,
-  Scope,
-  ShadowingSeq
-}
-import scala.build.{Build, LocalRepo, Logger, Position, Positioned, Sources}
+import scala.build.options.{BuildOptions, InternalOptions, Scope}
+import scala.build.{Build, LocalRepo, Logger, Sources}
 
 class BuildProjectTests extends TestUtil.ScalaCliBuildSuite {
 
   class LoggerMock extends Logger {
-
-    var diagnostics: List[Diagnostic] = Nil
-
-    override def error(message: String): Unit = ???
-
-    override def message(message: => String): Unit = ???
-
-    override def log(s: => String): Unit = ???
-
-    override def log(s: => String, debug: => String): Unit = ???
-
-    override def debug(s: => String): Unit = {}
-
-    override def log(diagnostics: Seq[Diagnostic]): Unit = {
+    var diagnostics: List[Diagnostic]                      = Nil
+    override def error(message: String): Unit              = sys.error(message)
+    override def message(message: => String): Unit         = System.err.println(message)
+    override def log(s: => String): Unit                   = System.err.println(s)
+    override def log(s: => String, debug: => String): Unit = System.err.println(s)
+    override def debug(s: => String): Unit                 = System.err.println(s)
+    override def log(diagnostics: Seq[Diagnostic]): Unit   = {
       this.diagnostics = this.diagnostics ++ diagnostics
     }
-
-    override def log(ex: BuildException): Unit   = {}
-    override def debug(ex: BuildException): Unit = {}
-
-    override def exit(ex: BuildException): Nothing = ???
-
-    override def coursierLogger(message: String): CacheLogger = CacheLogger.nop
-
-    override def bloopRifleLogger: BloopRifleLogger = BloopRifleLogger.nop
-    override def scalaJsLogger: ScalaJsLogger       = NullLogger
-
+    override def log(ex: BuildException): Unit = {
+      ex.printStackTrace()
+      System.err.println(ex.message)
+    }
+    override def debug(ex: BuildException): Unit = {
+      ex.printStackTrace()
+      System.err.println(ex.message)
+    }
+    override def exit(ex: BuildException): Nothing = {
+      ex.printStackTrace()
+      System.err.println(ex.message)
+      sys.exit(1)
+    }
+    override def coursierLogger(message: String): CacheLogger          = CacheLogger.nop
+    override def bloopRifleLogger: BloopRifleLogger                    = BloopRifleLogger.nop
+    override def scalaJsLogger: ScalaJsLogger                          = NullLogger
     override def scalaNativeTestLogger: scala.scalanative.build.Logger =
       scala.scalanative.build.Logger.nullLogger
-
     override def scalaNativeCliInternalLoggerOptions: List[String] =
       List()
-
-    override def compilerOutputStream: PrintStream = ???
-
-    override def verbosity = ???
-
-    override def experimentalWarning(featureName: String, featureType: FeatureType): Unit = ???
-    override def flushExperimentalWarnings: Unit                                          = ???
+    override def compilerOutputStream: PrintStream = System.out
+    override def verbosity: Int                    = 0
+    override def experimentalWarning(featureName: String, featureType: FeatureType): Unit =
+      System.err.println(s"experimental: $featureName")
+    override def flushExperimentalWarnings: Unit = ()
   }
 
   test("workspace for bsp") {
diff --git a/modules/build/src/test/scala/scala/build/tests/BuildTests.scala b/modules/build/src/test/scala/scala/build/tests/BuildTests.scala
index 6a732fdece..867f93f3d8 100644
--- a/modules/build/src/test/scala/scala/build/tests/BuildTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/BuildTests.scala
@@ -1,47 +1,38 @@
 package scala.build.tests
 
 import bloop.config.Config.LinkerMode
+import bloop.rifle.BloopRifleConfig
 import ch.epfl.scala.bsp4j
 import com.eed3si9n.expecty.Expecty.expect
 import com.google.gson.Gson
-import coursier.cache.ArtifactError
 import dependency.parser.DependencyParser
 
 import java.io.IOException
+
 import scala.build.Ops.*
 import scala.build.errors.{
   DependencyFormatError,
   InvalidBinaryScalaVersionError,
   ScalaNativeCompatibilityError
 }
-import scala.build.options.{
-  BuildOptions,
-  InternalOptions,
-  JavaOpt,
-  MaybeScalaVersion,
-  ScalaJsMode,
-  ScalacOpt,
-  ScriptOptions,
-  ShadowingSeq
-}
+import scala.build.options.*
 import scala.build.tastylib.TastyData
 import scala.build.tests.TestUtil.*
 import scala.build.tests.util.BloopServer
 import scala.build.{Build, BuildThreads, Directories, LocalRepo, Positioned}
+import scala.jdk.CollectionConverters.*
 import scala.meta.internal.semanticdb.TextDocuments
 import scala.util.Properties
-import scala.jdk.CollectionConverters.*
 
 abstract class BuildTests(server: Boolean) extends TestUtil.ScalaCliBuildSuite {
   private def hasDiagnostics = server
 
-  val buildThreads   = BuildThreads.create()
-  def bloopConfigOpt =
-    if (server) Some(BloopServer.bloopConfig)
-    else None
+  val buildThreads: BuildThreads               = BuildThreads.create()
+  def bloopConfigOpt: Option[BloopRifleConfig] =
+    if server then Some(BloopServer.bloopConfig) else None
 
-  val extraRepoTmpDir = os.temp.dir(prefix = "scala-cli-tests-extra-repo-")
-  val directories     = Directories.under(extraRepoTmpDir)
+  val extraRepoTmpDir: os.Path = os.temp.dir(prefix = "scala-cli-tests-extra-repo-")
+  val directories: Directories = Directories.under(extraRepoTmpDir)
 
   override def afterAll(): Unit = {
     TestInputs.tryRemoveAll(extraRepoTmpDir)
@@ -55,8 +46,8 @@ abstract class BuildTests(server: Boolean) extends TestUtil.ScalaCliBuildSuite {
     )
   )
 
-  def sv2            = Constants.defaultScala213Version
-  val defaultOptions = baseOptions.copy(
+  def sv2: String                  = Constants.defaultScala213Version
+  val defaultOptions: BuildOptions = baseOptions.copy(
     scalaOptions = baseOptions.scalaOptions.copy(
       scalaVersion = Some(MaybeScalaVersion(sv2)),
       scalaBinaryVersion = None
@@ -64,8 +55,8 @@ abstract class BuildTests(server: Boolean) extends TestUtil.ScalaCliBuildSuite {
     scriptOptions = ScriptOptions(Some(true))
   )
 
-  def sv3                  = Constants.defaultScalaVersion
-  val defaultScala3Options = defaultOptions.copy(
+  def sv3: String                        = Constants.defaultScalaVersion
+  val defaultScala3Options: BuildOptions = defaultOptions.copy(
     scalaOptions = defaultOptions.scalaOptions.copy(
       scalaVersion = Some(MaybeScalaVersion(sv3)),
       scalaBinaryVersion = None
@@ -118,7 +109,7 @@ abstract class BuildTests(server: Boolean) extends TestUtil.ScalaCliBuildSuite {
           "simple$package.class",
           "simple$package.tasty"
         )
-        maybeBuild.orThrow.assertNoDiagnostics
+        maybeBuild.orThrow.assertNoDiagnostics()
     }
   }
 
@@ -142,7 +133,7 @@ abstract class BuildTests(server: Boolean) extends TestUtil.ScalaCliBuildSuite {
           "other$package.class",
           "other$package.tasty"
         )
-        maybeBuild.orThrow.assertNoDiagnostics
+        maybeBuild.orThrow.assertNoDiagnostics()
     }
   }
 
@@ -193,7 +184,7 @@ abstract class BuildTests(server: Boolean) extends TestUtil.ScalaCliBuildSuite {
         "simple.class",
         "META-INF/semanticdb/simple.sc.semanticdb"
       )
-      maybeBuild.orThrow.assertNoDiagnostics
+      maybeBuild.orThrow.assertNoDiagnostics()
 
       val outputDir = build.outputOpt.getOrElse(sys.error("no build output???"))
       val semDb     = os.read.bytes(outputDir / "META-INF" / "semanticdb" / "simple.sc.semanticdb")
@@ -247,7 +238,7 @@ abstract class BuildTests(server: Boolean) extends TestUtil.ScalaCliBuildSuite {
         "simple$package.tasty",
         "META-INF/semanticdb/simple.sc.semanticdb"
       )
-      maybeBuild.orThrow.assertNoDiagnostics
+      maybeBuild.orThrow.assertNoDiagnostics()
       val outputDir = build.outputOpt.getOrElse(sys.error("no build output???"))
       val tastyData = TastyData.read(os.read.bytes(outputDir / "simple$_.tasty")).orThrow
       val names     = tastyData.names.simpleNames
@@ -272,7 +263,7 @@ abstract class BuildTests(server: Boolean) extends TestUtil.ScalaCliBuildSuite {
           "simple.class",
           "simple.sjsir"
         )
-        maybeBuild.orThrow.assertNoDiagnostics
+        maybeBuild.orThrow.assertNoDiagnostics()
     }
   }
 
@@ -293,7 +284,7 @@ abstract class BuildTests(server: Boolean) extends TestUtil.ScalaCliBuildSuite {
           "simple.class",
           "simple.nir"
         )
-        maybeBuild.orThrow.assertNoDiagnostics
+        maybeBuild.orThrow.assertNoDiagnostics()
     }
   }
   if (!Properties.isWin)
@@ -316,7 +307,7 @@ abstract class BuildTests(server: Boolean) extends TestUtil.ScalaCliBuildSuite {
         "simple$.class",
         "simple$delayedInit$body.class"
       )
-      maybeBuild.orThrow.assertNoDiagnostics
+      maybeBuild.orThrow.assertNoDiagnostics()
     }
   }
 
@@ -345,7 +336,7 @@ abstract class BuildTests(server: Boolean) extends TestUtil.ScalaCliBuildSuite {
         "simple2$delayedInit$body.class",
         "simple2.class"
       )
-      maybeBuild.orThrow.assertNoDiagnostics
+      maybeBuild.orThrow.assertNoDiagnostics()
     }
   }
 
@@ -656,7 +647,7 @@ abstract class BuildTests(server: Boolean) extends TestUtil.ScalaCliBuildSuite {
     val buildOptions = defaultOptions.copy(
       scalaOptions = defaultOptions.scalaOptions.copy(
         scalacOptions = ShadowingSeq.from(
-          cliScalacOptions.map(ScalacOpt(_)).map(Positioned.commandLine(_))
+          cliScalacOptions.map(ScalacOpt(_)).map(Positioned.commandLine)
         )
       )
     )
@@ -687,7 +678,7 @@ abstract class BuildTests(server: Boolean) extends TestUtil.ScalaCliBuildSuite {
     val buildOptions = defaultOptions.copy(
       javaOptions = defaultOptions.javaOptions.copy(
         javaOpts = ShadowingSeq.from(
-          cliJavaOptions.map(JavaOpt(_)).map(Positioned.commandLine(_))
+          cliJavaOptions.map(JavaOpt(_)).map(Positioned.commandLine)
         )
       )
     )
@@ -966,7 +957,8 @@ abstract class BuildTests(server: Boolean) extends TestUtil.ScalaCliBuildSuite {
              |""".stripMargin
       }
 
-      val testInputs = TestInputs(mainInput +: additionalInputs: _*)
+      val allInputs  = mainInput +: additionalInputs
+      val testInputs = TestInputs(allInputs*)
 
       testInputs.withBuild(options, buildThreads, bloopConfigOpt) { (_, _, maybeBuild) =>
         expect(maybeBuild.exists(_.success))
diff --git a/modules/build/src/test/scala/scala/build/tests/DirectiveTests.scala b/modules/build/src/test/scala/scala/build/tests/DirectiveTests.scala
index 28c4d7bcc5..c9d233f834 100644
--- a/modules/build/src/test/scala/scala/build/tests/DirectiveTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/DirectiveTests.scala
@@ -1,9 +1,15 @@
 package scala.build.tests
 
+import bloop.rifle.BloopRifleConfig
 import com.eed3si9n.expecty.Expecty.expect
 
-import java.io.IOException
-import scala.build.{Build, BuildThreads, Directories, LocalRepo, Position, Positioned}
+import scala.build.Ops.EitherThrowOps
+import scala.build.errors.{
+  CompositeBuildException,
+  DependencyFormatError,
+  FetchingDependenciesError,
+  ToolkitDirectiveMissingVersionError
+}
 import scala.build.options.{
   BuildOptions,
   InternalOptions,
@@ -13,24 +19,13 @@ import scala.build.options.{
   Scope
 }
 import scala.build.tests.util.BloopServer
-import build.Ops.EitherThrowOps
-import dependency.AnyDependency
-
-import scala.build.errors.{
-  CompositeBuildException,
-  DependencyFormatError,
-  FetchingDependenciesError,
-  ToolkitDirectiveMissingVersionError
-}
+import scala.build.{Build, BuildThreads, Directories, LocalRepo, Position, Positioned}
 
 class DirectiveTests extends TestUtil.ScalaCliBuildSuite {
-
-  val buildThreads = BuildThreads.create()
-
-  def bloopConfigOpt = Some(BloopServer.bloopConfig)
-
-  val extraRepoTmpDir = os.temp.dir(prefix = "scala-cli-tests-extra-repo-")
-  val directories     = Directories.under(extraRepoTmpDir)
+  val buildThreads: BuildThreads               = BuildThreads.create()
+  def bloopConfigOpt: Option[BloopRifleConfig] = Some(BloopServer.bloopConfig)
+  val extraRepoTmpDir: os.Path                 = os.temp.dir(prefix = "scala-cli-tests-extra-repo-")
+  val directories: Directories                 = Directories.under(extraRepoTmpDir)
 
   override def afterAll(): Unit = {
     TestInputs.tryRemoveAll(extraRepoTmpDir)
@@ -109,17 +104,17 @@ class DirectiveTests extends TestUtil.ScalaCliBuildSuite {
     )
     testInputs.withBuilds(baseOptions, buildThreads, bloopConfigOpt) {
       (_, _, maybeBuilds) =>
-        val expectedVersion  = "latest.release"
-        val builds           = maybeBuilds.orThrow
-        val Some(mainBuild)  = builds.get(Scope.Main)
-        val Some(toolkitDep) =
-          mainBuild.options.classPathOptions.extraDependencies.toSeq.headOption.map(_.value)
+        val expectedVersion = "latest.release"
+        val builds          = maybeBuilds.orThrow
+        val mainBuild       = builds.get(Scope.Main).get
+        val toolkitDep      =
+          mainBuild.options.classPathOptions.extraDependencies.toSeq.headOption.map(_.value).get
         expect(toolkitDep.organization == Constants.toolkitOrganization)
         expect(toolkitDep.name == Constants.toolkitName)
         expect(toolkitDep.version == expectedVersion)
-        val Some(testBuild)      = builds.get(Scope.Test)
-        val Some(toolkitTestDep) =
-          testBuild.options.classPathOptions.extraDependencies.toSeq.headOption.map(_.value)
+        val testBuild      = builds.get(Scope.Test).get
+        val toolkitTestDep =
+          testBuild.options.classPathOptions.extraDependencies.toSeq.headOption.map(_.value).get
         expect(toolkitTestDep.organization == Constants.toolkitOrganization)
         expect(toolkitTestDep.name == Constants.toolkitTestName)
         expect(toolkitTestDep.version == expectedVersion)
@@ -138,6 +133,7 @@ class DirectiveTests extends TestUtil.ScalaCliBuildSuite {
           maybeBuilds match
             case Left(ToolkitDirectiveMissingVersionError(_, errorKey)) =>
               expect(errorKey == toolkitDirectiveKey)
+            case _ => sys.error("should not happen")
       }
     }
   for (scope <- Scope.all) {
@@ -350,10 +346,10 @@ class DirectiveTests extends TestUtil.ScalaCliBuildSuite {
       os.rel / dummySourcesJar -> "dummy-sources"
     ).withBuild(baseOptions, buildThreads, bloopConfigOpt) {
       (root, _, maybeBuild) =>
-        val build     = maybeBuild.orThrow
-        val Some(jar) = build.options.classPathOptions.extraClassPath.headOption
+        val build = maybeBuild.orThrow
+        val jar   = build.options.classPathOptions.extraClassPath.head
         expect(jar == root / dummyJar)
-        val Some(sourceJar) = build.options.classPathOptions.extraSourceJars.headOption
+        val sourceJar = build.options.classPathOptions.extraSourceJars.head
         expect(sourceJar == root / dummySourcesJar)
     }
   }
@@ -466,7 +462,10 @@ class DirectiveTests extends TestUtil.ScalaCliBuildSuite {
         errors match {
           case error: CompositeBuildException =>
             expect(error.exceptions.length == 2)
-            expect(error.exceptions.forall(_.isInstanceOf[FetchingDependenciesError]))
+            expect(error.exceptions.forall {
+              case _: FetchingDependenciesError => true
+              case _                            => false
+            })
             expect(error.exceptions.forall(_.positions.length == 1))
 
             {
@@ -516,7 +515,7 @@ class DirectiveTests extends TestUtil.ScalaCliBuildSuite {
           |""".stripMargin
     )
     testInputs.withBuild(Scala322Options, buildThreads, bloopConfigOpt, scope = Scope.Test) {
-      (root, _, maybeBuild) => expect(maybeBuild.exists(_.success))
+      (_, _, maybeBuild) => expect(maybeBuild.exists(_.success))
     }
   }
 }
diff --git a/modules/build/src/test/scala/scala/build/tests/DistinctByTests.scala b/modules/build/src/test/scala/scala/build/tests/DistinctByTests.scala
index 38077462de..385aa9fca4 100644
--- a/modules/build/src/test/scala/scala/build/tests/DistinctByTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/DistinctByTests.scala
@@ -1,17 +1,15 @@
 package scala.build.tests
 
 import com.eed3si9n.expecty.Expecty.expect
-
-import scala.build.CollectionOps.distinctBy
 class DistinctByTests extends TestUtil.ScalaCliBuildSuite {
   case class Message(a: String, b: Int)
-  val distinctData = Seq(
+  val distinctData: Seq[Message] = Seq(
     Message(a = "1", b = 4),
     Message(a = "2", b = 3),
     Message(a = "3", b = 2),
     Message(a = "4", b = 1)
   )
-  val repeatingData = Seq(
+  val repeatingData: Seq[Message] = Seq(
     Message(a = "1", b = 4),
     Message(a = "1", b = 44),
     Message(a = "2", b = 3),
diff --git a/modules/build/src/test/scala/scala/build/tests/ExcludeTests.scala b/modules/build/src/test/scala/scala/build/tests/ExcludeTests.scala
index a3c1a0a2ea..87a8db9a30 100644
--- a/modules/build/src/test/scala/scala/build/tests/ExcludeTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/ExcludeTests.scala
@@ -6,17 +6,16 @@ import coursier.cache.{ArchiveCache, ArtifactError, Cache}
 import coursier.util.{Artifact, EitherT, Task}
 
 import java.io.File
+
 import scala.build.Ops.*
-import scala.build.Sources
-import scala.build.CrossSources
 import scala.build.errors.ExcludeDefinitionError
 import scala.build.input.ScalaCliInvokeData
 import scala.build.options.{BuildOptions, Scope, SuppressWarningOptions}
 import scala.build.preprocessing.Preprocessor
+import scala.build.{CrossSources, Sources}
 import scala.concurrent.ExecutionContext
 
 class ExcludeTests extends TestUtil.ScalaCliBuildSuite {
-
   val preprocessors: Seq[Preprocessor] = Sources.defaultPreprocessors(
     archiveCache = ArchiveCache().withCache(
       new Cache[Task] {
diff --git a/modules/build/src/test/scala/scala/build/tests/InputsTests.scala b/modules/build/src/test/scala/scala/build/tests/InputsTests.scala
index a2f7fcc7bf..5cf10bdd3e 100644
--- a/modules/build/src/test/scala/scala/build/tests/InputsTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/InputsTests.scala
@@ -3,7 +3,7 @@ package scala.build.tests
 import bloop.rifle.BloopRifleConfig
 import com.eed3si9n.expecty.Expecty.expect
 
-import scala.build.Build
+import scala.build.input.ElementsUtils.*
 import scala.build.input.{
   Inputs,
   ScalaCliInvokeData,
@@ -11,11 +11,10 @@ import scala.build.input.{
   VirtualScalaFile,
   VirtualScript
 }
-import scala.build.input.ElementsUtils.*
-import scala.build.options.{BuildOptions, InternalOptions, MaybeScalaVersion}
-import scala.build.tests.util.BloopServer
-import scala.build.{BuildThreads, Directories, LocalRepo}
 import scala.build.internal.Constants
+import scala.build.options.{BuildOptions, InternalOptions}
+import scala.build.tests.util.BloopServer
+import scala.build.{Build, BuildThreads, Directories, LocalRepo}
 
 class InputsTests extends TestUtil.ScalaCliBuildSuite {
   val buildThreads: BuildThreads               = BuildThreads.create()
@@ -145,7 +144,7 @@ class InputsTests extends TestUtil.ScalaCliBuildSuite {
       val elements = Inputs.validateArgs(
         urls,
         root,
-        download = url => Right(Array.emptyByteArray),
+        download = _ => Right(Array.emptyByteArray),
         stdinOpt = None,
         acceptFds = true,
         enableMarkdown = true
diff --git a/modules/build/src/test/scala/scala/build/tests/OfflineTests.scala b/modules/build/src/test/scala/scala/build/tests/OfflineTests.scala
index d3b205d9b1..8aafc497bc 100644
--- a/modules/build/src/test/scala/scala/build/tests/OfflineTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/OfflineTests.scala
@@ -1,36 +1,15 @@
 package scala.build.tests
+import coursier.cache.FileCache
 
-import com.eed3si9n.expecty.Expecty.expect
-import coursier.cache.{CacheLogger, FileCache}
-import org.scalajs.logging.{NullLogger, Logger as ScalaJsLogger}
-
-import java.util.concurrent.TimeUnit
-import scala.build.Ops.*
-import scala.build.bsp.{
-  BspServer,
-  ScalaScriptBuildServer,
-  WrappedSourceItem,
-  WrappedSourcesItem,
-  WrappedSourcesParams,
-  WrappedSourcesResult
-}
-import scala.build.errors.{
-  InvalidBinaryScalaVersionError,
-  NoValidScalaVersionFoundError,
-  ScalaVersionError,
-  UnsupportedScalaVersionError
-}
-import scala.build.internal.ClassCodeWrapper
-import scala.build.options.{BuildOptions, InternalOptions, Scope}
+import scala.build.errors.ScalaVersionError
+import scala.build.options.{BuildOptions, InternalOptions}
 import scala.build.tests.Constants
-import scala.build.{Build, BuildThreads, Directories, GeneratedSource, LocalRepo}
-import scala.collection.mutable.ArrayBuffer
-import scala.jdk.CollectionConverters.*
+import scala.build.{BuildThreads, Directories}
 
 class OfflineTests extends TestUtil.ScalaCliBuildSuite {
-  val extraRepoTmpDir = os.temp.dir(prefix = "scala-cli-tests-offline-")
-  val directories     = Directories.under(extraRepoTmpDir)
-  val baseOptions     = BuildOptions(
+  val extraRepoTmpDir: os.Path  = os.temp.dir(prefix = "scala-cli-tests-offline-")
+  val directories: Directories  = Directories.under(extraRepoTmpDir)
+  val baseOptions: BuildOptions = BuildOptions(
     internal = InternalOptions(
       cache = Some(FileCache()
         .withLocation(directories.cacheDir.toString)
@@ -38,7 +17,7 @@ class OfflineTests extends TestUtil.ScalaCliBuildSuite {
     )
   )
 
-  val buildThreads = BuildThreads.create()
+  val buildThreads: BuildThreads = BuildThreads.create()
 
   for (
     defaultVersion <- Seq(
@@ -58,7 +37,7 @@ class OfflineTests extends TestUtil.ScalaCliBuildSuite {
       )
 
       testInputs.withBuild(baseOptions, buildThreads, None) {
-        (root, _, maybeBuild) =>
+        (_, _, maybeBuild) =>
           maybeBuild match {
             case Left(e: ScalaVersionError) =>
               munit.Assertions.fail(
diff --git a/modules/build/src/test/scala/scala/build/tests/PackagingUsingDirectiveTests.scala b/modules/build/src/test/scala/scala/build/tests/PackagingUsingDirectiveTests.scala
index 3072a1791e..9b0656cebf 100644
--- a/modules/build/src/test/scala/scala/build/tests/PackagingUsingDirectiveTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/PackagingUsingDirectiveTests.scala
@@ -1,5 +1,6 @@
 package scala.build.tests
 
+import bloop.rifle.BloopRifleConfig
 import com.eed3si9n.expecty.Expecty.expect
 
 import scala.build.options.{BuildOptions, InternalOptions, PackageType}
@@ -7,12 +8,11 @@ import scala.build.tests.util.BloopServer
 import scala.build.{BuildThreads, Directories, LocalRepo}
 
 class PackagingUsingDirectiveTests extends TestUtil.ScalaCliBuildSuite {
+  val buildThreads: BuildThreads            = BuildThreads.create()
+  def bloopConfig: Option[BloopRifleConfig] = Some(BloopServer.bloopConfig)
 
-  val buildThreads = BuildThreads.create()
-  def bloopConfig  = Some(BloopServer.bloopConfig)
-
-  val extraRepoTmpDir = os.temp.dir(prefix = "scala-cli-tests-extra-repo-")
-  val directories     = Directories.under(extraRepoTmpDir)
+  val extraRepoTmpDir: os.Path = os.temp.dir(prefix = "scala-cli-tests-extra-repo-")
+  val directories: Directories = Directories.under(extraRepoTmpDir)
 
   val buildOptions = BuildOptions(
     internal = InternalOptions(
diff --git a/modules/build/src/test/scala/scala/build/tests/PreprocessingTests.scala b/modules/build/src/test/scala/scala/build/tests/PreprocessingTests.scala
index f3089c964f..bcc4ca5864 100644
--- a/modules/build/src/test/scala/scala/build/tests/PreprocessingTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/PreprocessingTests.scala
@@ -1,13 +1,12 @@
 package scala.build.tests
 
-import scala.build.preprocessing.{MarkdownPreprocessor, ScalaPreprocessor, ScriptPreprocessor}
 import com.eed3si9n.expecty.Expecty.expect
 
-import scala.build.input.{Inputs, MarkdownFile, ScalaCliInvokeData, Script, SourceScalaFile}
+import scala.build.input.{MarkdownFile, ScalaCliInvokeData, Script, SourceScalaFile}
 import scala.build.options.SuppressWarningOptions
+import scala.build.preprocessing.{MarkdownPreprocessor, ScalaPreprocessor, ScriptPreprocessor}
 
 class PreprocessingTests extends TestUtil.ScalaCliBuildSuite {
-
   test("Report error if scala file not exists") {
     val logger    = TestLogger()
     val scalaFile = SourceScalaFile(os.temp.dir(), os.SubPath("NotExists.scala"))
diff --git a/modules/build/src/test/scala/scala/build/tests/ReplArtifactsTests.scala b/modules/build/src/test/scala/scala/build/tests/ReplArtifactsTests.scala
index 806fadea86..ba7bf8407e 100644
--- a/modules/build/src/test/scala/scala/build/tests/ReplArtifactsTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/ReplArtifactsTests.scala
@@ -4,12 +4,11 @@ import com.eed3si9n.expecty.Expecty.expect
 import coursier.cache.FileCache
 import dependency.ScalaParameters
 
-import scala.build.{Directories, Logger, ReplArtifacts}
+import scala.build.{Logger, ReplArtifacts}
 
 class ReplArtifactsTests extends TestUtil.ScalaCliBuildSuite {
-
   def scalaPyTest(version: String, usesFormerOrg: Boolean = false): Unit =
-    TestInputs.withTmpDir("replartifactstests") { root =>
+    TestInputs.withTmpDir("replartifactstests") { _ =>
       val artifacts = ReplArtifacts.ammonite(
         scalaParams = ScalaParameters("2.13.8"),
         ammoniteVersion = "2.5.4",
diff --git a/modules/build/src/test/scala/scala/build/tests/ScalaNativeUsingDirectiveTests.scala b/modules/build/src/test/scala/scala/build/tests/ScalaNativeUsingDirectiveTests.scala
index 3fab0b285f..63eb9289ae 100644
--- a/modules/build/src/test/scala/scala/build/tests/ScalaNativeUsingDirectiveTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/ScalaNativeUsingDirectiveTests.scala
@@ -1,5 +1,6 @@
 package scala.build.tests
 
+import bloop.rifle.BloopRifleConfig
 import com.eed3si9n.expecty.Expecty.expect
 
 import scala.build.errors.UsingDirectiveValueNumError
@@ -8,12 +9,11 @@ import scala.build.tests.util.BloopServer
 import scala.build.{BuildThreads, Directories, LocalRepo}
 
 class ScalaNativeUsingDirectiveTests extends TestUtil.ScalaCliBuildSuite {
+  val buildThreads: BuildThreads            = BuildThreads.create()
+  def bloopConfig: Option[BloopRifleConfig] = Some(BloopServer.bloopConfig)
 
-  val buildThreads = BuildThreads.create()
-  def bloopConfig  = Some(BloopServer.bloopConfig)
-
-  val extraRepoTmpDir = os.temp.dir(prefix = "scala-cli-tests-extra-repo-")
-  val directories     = Directories.under(extraRepoTmpDir)
+  val extraRepoTmpDir: os.Path = os.temp.dir(prefix = "scala-cli-tests-extra-repo-")
+  val directories: Directories = Directories.under(extraRepoTmpDir)
 
   val buildOptions = BuildOptions(
     internal = InternalOptions(
@@ -142,7 +142,7 @@ class ScalaNativeUsingDirectiveTests extends TestUtil.ScalaCliBuildSuite {
 
     inputs.withLoadedBuild(buildOptions, buildThreads, bloopConfig) { (_, _, maybeBuild) =>
       assert(
-        maybeBuild.options.scalaNativeOptions.compileOptions(0) == "compileOption1"
+        maybeBuild.options.scalaNativeOptions.compileOptions.head == "compileOption1"
       )
       assert(
         maybeBuild.options.scalaNativeOptions.compileOptions(1) == "compileOption2"
@@ -215,7 +215,7 @@ class ScalaNativeUsingDirectiveTests extends TestUtil.ScalaCliBuildSuite {
     )
     inputs.withLoadedBuild(buildOptions, buildThreads, bloopConfig) { (_, _, maybeBuild) =>
       assert(
-        maybeBuild.options.scalaNativeOptions.linkingOptions(0) == "linkingOption1"
+        maybeBuild.options.scalaNativeOptions.linkingOptions.head == "linkingOption1"
       )
       assert(
         maybeBuild.options.scalaNativeOptions.linkingOptions(1) == "linkingOption2"
diff --git a/modules/build/src/test/scala/scala/build/tests/ScalaPreprocessorTests.scala b/modules/build/src/test/scala/scala/build/tests/ScalaPreprocessorTests.scala
index ece48de5f0..bceabb8e28 100644
--- a/modules/build/src/test/scala/scala/build/tests/ScalaPreprocessorTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/ScalaPreprocessorTests.scala
@@ -4,7 +4,7 @@ import com.eed3si9n.expecty.Expecty.expect
 
 import scala.build.input.{ScalaCliInvokeData, Script, SourceScalaFile}
 import scala.build.options.SuppressWarningOptions
-import scala.build.preprocessing.{PreprocessedSource, ScalaPreprocessor, ScriptPreprocessor}
+import scala.build.preprocessing.{ScalaPreprocessor, ScriptPreprocessor}
 
 class ScalaPreprocessorTests extends TestUtil.ScalaCliBuildSuite {
 
@@ -21,15 +21,15 @@ class ScalaPreprocessorTests extends TestUtil.ScalaCliBuildSuite {
          |    println(os.pwd)
          |  }
          |}""".stripMargin).fromRoot { root =>
-      val scalaFile           = SourceScalaFile(root, os.sub / "Main.scala")
-      val Some(Right(result)) = ScalaPreprocessor.preprocess(
+      val scalaFile = SourceScalaFile(root, os.sub / "Main.scala")
+      val result    = ScalaPreprocessor.preprocess(
         scalaFile,
         logger = TestLogger(),
         allowRestrictedFeatures = true,
         suppressWarningOptions = SuppressWarningOptions()
-      )(using ScalaCliInvokeData.dummy)
+      )(using ScalaCliInvokeData.dummy).get.getOrElse(sys.error("preprocessing failed"))
       expect(result.nonEmpty)
-      val Some(directivesPositions) = result.head.directivesPositions
+      val directivesPositions = result.head.directivesPositions.get
       expect(directivesPositions.startPos == 0 -> 0)
       expect(directivesPositions.endPos == 3   -> lastUsingLine.length)
     }
@@ -43,21 +43,21 @@ class ScalaPreprocessorTests extends TestUtil.ScalaCliBuildSuite {
          |$depLine
          |println(os.pwd)
          |""".stripMargin).fromRoot { root =>
-      val scalaFile           = Script(root, os.sub / "sample.sc", None)
-      val Some(Right(result)) = ScriptPreprocessor.preprocess(
+      val scalaFile = Script(root, os.sub / "sample.sc", None)
+      val result    = ScriptPreprocessor.preprocess(
         scalaFile,
         logger = TestLogger(),
         allowRestrictedFeatures = false,
         suppressWarningOptions = SuppressWarningOptions()
-      )(using ScalaCliInvokeData.dummy)
+      )(using ScalaCliInvokeData.dummy).get.getOrElse(sys.error("preprocessing failed"))
       expect(result.nonEmpty)
-      val Some(directivesPositions) = result.head.directivesPositions
+      val directivesPositions = result.head.directivesPositions.get
       expect(directivesPositions.startPos == 0 -> 0)
       expect(directivesPositions.endPos == 2   -> depLine.length)
     }
   }
 
-  val lastUsingLines = Seq(
+  val lastUsingLines: Seq[(String, String)] = Seq(
     "//> using dep com.lihaoyi::os-lib::0.8.1 com.lihaoyi::os-lib::0.8.1" -> "string literal",
     "//> using scala 2.13.7"                                              -> "numerical string",
     "//> using objectWrapper true"                                        -> "boolean literal",
@@ -76,15 +76,15 @@ class ScalaPreprocessorTests extends TestUtil.ScalaCliBuildSuite {
            |    println(os.pwd)
            |  }
            |}""".stripMargin).fromRoot { root =>
-        val scalaFile           = SourceScalaFile(root, os.sub / "Main.scala")
-        val Some(Right(result)) = ScalaPreprocessor.preprocess(
+        val scalaFile = SourceScalaFile(root, os.sub / "Main.scala")
+        val result    = ScalaPreprocessor.preprocess(
           scalaFile,
           logger = TestLogger(),
           allowRestrictedFeatures = true,
           suppressWarningOptions = SuppressWarningOptions()
-        )(using ScalaCliInvokeData.dummy)
+        )(using ScalaCliInvokeData.dummy).get.getOrElse(sys.error("preprocessing failed"))
         expect(result.nonEmpty)
-        val Some(directivesPositions) = result.head.directivesPositions
+        val directivesPositions = result.head.directivesPositions.get
         expect(directivesPositions.startPos == 0 -> 0)
         expect(directivesPositions.endPos == 3   -> lastUsingLine.length)
       }
diff --git a/modules/build/src/test/scala/scala/build/tests/ScriptWrapperTests.scala b/modules/build/src/test/scala/scala/build/tests/ScriptWrapperTests.scala
index 13e5ae054c..5076d89532 100644
--- a/modules/build/src/test/scala/scala/build/tests/ScriptWrapperTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/ScriptWrapperTests.scala
@@ -1,18 +1,15 @@
 package scala.build.tests
 
+import bloop.rifle.BloopRifleConfig
 import com.eed3si9n.expecty.Expecty.expect
 
-import java.io.IOException
 import scala.build.Ops.EitherThrowOps
-import scala.build.errors.ToolkitDirectiveMissingVersionError
 import scala.build.options.{
   BuildOptions,
   InternalOptions,
   MaybeScalaVersion,
   Platform,
   ScalaOptions,
-  ScalacOpt,
-  Scope,
   ScriptOptions
 }
 import scala.build.tests.util.BloopServer
@@ -20,7 +17,7 @@ import scala.build.{Build, BuildThreads, Directories, LocalRepo, Position, Posit
 
 class ScriptWrapperTests extends TestUtil.ScalaCliBuildSuite {
 
-  def expectAppWrapper(wrapperName: String, path: os.Path) = {
+  def expectAppWrapper(wrapperName: String, path: os.Path): Unit = {
     val generatedFileContent = os.read(path)
     assert(
       generatedFileContent.contains(s"object $wrapperName extends App {"),
@@ -33,7 +30,7 @@ class ScriptWrapperTests extends TestUtil.ScalaCliBuildSuite {
     )
   }
 
-  def expectObjectWrapper(wrapperName: String, path: os.Path) = {
+  def expectObjectWrapper(wrapperName: String, path: os.Path): Unit = {
     val generatedFileContent = os.read(path)
     assert(
       generatedFileContent.contains(s"object $wrapperName {"),
@@ -46,7 +43,7 @@ class ScriptWrapperTests extends TestUtil.ScalaCliBuildSuite {
     )
   }
 
-  def expectClassWrapper(wrapperName: String, path: os.Path) = {
+  def expectClassWrapper(wrapperName: String, path: os.Path): Unit = {
     val generatedFileContent = os.read(path)
     assert(
       generatedFileContent.contains(s"final class $wrapperName$$_"),
@@ -59,12 +56,11 @@ class ScriptWrapperTests extends TestUtil.ScalaCliBuildSuite {
     )
   }
 
-  val buildThreads = BuildThreads.create()
+  val buildThreads: BuildThreads               = BuildThreads.create()
+  def bloopConfigOpt: Option[BloopRifleConfig] = Some(BloopServer.bloopConfig)
 
-  def bloopConfigOpt = Some(BloopServer.bloopConfig)
-
-  val extraRepoTmpDir = os.temp.dir(prefix = "scala-cli-tests-extra-repo-")
-  val directories     = Directories.under(extraRepoTmpDir)
+  val extraRepoTmpDir: os.Path = os.temp.dir(prefix = "scala-cli-tests-extra-repo-")
+  val directories: Directories = Directories.under(extraRepoTmpDir)
 
   override def afterAll(): Unit = {
     TestInputs.tryRemoveAll(extraRepoTmpDir)
@@ -152,7 +148,7 @@ class ScriptWrapperTests extends TestUtil.ScalaCliBuildSuite {
     test(
       s"object wrapper forced with ${if (useDirectives) directive else optionName}"
     ) {
-      inputs.withBuild(options orElse baseOptions, buildThreads, bloopConfigOpt) {
+      inputs.withBuild(options.orElse(baseOptions), buildThreads, bloopConfigOpt) {
         (root, _, maybeBuild) =>
           expect(maybeBuild.orThrow.success)
           val projectDir = os.list(root / ".scala-build").filter(
@@ -195,7 +191,7 @@ class ScriptWrapperTests extends TestUtil.ScalaCliBuildSuite {
     test(
       s"App object wrapper forced with ${if (useDirectives) directive else optionName}"
     ) {
-      inputs.withBuild(options orElse baseOptions, buildThreads, bloopConfigOpt) {
+      inputs.withBuild(options.orElse(baseOptions), buildThreads, bloopConfigOpt) {
         (root, _, maybeBuild) =>
           expect(maybeBuild.orThrow.success)
           val projectDir = os.list(root / ".scala-build").filter(
diff --git a/modules/build/src/test/scala/scala/build/tests/SourceGeneratorTests.scala b/modules/build/src/test/scala/scala/build/tests/SourceGeneratorTests.scala
index b39e8e07b8..98e57a75b4 100644
--- a/modules/build/src/test/scala/scala/build/tests/SourceGeneratorTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/SourceGeneratorTests.scala
@@ -2,22 +2,11 @@ package scala.build.tests
 
 import com.eed3si9n.expecty.Expecty.expect
 
-import java.io.IOException
 import scala.Console.println
 import scala.build.Ops.EitherThrowOps
-import scala.build.errors.ToolkitDirectiveMissingVersionError
-import scala.build.options.{
-  BuildOptions,
-  InternalOptions,
-  MaybeScalaVersion,
-  Platform,
-  ScalaOptions,
-  ScalacOpt,
-  Scope,
-  ScriptOptions
-}
+import scala.build.options.{BuildOptions, InternalOptions, Scope}
 import scala.build.tests.util.BloopServer
-import scala.build.{Build, BuildThreads, Directories, LocalRepo, Position, Positioned}
+import scala.build.{Build, BuildThreads, Directories, LocalRepo, Position}
 
 class SourceGeneratorTests extends TestUtil.ScalaCliBuildSuite {
 
diff --git a/modules/build/src/test/scala/scala/build/tests/SourcesTests.scala b/modules/build/src/test/scala/scala/build/tests/SourcesTests.scala
index 56b114d8cd..5968ac4014 100644
--- a/modules/build/src/test/scala/scala/build/tests/SourcesTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/SourcesTests.scala
@@ -1,32 +1,37 @@
 package scala.build.tests
 
 import com.eed3si9n.expecty.Expecty.expect
-import coursier.cache.{ArchiveCache, Cache}
-import coursier.util.{Artifact, Task}
+import coursier.cache.Cache.Fetch
+import coursier.cache.{ArchiveCache, ArtifactError, Cache}
+import coursier.util.{Artifact, EitherT, Task}
 import dependency.*
 
+import java.io.File
 import java.nio.charset.StandardCharsets
+
 import scala.build.Ops.*
-import scala.build.{CrossSources, Position, Sources}
 import scala.build.errors.{UsingDirectiveValueNumError, UsingDirectiveWrongValueTypeError}
 import scala.build.input.ScalaCliInvokeData
-import scala.build.options.{BuildOptions, Scope, SuppressWarningOptions}
 import scala.build.internal.ScalaJsLinkerConfig
+import scala.build.options.{BuildOptions, Scope, SuppressWarningOptions}
+import scala.build.preprocessing.Preprocessor
+import scala.build.{CrossSources, Position, Sources}
+import scala.concurrent.ExecutionContext
 
 class SourcesTests extends TestUtil.ScalaCliBuildSuite {
-
-  def scalaVersion       = "2.13.5"
-  def scalaParams        = ScalaParameters(scalaVersion)
-  def scalaBinaryVersion = scalaParams.scalaBinaryVersion
+  def scalaVersion: String         = "2.13.5"
+  def scalaParams: ScalaParameters = ScalaParameters(scalaVersion)
+  def scalaBinaryVersion: String   = scalaParams.scalaBinaryVersion
 
   given ScalaCliInvokeData = ScalaCliInvokeData.dummy
 
-  val preprocessors = Sources.defaultPreprocessors(
+  val preprocessors: Seq[Preprocessor] = Sources.defaultPreprocessors(
     ArchiveCache().withCache(
       new Cache[Task] {
-        def fetch                    = _ => sys.error("shouldn't be used")
-        def file(artifact: Artifact) = sys.error("shouldn't be used")
-        def ec                       = sys.error("shouldn't be used")
+        def fetch: Fetch[Task] = _ => sys.error("shouldn't be used")
+        def file(artifact: Artifact): EitherT[Task, ArtifactError, File] =
+          sys.error("shouldn't be used")
+        def ec: ExecutionContext = sys.error("shouldn't be used")
       }
     ),
     None,
@@ -73,7 +78,7 @@ class SourcesTests extends TestUtil.ScalaCliBuildSuite {
           )
             .orThrow
 
-        val obtainedDeps = sources.buildOptions.classPathOptions.extraDependencies.toSeq.toSeq.map(
+        val obtainedDeps = sources.buildOptions.classPathOptions.extraDependencies.toSeq.map(
           _.value
         )
 
@@ -121,7 +126,7 @@ class SourcesTests extends TestUtil.ScalaCliBuildSuite {
         sources.buildOptions.classPathOptions.extraDependencies.toSeq.map(_.value) == expectedDeps
       )
       expect(sources.paths.isEmpty)
-      expect(sources.inMemory.length == 0)
+      expect(sources.inMemory.isEmpty)
     }
   }
 
@@ -154,7 +159,7 @@ class SourcesTests extends TestUtil.ScalaCliBuildSuite {
 
       expect(sources.paths.length == 1)
       expect(sources.inMemory.length == 1)
-      expect(sources.inMemory(0).generatedRelPath.last == "AmmDummy.scala")
+      expect(sources.inMemory.head.generatedRelPath.last == "AmmDummy.scala")
     }
   }
 
@@ -194,7 +199,7 @@ class SourcesTests extends TestUtil.ScalaCliBuildSuite {
         sources.buildOptions.classPathOptions.extraDependencies.toSeq.map(_.value) == expectedDeps
       )
       expect(sources.paths.isEmpty)
-      expect(sources.inMemory.length == 0)
+      expect(sources.inMemory.isEmpty)
     }
   }
 
@@ -604,22 +609,22 @@ class SourcesTests extends TestUtil.ScalaCliBuildSuite {
       val jsOptions = sources.buildOptions.scalaJsOptions
       val jsConfig  = jsOptions.linkerConfig(TestLogger())
       expect(
-        jsOptions.version == Some("1.8.0"),
+        jsOptions.version.contains("1.8.0"),
         jsOptions.mode.nameOpt.contains("mode"),
-        jsOptions.moduleKindStr == Some("commonjs"),
-        jsOptions.checkIr == Some(true),
-        jsOptions.emitSourceMaps == true,
-        jsOptions.dom == Some(true),
-        jsOptions.noOpt == Some(true)
+        jsOptions.moduleKindStr.contains("commonjs"),
+        jsOptions.checkIr.contains(true),
+        jsOptions.emitSourceMaps,
+        jsOptions.dom.contains(true),
+        jsOptions.noOpt.contains(true)
       )
       expect(
         jsConfig.moduleKind == ScalaJsLinkerConfig.ModuleKind.CommonJSModule,
-        jsConfig.checkIR == true,
-        jsConfig.sourceMap == true,
-        jsConfig.jsHeader == Some("#!/usr/bin/env node\n"),
-        jsConfig.esFeatures.allowBigIntsForLongs == true,
-        jsConfig.esFeatures.avoidClasses == false,
-        jsConfig.esFeatures.avoidLetsAndConsts == false,
+        jsConfig.checkIR,
+        jsConfig.sourceMap,
+        jsConfig.jsHeader.contains("#!/usr/bin/env node\n"),
+        jsConfig.esFeatures.allowBigIntsForLongs,
+        !jsConfig.esFeatures.avoidClasses,
+        !jsConfig.esFeatures.avoidLetsAndConsts,
         jsConfig.esFeatures.esVersion == "ES2017",
         jsConfig.moduleSplitStyle == ScalaJsLinkerConfig.ModuleSplitStyle.SmallestModules
       )
@@ -699,8 +704,9 @@ class SourcesTests extends TestUtil.ScalaCliBuildSuite {
           SuppressWarningOptions()
         )
       assert(crossSourcesResult.isRight)
-      val Right(CrossSources(onDiskSources, _, _, _, _, _)) =
+      val CrossSources(onDiskSources, _, _, _, _, _) =
         crossSourcesResult.map(_._1)
+          .getOrElse(sys.error("should not happen"))
       val onDiskPaths = onDiskSources.map(_.value._1.last)
       expect(onDiskPaths == inputArgs)
     }
diff --git a/modules/build/src/test/scala/scala/build/tests/TestInputs.scala b/modules/build/src/test/scala/scala/build/tests/TestInputs.scala
index fa75db19d5..d6b34a6df2 100644
--- a/modules/build/src/test/scala/scala/build/tests/TestInputs.scala
+++ b/modules/build/src/test/scala/scala/build/tests/TestInputs.scala
@@ -3,14 +3,14 @@ package scala.build.tests
 import bloop.rifle.BloopRifleConfig
 
 import java.nio.charset.StandardCharsets
-import scala.build.{Build, BuildThreads, Builds, Directories}
+
 import scala.build.compiler.{BloopCompilerMaker, SimpleScalaCompilerMaker}
 import scala.build.errors.BuildException
-import scala.build.input.{Inputs, ScalaCliInvokeData, SubCommand}
-import scala.build.internal.Util
+import scala.build.input.{Inputs, ScalaCliInvokeData}
 import scala.build.options.{BuildOptions, Scope}
-import scala.util.control.NonFatal
+import scala.build.{Build, BuildThreads, Builds}
 import scala.util.Try
+import scala.util.control.NonFatal
 
 final case class TestInputs(
   files: Seq[(os.RelPath, String)],
@@ -79,7 +79,7 @@ final case class TestInputs(
     buildThreads: BuildThreads, // actually only used when bloopConfigOpt is non-empty
     bloopConfigOpt: Option[BloopRifleConfig],
     fromDirectory: Boolean = false
-  )(f: (os.Path, Inputs, Builds) => T) =
+  )(f: (os.Path, Inputs, Builds) => T): T =
     withBuilds(options, buildThreads, bloopConfigOpt, fromDirectory)((p, i, builds) =>
       builds match {
         case Left(e)  => throw e
@@ -174,7 +174,7 @@ object TestInputs {
         Runtime.getRuntime.addShutdownHook(
           new Thread("remove-dir-windows") {
             setDaemon(true)
-            override def run() =
+            override def run(): Unit =
               try os.remove.all(f)
               catch {
                 case NonFatal(e) =>
diff --git a/modules/build/src/test/scala/scala/build/tests/TestLogger.scala b/modules/build/src/test/scala/scala/build/tests/TestLogger.scala
index 52d2a5cce4..35de6eed7e 100644
--- a/modules/build/src/test/scala/scala/build/tests/TestLogger.scala
+++ b/modules/build/src/test/scala/scala/build/tests/TestLogger.scala
@@ -3,16 +3,16 @@ package scala.build.tests
 import bloop.rifle.BloopRifleLogger
 import coursier.cache.CacheLogger
 import coursier.cache.loggers.{FallbackRefreshDisplay, RefreshLogger}
-import org.scalajs.logging.{NullLogger, Logger as ScalaJsLogger}
+import org.scalajs.logging.{Logger as ScalaJsLogger, NullLogger}
+
+import java.io.PrintStream
 
-import scala.build.errors.BuildException
 import scala.build.Logger
-import scala.scalanative.build as sn
-import scala.build.errors.Diagnostic
+import scala.build.errors.{BuildException, Diagnostic}
 import scala.build.internals.FeatureType
+import scala.scalanative.build as sn
 
 case class TestLogger(info: Boolean = true, debug: Boolean = false) extends Logger {
-
   override def log(diagnostics: Seq[Diagnostic]): Unit = {
     diagnostics.foreach { d =>
       System.err.println(d.positions.map(_.render()).mkString("/") ++ ": " ++ d.message)
@@ -76,16 +76,12 @@ case class TestLogger(info: Boolean = true, debug: Boolean = false) extends Logg
     sn.Logger.nullLogger
   def scalaNativeCliInternalLoggerOptions: List[String] =
     List()
-  def bloopBspStderr        = None
-  def bloopBspStdout        = None
-  def bloopCliInheritStdout = false
-  def bloopCliInheritStderr = false
 
-  def compilerOutputStream = System.err
+  def compilerOutputStream: PrintStream = System.err
 
-  def verbosity =
-    if (debug) 2
-    else if (info) 0
+  def verbosity: Int =
+    if debug then 2
+    else if info then 0
     else -1
 
   override def experimentalWarning(featureName: String, featureType: FeatureType): Unit =
diff --git a/modules/build/src/test/scala/scala/build/tests/TestUtil.scala b/modules/build/src/test/scala/scala/build/tests/TestUtil.scala
index 44ad514328..130c80f643 100644
--- a/modules/build/src/test/scala/scala/build/tests/TestUtil.scala
+++ b/modules/build/src/test/scala/scala/build/tests/TestUtil.scala
@@ -1,14 +1,15 @@
 package scala.build.tests
 
-import scala.build.{Build, Positioned}
-import scala.build.options.{BuildOptions, Platform}
+import munit.AnyFixture
 import munit.Assertions.assertEquals
 
 import java.util.concurrent.TimeUnit
+
+import scala.build.options.{BuildOptions, Platform}
+import scala.build.{Build, Positioned}
 import scala.concurrent.duration.FiniteDuration
 
 object TestUtil {
-
   abstract class ScalaCliBuildSuite extends munit.FunSuite {
     extension (munitContext: BeforeEach | AfterEach) {
       def locationAbsolutePath: os.Path =
@@ -19,8 +20,8 @@ object TestUtil {
           }).location.path
         }
     }
-    override def munitTimeout = new FiniteDuration(120, TimeUnit.SECONDS)
-    val testStartEndLogger    = new Fixture[Unit]("files") {
+    override def munitTimeout             = new FiniteDuration(120, TimeUnit.SECONDS)
+    val testStartEndLogger: Fixture[Unit] = new Fixture[Unit]("files") {
       def apply(): Unit = ()
 
       override def beforeEach(context: BeforeEach): Unit = {
@@ -37,10 +38,10 @@ object TestUtil {
         )
       }
     }
-    override def munitFixtures = List(testStartEndLogger)
+    override def munitFixtures: Seq[AnyFixture[?]] = List(testStartEndLogger)
   }
 
-  val isCI = System.getenv("CI") != null
+  val isCI: Boolean = System.getenv("CI") != null
 
   implicit class TestBuildOps(private val build: Build) extends AnyVal {
     private def successfulBuild: Build.Successful =
@@ -62,18 +63,18 @@ object TestUtil {
       )
     }
 
-    def assertNoDiagnostics = assertEquals(build.diagnostics.toSeq.flatten, Nil)
+    def assertNoDiagnostics(): Unit = assertEquals(build.diagnostics.toSeq.flatten, Nil)
 
   }
 
   implicit class TestBuildOptionsOps(private val options: BuildOptions) extends AnyVal {
-    def enableJs =
+    def enableJs: BuildOptions =
       options.copy(
         scalaOptions = options.scalaOptions.copy(
           platform = Some(Positioned.none(Platform.JS))
         )
       )
-    def enableNative =
+    def enableNative: BuildOptions =
       options.copy(
         scalaOptions = options.scalaOptions.copy(
           platform = Some(Positioned.none(Platform.Native))
@@ -98,5 +99,5 @@ object TestUtil {
     case s    => s"$s"
   }
 
-  lazy val cs = Constants.cs
+  lazy val cs: String = Constants.cs
 }
diff --git a/modules/build/src/test/scala/scala/build/tests/markdown/MarkdownCodeBlockTests.scala b/modules/build/src/test/scala/scala/build/tests/markdown/MarkdownCodeBlockTests.scala
index ef8bbe41fa..8f6b9003d6 100644
--- a/modules/build/src/test/scala/scala/build/tests/markdown/MarkdownCodeBlockTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/markdown/MarkdownCodeBlockTests.scala
@@ -5,7 +5,6 @@ import com.eed3si9n.expecty.Expecty.expect
 import scala.build.Position
 import scala.build.errors.{BuildException, MarkdownUnclosedBackticksError}
 import scala.build.internal.markdown.MarkdownCodeBlock
-import scala.build.preprocessing.MarkdownCodeBlockProcessor
 import scala.build.tests.TestUtil
 import scala.build.tests.markdown.MarkdownTestUtil.*
 
@@ -43,8 +42,11 @@ class MarkdownCodeBlockTests extends TestUtil.ScalaCliBuildSuite {
         startLine = 3,
         endLine = 3
       )
-    val path                     = os.sub / "Example.md"
-    val Right(Seq(actualResult)) = MarkdownCodeBlock.findCodeBlocks(path, markdown)
+    val path         = os.sub / "Example.md"
+    val actualResult =
+      MarkdownCodeBlock.findCodeBlocks(path, markdown)
+        .getOrElse(sys.error("failed while finding code blocks"))
+        .head
     expect(actualResult == expectedResult)
   }
 
@@ -65,9 +67,11 @@ class MarkdownCodeBlockTests extends TestUtil.ScalaCliBuildSuite {
         startLine = 3,
         endLine = 4
       )
-    val path                                        = os.sub / "Example.md"
-    val Right(Seq(actualResult: MarkdownCodeBlock)) =
+    val path                            = os.sub / "Example.md"
+    val actualResult: MarkdownCodeBlock =
       MarkdownCodeBlock.findCodeBlocks(path, markdown)
+        .getOrElse(sys.error("failed while finding code blocks"))
+        .head
     showDiffs(actualResult, expectedResult)
     expect(actualResult == expectedResult)
   }
@@ -89,9 +93,11 @@ class MarkdownCodeBlockTests extends TestUtil.ScalaCliBuildSuite {
         startLine = 3,
         endLine = 4
       )
-    val path                                        = os.sub / "Example.md"
-    val Right(Seq(actualResult: MarkdownCodeBlock)) =
+    val path                            = os.sub / "Example.md"
+    val actualResult: MarkdownCodeBlock =
       MarkdownCodeBlock.findCodeBlocks(path, markdown)
+        .getOrElse(sys.error("failed while finding code blocks"))
+        .head
     showDiffs(actualResult, expectedResult)
     expect(actualResult == expectedResult)
   }
@@ -114,8 +120,11 @@ class MarkdownCodeBlockTests extends TestUtil.ScalaCliBuildSuite {
         startLine = 3,
         endLine = 5
       )
-    val path                     = os.sub / "Example.md"
-    val Right(Seq(actualResult)) = MarkdownCodeBlock.findCodeBlocks(path, markdown)
+    val path         = os.sub / "Example.md"
+    val actualResult =
+      MarkdownCodeBlock.findCodeBlocks(path, markdown)
+        .getOrElse(sys.error("failed while finding code blocks"))
+        .head
     expect(actualResult == expectedResult)
   }
 
@@ -139,9 +148,11 @@ class MarkdownCodeBlockTests extends TestUtil.ScalaCliBuildSuite {
         startLine = 3,
         endLine = 6
       )
-    val path                                        = os.sub / "Example.md"
-    val Right(Seq(actualResult: MarkdownCodeBlock)) =
+    val path                            = os.sub / "Example.md"
+    val actualResult: MarkdownCodeBlock =
       MarkdownCodeBlock.findCodeBlocks(path, markdown)
+        .getOrElse(sys.error("failed while finding code blocks"))
+        .head
     showDiffs(actualResult, expectedResult)
     expect(actualResult == expectedResult)
   }
@@ -166,8 +177,11 @@ class MarkdownCodeBlockTests extends TestUtil.ScalaCliBuildSuite {
         startLine = 3,
         endLine = 6
       )
-    val path                     = os.sub / "Example.md"
-    val Right(Seq(actualResult)) = MarkdownCodeBlock.findCodeBlocks(path, markdown)
+    val path         = os.sub / "Example.md"
+    val actualResult =
+      MarkdownCodeBlock.findCodeBlocks(path, markdown)
+        .getOrElse(sys.error("failed while finding code blocks"))
+        .head
     expect(actualResult == expectedResult)
   }
 
@@ -196,9 +210,11 @@ class MarkdownCodeBlockTests extends TestUtil.ScalaCliBuildSuite {
     val path             = os.pwd / subPath
     val expectedPosition = Position.File(Right(path), 2 -> 0, 2 -> 3)
     val expectedError    = MarkdownUnclosedBackticksError("```", Seq(expectedPosition))
-    val Left(result)     = MarkdownCodeBlock.findCodeBlocks(subPath, markdown)
-    expect(result.message == expectedError.message)
-    expect(result.positions == expectedError.positions)
+    val actualException  =
+      MarkdownCodeBlock.findCodeBlocks(subPath, markdown)
+        .left.getOrElse(sys.error("failed while finding code blocks"))
+    expect(actualException.message == expectedError.message)
+    expect(actualException.positions == expectedError.positions)
   }
 
   test("recovery from an unclosed code block error works correctly") {
@@ -224,8 +240,10 @@ class MarkdownCodeBlockTests extends TestUtil.ScalaCliBuildSuite {
       maybeError = Some(be)
       None
     }
-    val Right(Seq(actualResult)) =
+    val actualResult =
       MarkdownCodeBlock.findCodeBlocks(subPath, markdown, maybeRecoverOnError = recoveryFunction)
+        .getOrElse(sys.error("failed while finding code blocks"))
+        .head
     val expectedResult =
       MarkdownCodeBlock(
         info = PlainScalaInfo,
@@ -234,10 +252,10 @@ class MarkdownCodeBlockTests extends TestUtil.ScalaCliBuildSuite {
         endLine = 2
       )
     expect(actualResult == expectedResult)
-    val path              = os.pwd / subPath
-    val expectedPosition  = Position.File(Right(path), 7 -> 0, 7 -> 4)
-    val expectedError     = MarkdownUnclosedBackticksError("````", Seq(expectedPosition))
-    val Some(actualError) = maybeError
+    val path             = os.pwd / subPath
+    val expectedPosition = Position.File(Right(path), 7 -> 0, 7 -> 4)
+    val expectedError    = MarkdownUnclosedBackticksError("````", Seq(expectedPosition))
+    val actualError      = maybeError.get
     expect(actualError.positions == expectedError.positions)
     expect(actualError.message == expectedError.message)
   }
diff --git a/modules/build/src/test/scala/scala/build/tests/markdown/MarkdownCodeWrapperTests.scala b/modules/build/src/test/scala/scala/build/tests/markdown/MarkdownCodeWrapperTests.scala
index e178266bb1..89477fb530 100644
--- a/modules/build/src/test/scala/scala/build/tests/markdown/MarkdownCodeWrapperTests.scala
+++ b/modules/build/src/test/scala/scala/build/tests/markdown/MarkdownCodeWrapperTests.scala
@@ -1,19 +1,13 @@
 package scala.build.tests.markdown
 
-import scala.build.internal.markdown.{MarkdownCodeBlock, MarkdownCodeWrapper}
 import com.eed3si9n.expecty.Expecty.expect
 
-import scala.build.Position
-import scala.build.errors.{BuildException, MarkdownUnclosedBackticksError}
 import scala.build.internal.AmmUtil
-import scala.build.preprocessing.directives.StrictDirective
-import scala.build.preprocessing.{
-  ExtractedDirectives,
-  PreprocessedMarkdown,
-  PreprocessedMarkdownCodeBlocks
-}
+import scala.build.internal.markdown.{MarkdownCodeBlock, MarkdownCodeWrapper}
+import scala.build.preprocessing.{PreprocessedMarkdown, PreprocessedMarkdownCodeBlocks}
 import scala.build.tests.TestUtil
 import scala.build.tests.markdown.MarkdownTestUtil.*
+import scala.language.reflectiveCalls
 
 class MarkdownCodeWrapperTests extends TestUtil.ScalaCliBuildSuite {
 
@@ -206,17 +200,13 @@ class MarkdownCodeWrapperTests extends TestUtil.ScalaCliBuildSuite {
 
   def showDiffs(result: CodeWrapper, expect: String): Unit = {
     val actual: String = result match {
-      case (Some(s), None, None) =>
-        s.code
-      case (None, Some(s), None) =>
-        s.code
-      case (None, None, Some(s)) =>
-        s.code
-      case _ =>
-        result.toString
+      case (Some(s), None, None) => s.code
+      case (None, Some(s), None) => s.code
+      case (None, None, Some(s)) => s.code
+      case _                     => result.toString
 
     }
-    if actual.toString != expect.toString then
+    if actual != expect then
       for (((a, b), i) <- (actual zip expect).zipWithIndex)
         if (a != b) {
           val aa = TestUtil.c2s(a)
diff --git a/modules/build/src/test/scala/scala/build/tests/markdown/MarkdownTestUtil.scala b/modules/build/src/test/scala/scala/build/tests/markdown/MarkdownTestUtil.scala
index 83f1ec991b..cb93232090 100644
--- a/modules/build/src/test/scala/scala/build/tests/markdown/MarkdownTestUtil.scala
+++ b/modules/build/src/test/scala/scala/build/tests/markdown/MarkdownTestUtil.scala
@@ -1,8 +1,8 @@
 package scala.build.tests.markdown
 
 object MarkdownTestUtil {
-  val PlainScalaInfo = Seq("scala")
-  val RawScalaInfo   = Seq("scala", "raw")
-  val TestScalaInfo  = Seq("scala", "test")
-  val ResetScalaInfo = Seq("scala", "reset")
+  val PlainScalaInfo: Seq[String] = Seq("scala")
+  val RawScalaInfo: Seq[String]   = Seq("scala", "raw")
+  val TestScalaInfo: Seq[String]  = Seq("scala", "test")
+  val ResetScalaInfo: Seq[String] = Seq("scala", "reset")
 }
diff --git a/modules/cli/src/test/scala/cli/commands/tests/ReplOptionsTests.scala b/modules/cli/src/test/scala/cli/commands/tests/ReplOptionsTests.scala
index 58fd1f6971..db4e4d17ba 100644
--- a/modules/cli/src/test/scala/cli/commands/tests/ReplOptionsTests.scala
+++ b/modules/cli/src/test/scala/cli/commands/tests/ReplOptionsTests.scala
@@ -7,7 +7,6 @@ import scala.cli.commands.repl.{Repl, ReplOptions, SharedReplOptions}
 import scala.cli.commands.shared.{SharedOptions, SharedPythonOptions}
 
 class ReplOptionsTests extends munit.FunSuite {
-
   test("ScalaPy version") {
     val ver         = "X.Y.Z"
     val replOptions = ReplOptions(
@@ -32,5 +31,4 @@ class ReplOptionsTests extends munit.FunSuite {
     val buildOptions  = Repl.buildOptions0(replOptions, maxVersion, maxLtsVersion)
     expect(buildOptions.scalaOptions.scalaVersion.flatMap(_.versionOpt).contains(maxVersion))
   }
-
 }
diff --git a/modules/cli/src/test/scala/cli/commands/tests/RunOptionsTests.scala b/modules/cli/src/test/scala/cli/commands/tests/RunOptionsTests.scala
index dbcaa92e07..6aaa38a03b 100644
--- a/modules/cli/src/test/scala/cli/commands/tests/RunOptionsTests.scala
+++ b/modules/cli/src/test/scala/cli/commands/tests/RunOptionsTests.scala
@@ -6,7 +6,6 @@ import scala.cli.commands.run.{Run, RunOptions}
 import scala.cli.commands.shared.{SharedOptions, SharedPythonOptions}
 
 class RunOptionsTests extends munit.FunSuite {
-
   test("ScalaPy version") {
     val ver        = "X.Y.Z"
     val runOptions = RunOptions(
@@ -51,5 +50,4 @@ class RunOptionsTests extends munit.FunSuite {
     expect(toolkitDep.name == "toolkit")
     expect(toolkitDep.version == "latest.release")
   }
-
 }
diff --git a/modules/cli/src/test/scala/cli/tests/ArgSplitterTest.scala b/modules/cli/src/test/scala/cli/tests/ArgSplitterTest.scala
index 0160d8800b..5085ef08c2 100644
--- a/modules/cli/src/test/scala/cli/tests/ArgSplitterTest.scala
+++ b/modules/cli/src/test/scala/cli/tests/ArgSplitterTest.scala
@@ -12,5 +12,4 @@ class ArgSplitterTest extends TestUtil.ScalaCliSuite {
     val input = args.map(_.mkString("   ", " ", "")).mkString(" ", "\n", "")
     assertEquals(ArgSplitter.splitToArgs(input), args.flatten)
   }
-
 }
diff --git a/modules/cli/src/test/scala/cli/tests/LauncherCliTest.scala b/modules/cli/src/test/scala/cli/tests/LauncherCliTest.scala
index 73345b862f..abb0d41435 100644
--- a/modules/cli/src/test/scala/cli/tests/LauncherCliTest.scala
+++ b/modules/cli/src/test/scala/cli/tests/LauncherCliTest.scala
@@ -8,7 +8,6 @@ import scala.cli.commands.shared.CoursierOptions
 import scala.cli.launcher.LauncherCli
 
 class LauncherCliTest extends TestUtil.ScalaCliSuite {
-
   test("resolve nightly version".flaky) {
     val logger          = TestLogger()
     val cache           = CoursierOptions().coursierCache(logger.coursierLogger(""))
@@ -19,7 +18,7 @@ class LauncherCliTest extends TestUtil.ScalaCliSuite {
     expect(nightlyCliVersion.endsWith("-SNAPSHOT"))
   }
 
-  val expectedScalaCliVersions = Seq(
+  val expectedScalaCliVersions: Seq[(String, String)] = Seq(
     "0.1.2"                       -> Constants.defaultScala212Version,
     "0.1.1+43-g15666b67-SNAPSHOT" -> Constants.defaultScala212Version,
     "0.1.3"                       -> Constants.defaultScala213Version,
@@ -29,8 +28,6 @@ class LauncherCliTest extends TestUtil.ScalaCliSuite {
   for ((cliVersion, expectedScalaVersion) <- expectedScalaCliVersions)
     test(s"use expected scala version for Scala CLI launcher: $cliVersion") {
       val scalaVersion = LauncherCli.scalaCliScalaVersion(cliVersion)
-
       expect(scalaVersion == expectedScalaVersion)
     }
-
 }
diff --git a/modules/cli/src/test/scala/cli/tests/OptionsCheck.scala b/modules/cli/src/test/scala/cli/tests/OptionsCheck.scala
index 4306a88e95..9510c1a6b5 100644
--- a/modules/cli/src/test/scala/cli/tests/OptionsCheck.scala
+++ b/modules/cli/src/test/scala/cli/tests/OptionsCheck.scala
@@ -6,10 +6,7 @@ import scala.cli.ScalaCliCommands
 import scala.cli.commands.shared.HasGlobalOptions
 
 class OptionsCheck extends TestUtil.ScalaCliSuite {
-  for (
-    command <-
-      new ScalaCliCommands("scala-cli", "scala-cli", "Scala CLI").commands
-  )
+  for (command <- new ScalaCliCommands("scala-cli", "scala-cli", "Scala CLI").commands)
     test(s"No duplicated options in ${command.names.head.mkString(" ")}") {
       command.ensureNoDuplicates()
     }
diff --git a/modules/cli/src/test/scala/cli/tests/PackageTests.scala b/modules/cli/src/test/scala/cli/tests/PackageTests.scala
index 013dd23c8a..50f61ca4f5 100644
--- a/modules/cli/src/test/scala/cli/tests/PackageTests.scala
+++ b/modules/cli/src/test/scala/cli/tests/PackageTests.scala
@@ -1,5 +1,6 @@
 package cli.tests
 
+import bloop.rifle.BloopRifleConfig
 import com.eed3si9n.expecty.Expecty.expect
 
 import java.nio.file.FileSystems
@@ -13,11 +14,11 @@ import scala.cli.commands.package0.Package
 import scala.cli.packaging.Library
 
 class PackageTests extends TestUtil.ScalaCliSuite {
-  val buildThreads = BuildThreads.create()
-  def bloopConfig  = BloopServer.bloopConfig
+  val buildThreads: BuildThreads    = BuildThreads.create()
+  def bloopConfig: BloopRifleConfig = BloopServer.bloopConfig
 
-  val extraRepoTmpDir = os.temp.dir(prefix = "scala-cli-tests-extra-repo-")
-  val directories     = Directories.under(extraRepoTmpDir)
+  val extraRepoTmpDir: os.Path = os.temp.dir(prefix = "scala-cli-tests-extra-repo-")
+  val directories: Directories = Directories.under(extraRepoTmpDir)
 
   val defaultOptions = BuildOptions(
     internal = InternalOptions(
@@ -92,5 +93,4 @@ class PackageTests extends TestUtil.ScalaCliSuite {
         expect(packageType == PackageType.Native.Application)
     }
   }
-
 }
diff --git a/modules/cli/src/test/scala/cli/tests/TestUtil.scala b/modules/cli/src/test/scala/cli/tests/TestUtil.scala
index 711653e8a4..0fbf8a8b91 100644
--- a/modules/cli/src/test/scala/cli/tests/TestUtil.scala
+++ b/modules/cli/src/test/scala/cli/tests/TestUtil.scala
@@ -2,6 +2,7 @@ package cli.tests
 
 import coursier.cache.{ArtifactError, FileCache}
 import coursier.util.{Artifact, Task}
+import munit.AnyFixture
 
 import java.io.File
 import java.util.concurrent.TimeUnit
@@ -23,7 +24,7 @@ object TestUtil {
 
     override def munitTimeout = new FiniteDuration(120, TimeUnit.SECONDS)
 
-    val testStartEndLogger = new Fixture[Unit]("files") {
+    val testStartEndLogger: Fixture[Unit] = new Fixture[Unit]("files") {
       def apply(): Unit = ()
 
       override def beforeEach(context: BeforeEach): Unit = {
@@ -41,7 +42,7 @@ object TestUtil {
       }
     }
 
-    override def munitFixtures = List(testStartEndLogger)
+    override def munitFixtures: Seq[AnyFixture[?]] = List(testStartEndLogger)
   }
 
   def downloadFile(url: String): Either[ArtifactError, Array[Byte]] = {
diff --git a/modules/options/src/test/scala/scala/build/options/ConfigMonoidTest.scala b/modules/options/src/test/scala/scala/build/options/ConfigMonoidTest.scala
index e32581f772..25ddd17a8e 100644
--- a/modules/options/src/test/scala/scala/build/options/ConfigMonoidTest.scala
+++ b/modules/options/src/test/scala/scala/build/options/ConfigMonoidTest.scala
@@ -7,7 +7,6 @@ case class Inner(
 )
 
 object Inner {
-  import ConfigMonoid.*
   implicit def monoid: ConfigMonoid[Inner] = ConfigMonoid.derive
 }
 
@@ -52,6 +51,5 @@ class ConfigMonoidTest extends munit.FunSuite {
 
     assertEquals(Outer.monoid.orElse(outer1, outer2).name, Some("o1"))
     assertEquals(Outer.monoid.orElse(outer2, outer1).name, Some("o2"))
-
   }
 }