Add extraTestDigests key

main/src/main/scala/sbt/Defaults.scala

@@ -1310,7 +1310,8 @@ object Defaults extends BuildCommon {
         testListeners :== Nil,
         testOptions :== Nil,
         testResultLogger :== TestResultLogger.Default,
-        testOnly / testFilter :== (IncrementalTest.selectedFilter _)
+        testOnly / testFilter :== (IncrementalTest.selectedFilter _),
+        extraTestDigests :== Nil,
       )
     )
   lazy val testTasks: Seq[Setting[_]] =
@@ -1333,6 +1334,7 @@ object Defaults extends BuildCommon {
         .triggeredBy(compile)
         .value,
       testQuick / testFilter := IncrementalTest.filterTask.value,
+      extraTestDigests ++= IncrementalTest.extraTestDigestsTask.value,
       executeTests := {
         import sbt.TupleSyntax.*
         (

main/src/main/scala/sbt/Keys.scala

@@ -366,6 +366,7 @@ object Keys {
   val testResultLogger = settingKey[TestResultLogger]("Logs results after a test task completes.").withRank(DTask)
   val testGrouping = taskKey[Seq[Tests.Group]]("Collects discovered tests into groups. Whether to fork and the options for forking are configurable on a per-group basis.").withRank(BMinusTask)
   val isModule = AttributeKey[Boolean]("isModule", "True if the target is a module.", DSetting)
+  val extraTestDigests = taskKey[Seq[Digest]]("Extra digests that would invalidate test caching").withRank(DTask)
 
   // Classpath/Dependency Management Keys
   type Classpath = Def.Classpath

main/src/main/scala/sbt/internal/IncrementalTest.scala

@@ -11,7 +11,7 @@ package internal
 
 import java.io.File
 import java.util.concurrent.ConcurrentHashMap
-import Keys.{ test, compileInputs, fileConverter, fullClasspath, streams }
+import Keys.{ test, fileConverter, fullClasspath, streams }
 import sbt.Def.Initialize
 import sbt.internal.inc.Analysis
 import sbt.internal.util.Attributed
@@ -49,16 +49,7 @@ object IncrementalTest:
     val cp = (Keys.test / fullClasspath).value
     val testNames = Keys.definedTests.value.map(_.name).toVector.distinct
     val converter = fileConverter.value
-    val sv = Keys.scalaVersion.value
-    val inputs = (Keys.compile / Keys.compileInputs).value
-    // by default this captures JVM version
-    val extraInc = Keys.extraIncOptions.value
-    // throw in any information useful for runtime invalidation
-    val salt = s"""$sv
-${converter.toVirtualFile(inputs.options.classesDirectory)}
-${extraInc.mkString(",")}
-"""
-    val extra = Vector(Digest.sha256Hash(salt.getBytes("UTF-8")))
+    val extra = Keys.extraTestDigests.value
     val stamper = ClassStamper(cp, converter)
     // TODO: Potentially do something about JUnit 5 and others which might not use class name
     Map((testNames.flatMap: name =>
@@ -68,6 +59,15 @@ ${extraInc.mkString(",")}
     ): _*)
   }
 
+  def extraTestDigestsTask: Initialize[Task[Seq[Digest]]] = Def.cachedTask {
+    // by default this captures JVM version
+    val extraInc = Keys.extraIncOptions.value
+    // throw in any information useful for runtime invalidation
+    val salt = s"""${extraInc.mkString(",")}
+"""
+    Vector(Digest.sha256Hash(salt.getBytes("UTF-8")))
+  }
+
   def selectedFilter(args: Seq[String]): Seq[String => Boolean] =
     def matches(nfs: Seq[NameFilter], s: String) = nfs.exists(_.accept(s))
     val (excludeArgs, includeArgs) = args.partition(_.startsWith("-"))