[BSP] Fix importing Optional project dependency

main/src/main/scala/sbt/internal/InternalDependencies.scala

@@ -13,7 +13,9 @@ import sbt.Keys._
 
 private[sbt] object InternalDependencies {
   def configurations: Def.Initialize[Seq[(ProjectRef, Set[String])]] = Def.setting {
-    val allConfigs = Classpaths.allConfigs(configuration.value).map(_.name).toSet
+    val configMap = internalConfigurationMap.value
+    val config = configMap(configuration.value)
+    val allConfigs = Classpaths.allConfigs(config).map(_.name).toSet
     val ref = thisProjectRef.value
     val projectDependencies = buildDependencies.value.classpath.get(ref).toSeq.flatten
     val applicableConfigs = allConfigs + "*"

server-test/src/server-test/buildserver/build.sbt

@@ -12,7 +12,7 @@ lazy val runAndTest = project.in(file("run-and-test"))
     Test / javaOptions := Vector("Xmx512M"),
     Test / envVars := Map("KEY_TEST" -> "VALUE_TEST"),
   )
-  .dependsOn(util)
+  .dependsOn(util % Optional)
 
 lazy val reportError = project.in(file("report-error"))
 

server-test/src/test/scala/testpkg/BuildServerTest.scala

@@ -43,8 +43,12 @@ object BuildServerTest extends AbstractServerTest {
   test("workspace/buildTargets") { _ =>
     sendRequest("workspace/buildTargets")
     val result = svr.waitFor[WorkspaceBuildTargetsResult](10.seconds)
-    val utilTarget = result.targets.find(_.displayName.contains("util")).get
+    val utilTargetIdentifier = BuildTargetIdentifier(buildTargetUri("util", "Compile"))
+    val utilTarget = result.targets.find(_.id == utilTargetIdentifier).get
     assert(utilTarget.id.uri.toString.endsWith("#util/Compile"))
+    val runAndTestTarget = result.targets.find(_.displayName.contains("runAndTest")).get
+    // runAndTest should declare the dependency to util even if optional
+    assert(runAndTestTarget.dependencies.contains(utilTargetIdentifier))
     val buildServerBuildTarget =
       result.targets.find(_.displayName.contains("buildserver-build")).get
     assert(buildServerBuildTarget.id.uri.toString.endsWith("#buildserver-build"))
@@ -233,14 +237,19 @@ object BuildServerTest extends AbstractServerTest {
   }
 
   test("buildTarget/scalacOptions, buildTarget/javacOptions") { _ =>
-    val buildTarget = buildTargetUri("util", "Compile")
-    val badBuildTarget = buildTargetUri("badBuildTarget", "Compile")
+    val buildTargets = Seq(
+      buildTargetUri("util", "Compile"),
+      buildTargetUri("badBuildTarget", "Compile"),
+    )
 
-    val id1 = scalacOptions(Seq(buildTarget, badBuildTarget))
+    val id1 = scalacOptions(buildTargets)
     assertMessage(s""""id":"$id1"""", "scala-library-2.13.11.jar")()
 
-    val id2 = javacOptions(Seq(buildTarget, badBuildTarget))
+    val id2 = javacOptions(buildTargets)
     assertMessage(s""""id":"$id2"""", "scala-library-2.13.11.jar")()
+
+    val id3 = scalacOptions(Seq(buildTargetUri("runAndTest", "Compile")))
+    assertMessage(s""""id":"$id3"""", "util/target/scala-2.13/classes")()
   }
 
   test("buildTarget/cleanCache") { _ =>