Fix Mill export for projects with just the test scope (#3046)

* Fix Mill export for projects with just the test scope

* Increase integration test timeouts to 300s

Author: Gedochao

modules/cli/src/main/scala/scala/cli/exportCmd/MillProjectDescriptor.scala

@@ -33,8 +33,8 @@ final case class MillProjectDescriptor(
 
     val pureJava = !options.scalaOptions.addScalaLibrary.contains(true) &&
       !options.scalaOptions.addScalaCompiler.contains(true) &&
-      sources.paths.forall(_._1.last.endsWith(".java")) &&
-      sources.inMemory.forall(_.generatedRelPath.last.endsWith(".java")) &&
+      sources.hasJava &&
+      !sources.hasScala &&
       options.classPathOptions.allExtraDependencies.toSeq
         .forall(_.value.nameAttributes == NoAttributes)
 

modules/integration/src/test/scala/scala/cli/integration/ExportCommonTestDefinitions.scala

@@ -96,6 +96,18 @@ trait ExportCommonTestDefinitions { _: ScalaCliSuite & TestScalaVersionArgs =>
     }
   }
 
+  def justTestScope(): Unit = {
+    val expectedMessage = "exporting just the test scope actually works!"
+    prepareTestInputs(ExportTestProjects.justTestScope(expectedMessage))
+      .fromRoot { root =>
+        exportCommand(".").call(cwd = root)
+        val testRes = buildToolCommand(root, runTestsArgs*)
+          .call(cwd = root / outputDir)
+        val testOutput = testRes.out.text()
+        expect(testOutput.contains(expectedMessage))
+      }
+  }
+
   private val scalaVersionsInDir: Seq[String] = Seq("2.12", "2.13", "2", "3", "3.lts")
 
   if (runExportTests) {
@@ -123,5 +135,9 @@ trait ExportCommonTestDefinitions { _: ScalaCliSuite & TestScalaVersionArgs =>
       }
     }
 
+    test("just test scope") {
+      justTestScope()
+    }
+
   }
 }

modules/integration/src/test/scala/scala/cli/integration/ExportTestProjects.scala

@@ -2,6 +2,8 @@ package scala.cli.integration
 
 import com.eed3si9n.expecty.Expecty.expect
 
+import scala.cli.integration.Constants.munitVersion
+
 object ExportTestProjects {
   def jvmTest(scalaVersion: String): TestInputs = {
 
@@ -324,4 +326,17 @@ object ExportTestProjects {
            |}
            |""".stripMargin
     )
+
+  def justTestScope(msg: String): TestInputs = TestInputs(
+    os.rel / "MyTests.test.scala" ->
+      s"""//> using dep org.scalameta::munit::$munitVersion
+         |
+         |class MyTests extends munit.FunSuite {
+         |  test("foo") {
+         |    assert(2 + 2 == 4)
+         |    println("$msg")
+         |  }
+         |}
+         |""".stripMargin
+  )
 }

modules/integration/src/test/scala/scala/cli/integration/ScalaCliSuite.scala

@@ -23,7 +23,7 @@ abstract class ScalaCliSuite extends munit.FunSuite {
     }
   }
 
-  override def munitTimeout: Duration = new FiniteDuration(240, TimeUnit.SECONDS)
+  override def munitTimeout: Duration = new FiniteDuration(300, TimeUnit.SECONDS)
 
   override def munitFixtures: List[Fixture[Unit]] = List(testStartEndLogger)
   def group: ScalaCliSuite.TestGroup              = ScalaCliSuite.TestGroup.Third