Merge pull request #9427 from da-tubi/test/constantFolder

test/junit/scala/tools/nsc/typechecker/ConstantFolderTest.scala

@@ -0,0 +1,65 @@
+package scala.tools.nsc.typechecker
+
+import org.junit.Test
+import org.junit.Assert.assertTrue
+
+import scala.tools.testkit.BytecodeTesting
+
+
+class ConstantFolderTest extends BytecodeTesting {
+  import compiler._
+  import global._
+
+  override def compilerArgs = "-Ystop-after:typer"
+
+  def literalValDefAssert(tree: Tree, name: String, constant: Constant): Unit = {
+    val valDef: ValDef = tree.collect {
+      case node @ ValDef(_, _, _, _) if node.name.decodedName.toString.trim == name =>
+        node
+    }.head
+
+    assertTrue {
+      valDef.collect { case node @ Literal(constant) => node }.nonEmpty
+    }
+  }
+
+  @Test
+  def testStringFolder(): Unit = {
+    val code =
+      """object O {
+        |  final val x = "123" + "Scala"
+        |}
+      """.stripMargin
+    val run = compiler.newRun()
+    run.compileSources(List(BytecodeTesting.makeSourceFile(code, "UnitTestSource.scala")))
+    val tree = run.units.next().body
+    literalValDefAssert(tree, "x", Constant("123Scala"))
+  }
+
+  @Test
+  def testBooleanFolder(): Unit = {
+    val code =
+      """object O {
+        |  final val x0 = true && true
+        |  final val x1 = true && false
+        |  final val x2 = false && true
+        |  final val x3 = false && false
+        |  final val x4 = true || true
+        |  final val x5 = true || false
+        |  final val x6 = false || true
+        |  final val x7 = false || false
+        |}
+      """.stripMargin
+    val run = compiler.newRun()
+    run.compileSources(List(BytecodeTesting.makeSourceFile(code, "UnitTestSource.scala")))
+    val tree = run.units.next().body
+    literalValDefAssert(tree, "x0", Constant(true))
+    literalValDefAssert(tree, "x1", Constant(false))
+    literalValDefAssert(tree, "x2", Constant(false))
+    literalValDefAssert(tree, "x3", Constant(false))
+    literalValDefAssert(tree, "x4", Constant(true))
+    literalValDefAssert(tree, "x5", Constant(true))
+    literalValDefAssert(tree, "x6", Constant(true))
+    literalValDefAssert(tree, "x7", Constant(false))
+  }
+}