Add regression test for issue 18726

presentation-compiler/test/dotty/tools/pc/base/ReusableClassRunner.scala

@@ -13,22 +13,17 @@ class ReusableClassRunner(testClass: Class[BasePCSuite])
     testClass.getDeclaredConstructor().newInstance()
 
   override def createTest(): AnyRef = instance
-  override def withBefores(
-      method: FrameworkMethod,
-      target: Object,
-      statement: Statement
-  ): Statement =
-    statement
 
   override def withAfters(
       method: FrameworkMethod,
       target: Object,
       statement: Statement
   ): Statement =
+    val newStatement = super.withAfters(method, target, statement)
     new Statement():
       override def evaluate(): Unit =
         try
-          statement.evaluate()
+          newStatement.evaluate()
         finally
           if (isLastTestCase(method)) then instance.clean()
 

presentation-compiler/test/dotty/tools/pc/tests/completion/CompletionRelease11Suite.scala

@@ -0,0 +1,32 @@
+package dotty.tools.pc.tests.completion
+
+import dotty.tools.pc.base.BaseCompletionSuite
+
+import org.junit.Test
+import org.junit.Before
+import java.nio.file.Path
+import dotty.tools.pc.utils.JRE
+
+class CompletionRelease11Suite extends BaseCompletionSuite:
+
+  override protected def scalacOptions(classpath: Seq[Path]): Seq[String] =
+    "-release:11" +: super.scalacOptions(classpath)
+
+  @Before
+  def beforeMethod(): Unit =
+    org.junit.Assume.assumeTrue(JRE.getJavaMajorVersion >= 11)
+
+  @Test def java11Symbols =
+    check(
+      """
+        |object A {
+        |  "".repea@@
+        |}""".stripMargin,
+      """repeat(x$0: Int): String
+        |replaceAll(x$0: String, x$1: String): String
+        |prependedAll[B >: A](prefix: IterableOnce[B]): IndexedSeq[B]
+        |prependedAll(prefix: String): String
+        |prependedAll[B >: Char](prefix: IterableOnce[B]): IndexedSeq[B]
+        |replaceAllLiterally(literal: String, replacement: String): String
+        |""".stripMargin
+    )

presentation-compiler/test/dotty/tools/pc/tests/completion/CompletionRelease8Suite.scala

@@ -0,0 +1,31 @@
+package dotty.tools.pc.tests.completion
+
+import dotty.tools.pc.base.BaseCompletionSuite
+
+import org.junit.Test
+import org.junit.Before
+import java.nio.file.Path
+import dotty.tools.pc.utils.JRE
+
+class CompletionRelease8Suite extends BaseCompletionSuite:
+
+  override protected def scalacOptions(classpath: Seq[Path]): Seq[String] =
+    "-release:8" +: super.scalacOptions(classpath)
+
+  @Before
+  def beforeMethod(): Unit =
+    org.junit.Assume.assumeTrue(JRE.getJavaMajorVersion >= 8)
+
+  @Test def noJvm11Symbols =
+    check(
+      """
+        |object A {
+        |  "".repea@@
+        |}""".stripMargin,
+      """replaceAll(x$0: String, x$1: String): String
+        |prependedAll[B >: A](prefix: IterableOnce[B]): IndexedSeq[B]
+        |prependedAll(prefix: String): String
+        |prependedAll[B >: Char](prefix: IterableOnce[B]): IndexedSeq[B]
+        |replaceAllLiterally(literal: String, replacement: String): String
+        |""".stripMargin
+    )

presentation-compiler/test/dotty/tools/pc/utils/JRE.scala

@@ -0,0 +1,22 @@
+package dotty.tools.pc.utils
+
+object JRE:
+
+  def getJavaMajorVersion: Int =
+    val javaVersion = sys.env.get("java.version").filter(!_.isEmpty())
+
+    javaVersion match
+      case Some(version) if version.startsWith("1.8") => 8
+      case _ =>
+        scala.util.Try:
+          val versionMethod = classOf[Runtime].getMethod("version")
+          versionMethod.nn.setAccessible(true)
+          val version = versionMethod.nn.invoke(null)
+
+          val majorMethod = version.getClass().getMethod("feature")
+          majorMethod.nn.setAccessible(true)
+          val major = majorMethod.nn.invoke(version).asInstanceOf[Int]
+          major
+        .getOrElse(8) // Minimal version supported by Scala
+
+