move to ScalaTest 3.2 (and narrower dependencies)

Author: SethTisue

build.sbt

@@ -7,7 +7,10 @@ lazy val swing = project.in(file("."))
     scalaModuleMimaPreviousVersion := Some("2.1.0"),
     // set the prompt (for this build) to include the project id.
     shellPrompt in ThisBuild := { state => Project.extract(state).currentRef.project + "> " },
-    libraryDependencies += "org.scalatest" %% "scalatest" % "3.0.8" % Test,
+    libraryDependencies ++= Seq(
+      "org.scalatest" %% "scalatest-flatspec" % "3.2.0" % Test,
+      "org.scalatest" %% "scalatest-shouldmatchers" % "3.2.0" % Test,
+    ),
     // Adds a `src/main/scala-2.13+` source directory for Scala 2.13 and newer
     // and  a `src/main/scala-2.13-` source directory for Scala version older than 2.13
     unmanagedSourceDirectories in Compile += {

src/test/scala/scala/swing/Issue73.scala

@@ -1,8 +1,9 @@
 package scala.swing
 
-import org.scalatest.{FlatSpec, Matchers}
+import org.scalatest.flatspec.AnyFlatSpec
+import org.scalatest.matchers.should.Matchers
 
-class Issue73 extends FlatSpec with Matchers {
+class Issue73 extends AnyFlatSpec with Matchers {
   "Enumerations" should "not contain duplicate ids" in {
     // the initializers of any of these will through an
     // assertion error if an enumeration `Value` id is used twice.

src/test/scala/scala/swing/Issue97.scala

@@ -2,15 +2,16 @@ package scala.swing
 
 import java.util.concurrent.TimeUnit
 
-import org.scalatest.{FlatSpec, Matchers}
+import org.scalatest.flatspec.AnyFlatSpec
+import org.scalatest.matchers.should.Matchers
 
 import scala.concurrent.duration.Duration
 import scala.concurrent.{Await, Future, Promise}
 import scala.swing.event.{UIElementHidden, UIElementMoved, UIElementResized, UIElementShown}
 import scala.util.control.NonFatal
 
 // Note: `AsyncFlatSpec` has issues with swallowing errors and returning early.
-class Issue97 extends FlatSpec with Matchers {
+class Issue97 extends AnyFlatSpec with Matchers {
   case class Count(shown: Int = 0, hidden: Int = 0, moved: Int = 0, resized: Int = 0)
 
   def countEvents(): Future[Count] = {