Factor basic JSEnv tests in trait

Author: gzm0

js-envs/src/test/scala/org/scalajs/jsenv/test/AsyncTests.scala

@@ -13,7 +13,7 @@ import scala.concurrent.Await
 import scala.concurrent.duration._
 
 /** A couple of tests that test async runners for mix-in into a test suite */
-trait AsyncTests {
+trait AsyncTests extends BasicJSEnvTests {
 
   protected final val DefaultTimeout: Duration = 10.seconds
 

js-envs/src/test/scala/org/scalajs/jsenv/test/BasicJSEnvTests.scala

@@ -0,0 +1,28 @@
+package org.scalajs.jsenv.test
+
+import org.junit.Test
+import org.junit.Assert._
+
+/** Tests that should succeed on any JSEnv */
+trait BasicJSEnvTests extends JSEnvTest {
+
+  @Test
+  def failureTest: Unit = {
+
+    """
+    var a = {};
+    a.foo();
+    """.fails()
+
+  }
+
+  @Test
+  def syntaxErrorTest: Unit = {
+
+    """
+    {
+    """.fails()
+
+  }
+
+}