[GR-15575] Add a test for requiring a gem from the Context API.

PullRequest: truffleruby/873

Author: eregon

src/test/java/org/truffleruby/ContextPermissionsTest.java

@@ -38,6 +38,21 @@ public void testNativeNoThreads() throws Throwable {
         }
     }
 
+    @Test
+    public void testRequireGem() {
+        // TODO (eregon, 4 Feb 2019): This should run on GraalVM, not development jars
+        String home = System.getProperty("user.dir") + "/mxbuild/truffleruby-jvm/jre/languages/ruby";
+        try (Context context = Context.newBuilder("ruby")
+                .allowIO(true)
+                .allowNativeAccess(true)
+                .allowExperimentalOptions(true)
+                .option("ruby.home", home)
+                .build()) {
+            // NOTE: rake is a bundled gem, so it needs RubyGems to be required
+            Assert.assertEquals("Rake", context.eval("ruby", "require 'rake'; Rake.to_s").asString());
+        }
+    }
+
     @Test
     public void testThreadsNoNative() throws Throwable {
         // The ruby.single_threaded option needs to be set because --single-threaded defaults to --embedded.