blackBox() infrastructure

idea/testData/codegen/inheritance.jet

@@ -9,3 +9,7 @@ class P1(x : Int, y : Y) : Abstract, X(x), Y by y {}
 class P2(x : Int, y : Y) : X(x), Abstract, Y by y {}
 class P3(x : Int, y : Y) : X(x), Y by y, Abstract {}
 class P4(x : Int, y : Y) : Y by y, Abstract, X(x) {}
+
+fun box() : String {
+    "OK"
+}

idea/tests/org/jetbrains/jet/codegen/ClassGenTest.java

@@ -23,14 +23,12 @@ public class ClassGenTest extends CodegenTestCase {
         final Class aClass = loadClass("Foo", generateClassesInFile());
         checkInterface(aClass, List.class);
     }
+
     public void testArrayInheritance() throws Exception {
         loadFile("inheritance.jet");
         System.out.println(generateToText());
 
-/*
-        final Class aClass = loadClass("Foo", generateClassesInFile());
-        checkInterface(aClass, List.class);
-*/
+        assertEquals("OK", blackBox());
     }
 
     private static void checkInterface(Class aClass, Class ifs) {

idea/tests/org/jetbrains/jet/codegen/CodegenTestCase.java

@@ -40,6 +40,18 @@ public abstract class CodegenTestCase extends LightCodeInsightFixtureTestCase {
         myFixture.configureByFile(JetParsingTest.getTestDataDir() + "/codegen/" + name);
     }
 
+    protected String blackBox() throws Exception {
+        Codegens codegens = generateClassesInFile();
+        CodegensClassLoader loader = new CodegensClassLoader(codegens);
+
+        JetFile jetFile = (JetFile) myFixture.getFile();
+        final JetNamespace namespace = jetFile.getRootNamespace();
+        String fqName = NamespaceCodegen.getJVMClassName(namespace.getFQName()).replace("/", ".");
+        Class<?> namespaceClass = loader.loadClass(fqName);
+        Method method = namespaceClass.getMethod("box");
+        return (String) method.invoke(null);
+    }
+
     protected String generateToText() {
         Codegens state = new Codegens(getProject(), true);
         JetFile jetFile = (JetFile) myFixture.getFile();
@@ -144,6 +156,25 @@ public abstract class CodegenTestCase extends LightCodeInsightFixtureTestCase {
       }
     }
 
+    private static class CodegensClassLoader extends ClassLoader {
+        private final Codegens state;
+
+        public CodegensClassLoader(Codegens state) {
+            super(CodegenTestCase.class.getClassLoader());
+            this.state = state;
+        }
+
+        @Override
+        protected Class<?> findClass(String name) throws ClassNotFoundException {
+            String file = name.replace('.', '/') + ".class";
+            if (state.files().contains(file)) {
+                byte[] bytes = state.asBytes(file);
+                return defineClass(name, bytes, 0, bytes.length);
+            }
+            return super.findClass(name);
+        }
+    }
+
     @NotNull
     @Override
     protected LightProjectDescriptor getProjectDescriptor() {