Add missing class.

lib_xunit/src/main/x/xunit/executor.x

@@ -3,4 +3,10 @@
  * execution of test fixtures.
  */
 package executor {
+    /**
+     * A skipped test result.
+     */
+	const SkipResult(Boolean skipped, String reason = "unknown") {
+	    static SkipResult NotSkipped = new SkipResult(False);
+    }
 }

lib_xunit/src/main/x/xunit/executor/DefaultEngine.x

@@ -0,0 +1,15 @@
+/**
+ * A default `TestEngine` implementation.
+ */
+service DefaultEngine
+        implements TestEngine {
+    @Override
+    Model discover(DiscoveryConfiguration config, Selector[] selectors) {
+        TODO
+    }
+
+    @Override
+    void execute(Model model) {
+        TODO
+    }
+}

manualTests/src/main/x/xunit/xunit_test/executor/DefaultMethodExecutorTest.x

@@ -32,7 +32,7 @@ class DefaultMethodExecutorTest {
         ExecutionContext ctx      = DefaultExecutionContext.create(model);
         ResolverStub     resolver = new ResolverStub(["Foo", "Bar"]);
 
-        ctx.repository.register(ParameterResolver, resolver);
+        ctx.registry.register(ParameterResolver, resolver);
 
         DefaultMethodExecutor executor = new DefaultMethodExecutor();
         Tuple                 result   = executor.invoke(fn, ctx);