Test ensuring `#use` staging object satisfies `Class.isClass`

README.traits

@@ -78,11 +78,5 @@ complete.
   improvement.  Until that time, be mindful of the performance test
   cases in the =test/perf= directory.
 
-* TODO Intermediate object as class
-  The immediate syntax---=Foo.use(T)()=---is a short-hand equivalent
-  of =Foo.use(T).extend({})()=. As such, for consistency, =Class.isA=
-  should consider the intermediate object returned by a call to =use=
-  to be a class.
-
   If we are to do so, though, we must make sure that the entire class
   API is supported.

test/Trait/DefinitionTest.js

@@ -455,4 +455,24 @@ require( 'common' ).testCase(
             Sut( dfn );
         } );
     },
+
+
+    /**
+     * The stating object rendered by `#use` calls implement the same
+     * methods as classes, and are even treated as classes when invoked
+     * using the immediate syntax (see ImmediateTest).  When defining
+     * abstract classes, staging objects may be extended as if they were
+     * classes (see AbstractTest).
+     *
+     * It makes sense for staging objects to be able to be treated as if
+     * they were classes, which demands reflection API consistency.
+     */
+    'Staging object for eventual mixin is considered to be class': function()
+    {
+        var T = this.Sut( {} );
+
+        this.assertOk(
+            this.Class.isClass( this.Class( {} ).use( T ) )
+        );
+    },
 } );