add (failling) roundtrip test case

IPython/html/tests/casperjs/test_cases/nb_roundtrip.js

@@ -7,7 +7,7 b' casper.notebook_test(function () {'
         // "we have to make messes to find out who we are"
         cell.set_text([
             "%%javascript",
-            "IPython.notebook.insert_cell_above('code')"
+            "IPython.notebook.insert_cell_below('code')"
             ].join('\n')
             );
 
@@ -17,14 +17,36 b' casper.notebook_test(function () {'
     this.wait_for_output(0);
 
     this.then(function ( ) {
-        var result = this.get_output_cell(1);
+        var result = this.get_output_cell(0);
         var num_cells = this.get_cells_length();
         this.test.assertEquals(num_cells, 2, '%%javascript magic works');
-        this.test.assertTrue(result.hasOwnProperty('application/javascript'), 'JS embeded with mime key');
+        this.test.assertTrue(result.hasOwnProperty('application/javascript'),
+            'JS embeded with mime key');
     });
 
+    //this.thenEvaluate(function() { IPython.notebook.save_notebook(); });
+
+    this.then(function ( ) {
+        json = this.evaluate(function() {
+            // the appended cell will initiall be empty
+            var json = IPython.notebook.get_cell(0).output_area.toJSON();
+            var cell = IPython.notebook.get_cell(1).output_area.fromJSON(json);
+            return json;
+        });
+        var result = this.get_output_cell(0);
+        var result2 = this.get_output_cell(1);
+        this.test.assertTrue(result.hasOwnProperty('application/javascript'),
+            'embeded JS keeps mime key after save');
+        this.test.assertTrue(json[0].hasOwnProperty('javascript'),
+            'JSON representation uses short keys');
+        this.test.assertTrue(result2.hasOwnProperty('application/javascript'),
+            'embeded JS keeps mime key on fromJSON');
+
+    });
 
-    //this.thenEvaluate(function () { var cell = IPython.notebook.get_cell(0);
+
+    //this.thenEvaluate(function () { 
+    //var cell = IPython.notebook.get_cell(0);
 
     //    // we have to make messes to find out who we are
     //    cell.set_text([
@@ -38,11 +60,4 b' casper.notebook_test(function () {'
     //
     //this.wait_for_output(0);
 
-    //this.then(function ( ) {
-    //    var result = this.get_output_cell(0);
-    //    var num_cells = this.get_cells_length();
-    //    this.test.assertEquals(result.text, '10\n', 'opening notebook JSON');
-    //    this.test.assertEquals(num_cells, 2, '              %%javascript magic works')
-    //});
-
 });