testing roundtrip of test.ipynb file after passing through json.dump/json.load

tests/test_nbconverter.py

@@ -1,10 +1,10 b''
 from nbconvert import ConverterNotebook
 import nose.tools as nt
-import os
+import os, json
 
 fname = 'tests/test.ipynb'
 outbase1 = 'newtest1'
-outbase2 = 'newtest2'
+outbase2 = 'test' # will output to ./test.ipynb
 
 def test_roundtrip():
     converter = ConverterNotebook(fname, outbase1)
@@ -18,3 +18,7 b' def test_roundtrip():'
     nt.assert_true(s1.replace(outbase1, outbase2) == s2)
     os.remove(outbase1+'.ipynb')
     os.remove(outbase2+'.ipynb')
+
+    s0 = json.dumps(json.load(file(fname)), indent=1, sort_keys=True)
+    nt.assert_true(s0 == s2)
+