Really check the file extension, not an arbitrary occurrence of 'rst'.

tests/test_simple.py

@@ -1,70 +1,70 b''
 from nbconvert import ConverterRST, main
 import nose.tools as nt
 
 import os
 import glob
 from IPython.nbformat import current as nbformat
 
 fname = 'tests/test.ipynb'
 out_fname = 'tests/test.rst'
 
 
 def clean_dir():
     "Remove .rst files created during conversion"
     map(os.remove, glob.glob("./tests/*.rst"))
     map(os.remove, glob.glob("./tests/*.png"))
     map(os.remove, glob.glob("./tests/*.html"))
     map(os.remove, glob.glob("./tests/test_files/*"))
 
 
 @nt.with_setup(clean_dir, clean_dir)
 def test_simple():
     c = ConverterRST(fname)
     f = c.render()
-    nt.assert_true('rst' in f, 'changed file extension to rst')
+    nt.assert_true(f.endswith('.rst'), 'changed file extension to rst')
 
 
 @nt.with_setup(clean_dir, clean_dir)
 def test_main():
     """
     Test main entry point
     """
     main(fname)
     nt.assert_true(os.path.exists(out_fname))
 
 
 def test_render_heading():
     """ Unit test for cell type "heading" """
     # Generate and test heading cells level 1-6
     for level in xrange(1, 7):
         cell = {
             'cell_type': 'heading',
             'level'    : level,
             'source'   :  ['Test for heading type H{0}'.format(level)]
             }
         # Convert cell dictionaries to NotebookNode
         cell_nb = nbformat.NotebookNode(cell)
         # Make sure "source" attribute is uniconde not list.
         # For some reason, creating a NotebookNode manually like
         # this isn't converting source to a string like using
         # the create-from-file routine.
         if type(cell_nb.source) is list:
             cell_nb.source = '\n'.join(cell_nb.source)
         # Render to rst
         c = ConverterRST('')
         rst_list = c.render_heading(cell_nb)
         nt.assert_true(isinstance(rst_list, list))  # render should return a list
         rst_str = "".join(rst_list)
         # Confirm rst content
         chk_str = "Test for heading type H{0}\n{1}\n".format(
              level, c.heading_level[level] * 24)
         nt.assert_equal(rst_str, chk_str)
 
 
 @nt.with_setup(clean_dir, clean_dir)
 def test_main_html():
     """
     Test main entry point
     """
     main(fname, format='html')
     nt.assert_true(os.path.exists('tests/test.html'))