fix latex_transformer and add test

converters/latex_transformer.py

@@ -1,75 +1,75 b''
 """
 Module that allows latex output notebooks to be conditioned before
 they are converted.
 """
 from __future__ import absolute_import
 
 # Configurable traitlets
 
 # Needed to override transformer
 from .transformers import (ActivatableTransformer)
 
 class LatexTransformer(ActivatableTransformer):
     """
     Converter for latex destined documents.
     """
 
     def cell_transform(self, cell, other, index):
         """
         Apply a transformation on each cell,
 
         receive the current cell, the resource dict and the index of current cell as parameter.
 
         Returns modified cell and resource dict.
         """
         if hasattr(cell, "source") and cell.cell_type == "markdown":
             cell.source = remove_math_space(cell.source)
         return cell, other
 
 def remove_math_space(text):
     """
     Remove the space between latex math commands and enclosing $ symbols.
     """
 
     # First, scan through the markdown looking for $.  If
     # a $ symbol is found, without a preceding \, assume
     # it is the start of a math block.  UNLESS that $ is
     # not followed by another within two math_lines.
     math_regions = []
     math_lines = 0
     within_math = False
     math_start_index = 0
     ptext = ''
     last_character = ""
     skip = False
     for index, char in enumerate(text):
         #Make sure the character isn't preceeded by a backslash
         if (char == "$" and last_character != "\\"):
             # Close the math region if this is an ending $
             if within_math:
                 within_math = False
                 skip = True
                 ptext = ptext+'$'+text[math_start_index+1:index].strip()+'$'
                 math_regions.append([math_start_index, index+1])
             else:
                 # Start a new math region
                 within_math = True
                 math_start_index = index
                 math_lines = 0
         # If we are in a math region, count the number of lines parsed.
         # Cancel the math region if we find two line breaks!
         elif char == "\n":
             if within_math:
                 math_lines += 1
                 if math_lines > 1:
                     within_math = False
-                    ptext = ptext+text[math_start_index:index]+"\n"
+                    ptext = ptext+text[math_start_index:index]
 
         # Remember the last character so we can easily watch
         # for backslashes
         last_character = char
         if not within_math and not skip:
             ptext = ptext+char
         if skip:
             skip = False
     return ptext

tests/test_transformers.py

@@ -1,25 +1,38 b''
 import io
 import nose.tools as nt
 from nose.tools import nottest
 
 from converters.latex_transformer import remove_math_space
 
 @nottest
 def test_space(input, reference):
     nt.assert_equal(remove_math_space(input),reference)
     
 
 
 def test_evens():
+    unchanged = [
+        """
+        you should be able to type
+
+            $ a single dollar and go to the line
+
+        it shouldn't be transformed.
+        """
+            ]
     references = [
             ('$e$','$e$'),
             ('$ e $','$e$'),
             ('xxx$e^i$yyy','xxx$e^i$yyy'),
             ('xxx$ e^i $yyy','xxx$e^i$yyy'),
             ('xxx$e^i $yyy','xxx$e^i$yyy'),
             ('xxx$ e^i$yyy','xxx$e^i$yyy'),
             ('\$ e $ e $','\$ e $e$'),
+            ('',''),
             ]
 
     for k,v in references :
         yield test_space, k,v
+
+    for unch in unchanged :
+        yield test_space, unch, unch