move assert_big_text_equal to nbconvert

where it's used

IPython/testing/tools.py

@@ -465,23 +465,3 b" def help_all_output_test(subcommand=''):"
     nt.assert_in("Class parameters", out)
     return out, err
 
-def assert_big_text_equal(a, b, chunk_size=80):
-    """assert that large strings are equal
-
-    Zooms in on first chunk that differs,
-    to give better info than vanilla assertEqual for large text blobs.
-    """
-    for i in range(0, len(a), chunk_size):
-        chunk_a = a[i:i + chunk_size]
-        chunk_b = b[i:i + chunk_size]
-        nt.assert_equal(chunk_a, chunk_b, "[offset: %i]\n%r != \n%r" % (
-            i, chunk_a, chunk_b))
-
-    if len(a) > len(b):
-        nt.fail("Length doesn't match (%i > %i). Extra text:\n%r" % (
-            len(a), len(b), a[len(b):]
-        ))
-    elif len(a) < len(b):
-        nt.fail("Length doesn't match (%i < %i). Extra text:\n%r" % (
-            len(a), len(b), b[len(a):]
-        ))

jupyter_nbconvert/exporters/tests/test_notebook.py

@@ -9,7 +9,7 b' from .base import ExportersTestsBase'
 from ..notebook import NotebookExporter
 
 from IPython.nbformat import validate
-from IPython.testing.tools import assert_big_text_equal
+from jupyter_nbconvert.tests.base import assert_big_text_equal
 
 class TestNotebookExporter(ExportersTestsBase):
     """Contains test functions for notebook.py"""

jupyter_nbconvert/tests/base.py

@@ -11,10 +11,12 b' import shutil'
 import sys
 import unittest
 
+import nose.tools as nt
+
 from IPython.nbformat import v4, write
 from IPython.utils.tempdir import TemporaryWorkingDirectory
 from IPython.utils.process import get_output_error_code
-
+from IPython.utils.py3compat import string_types
 
 class TestsBase(unittest.TestCase):
     """Base tests class.  Contains useful fuzzy comparison and nbconvert
@@ -143,3 +145,24 b' class TestsBase(unittest.TestCase):'
         if not (retcode == 0 or ignore_return_code):
             raise OSError(stderr)
         return stdout, stderr
+    
+def assert_big_text_equal(a, b, chunk_size=80):
+    """assert that large strings are equal
+
+    Zooms in on first chunk that differs,
+    to give better info than vanilla assertEqual for large text blobs.
+    """
+    for i in range(0, len(a), chunk_size):
+        chunk_a = a[i:i + chunk_size]
+        chunk_b = b[i:i + chunk_size]
+        nt.assert_equal(chunk_a, chunk_b, "[offset: %i]\n%r != \n%r" % (
+            i, chunk_a, chunk_b))
+
+    if len(a) > len(b):
+        nt.fail("Length doesn't match (%i > %i). Extra text:\n%r" % (
+            len(a), len(b), a[len(b):]
+        ))
+    elif len(a) < len(b):
+        nt.fail("Length doesn't match (%i < %i). Extra text:\n%r" % (
+            len(a), len(b), b[len(a):]
+        ))