Skip some tests if nbformat not importable

Closes gh-5970

IPython/core/tests/test_magic.py

@@ -12,7 +12,7 b' from __future__ import absolute_import'
 import io
 import os
 import sys
-from unittest import TestCase
+from unittest import TestCase, skipIf
 
 try:
     from importlib import invalidate_caches   # Required from Python 3.3
@@ -28,8 +28,6 b' from IPython.core.magic import (Magics, magics_class, line_magic,'
                                 register_line_magic, register_cell_magic,
                                 register_line_cell_magic)
 from IPython.core.magics import execution, script, code
-from IPython.nbformat.v3.tests.nbexamples import nb0
-from IPython.nbformat import current
 from IPython.testing import decorators as dec
 from IPython.testing import tools as tt
 from IPython.utils import py3compat
@@ -600,37 +598,46 b' def test_extension():'
     finally:
         _ip.ipython_dir = orig_ipython_dir
         tmpdir.cleanup()
-        
-def test_notebook_export_json():
-    with TemporaryDirectory() as td:
-        outfile = os.path.join(td, "nb.ipynb")
-        _ip.ex(py3compat.u_format(u"u = {u}'héllo'"))
-        _ip.magic("notebook -e %s" % outfile)
 
-def test_notebook_export_py():
-    with TemporaryDirectory() as td:
-        outfile = os.path.join(td, "nb.py")
-        _ip.ex(py3compat.u_format(u"u = {u}'héllo'"))
-        _ip.magic("notebook -e %s" % outfile)
 
-def test_notebook_reformat_py():
-    with TemporaryDirectory() as td:
-        infile = os.path.join(td, "nb.ipynb")
-        with io.open(infile, 'w', encoding='utf-8') as f:
-            current.write(nb0, f, 'json')
-            
-        _ip.ex(py3compat.u_format(u"u = {u}'héllo'"))
-        _ip.magic("notebook -f py %s" % infile)
+# The nose skip decorator doesn't work on classes, so this uses unittest's skipIf
+@skipIf(dec.module_not_available('IPython.nbformat.current'), 'nbformat not importable')
+class NotebookExportMagicTests(TestCase):
+    def test_notebook_export_json(self):
+        with TemporaryDirectory() as td:
+            outfile = os.path.join(td, "nb.ipynb")
+            _ip.ex(py3compat.u_format(u"u = {u}'héllo'"))
+            _ip.magic("notebook -e %s" % outfile)
+
+    def test_notebook_export_py(self):
+        with TemporaryDirectory() as td:
+            outfile = os.path.join(td, "nb.py")
+            _ip.ex(py3compat.u_format(u"u = {u}'héllo'"))
+            _ip.magic("notebook -e %s" % outfile)
+
+    def test_notebook_reformat_py(self):
+        from IPython.nbformat.v3.tests.nbexamples import nb0
+        from IPython.nbformat import current
+        with TemporaryDirectory() as td:
+            infile = os.path.join(td, "nb.ipynb")
+            with io.open(infile, 'w', encoding='utf-8') as f:
+                current.write(nb0, f, 'json')
+
+            _ip.ex(py3compat.u_format(u"u = {u}'héllo'"))
+            _ip.magic("notebook -f py %s" % infile)
+
+    def test_notebook_reformat_json(self):
+        from IPython.nbformat.v3.tests.nbexamples import nb0
+        from IPython.nbformat import current
+        with TemporaryDirectory() as td:
+            infile = os.path.join(td, "nb.py")
+            with io.open(infile, 'w', encoding='utf-8') as f:
+                current.write(nb0, f, 'py')
+
+            _ip.ex(py3compat.u_format(u"u = {u}'héllo'"))
+            _ip.magic("notebook -f ipynb %s" % infile)
+            _ip.magic("notebook -f json %s" % infile)
 
-def test_notebook_reformat_json():
-    with TemporaryDirectory() as td:
-        infile = os.path.join(td, "nb.py")
-        with io.open(infile, 'w', encoding='utf-8') as f:
-            current.write(nb0, f, 'py')
-            
-        _ip.ex(py3compat.u_format(u"u = {u}'héllo'"))
-        _ip.magic("notebook -f ipynb %s" % infile)
-        _ip.magic("notebook -f json %s" % infile)
 
 def test_env():
     env = _ip.magic("env")

IPython/core/tests/test_run.py

@@ -371,7 +371,8 b' tclass.py: deleting object: C-third'
         
         with tt.AssertNotPrints('SystemExit'):
             _ip.magic('run -e %s' % self.fname)
-    
+
+    @dec.skip_without('IPython.nbformat.current')  # Requires jsonschema
     def test_run_nb(self):
         """Test %run notebook.ipynb"""
         from IPython.nbformat import current

IPython/terminal/tests/test_help.py

@@ -12,6 +12,7 b''
 #-----------------------------------------------------------------------------
 
 import IPython.testing.tools as tt
+from IPython.testing.decorators import skip_without
 
 #-----------------------------------------------------------------------------
 # Tests
@@ -36,5 +37,6 b' def test_locate_help():'
 def test_locate_profile_help():
     tt.help_all_output_test("locate profile")
 
+@skip_without('IPython.nbformat.current')  # Requires jsonschema to be installed
 def test_trust_help():
     tt.help_all_output_test("trust")