MRG: fix for doctest errors on Python 3.5

.travis.yml

@@ -26,6 +26,7 @@ python:
     - 3.2
     - 3.3
     - 3.4
+    - 3.5
 matrix:
   include:
     - python: 2.7
@@ -44,11 +45,13 @@ matrix:
       env:
         - DOC_DOC_TEST=1
 before_install:
+    - source tools/travis_tools.sh
     - virtualenv --python=python venv
     - source venv/bin/activate
     - python --version # just to check
-    - pip install nose # always
-    - pip install --no-index -f http://travis-wheels.scikit-image.org $DEPENDS
+    - pip install -U pip  # upgrade to latest pip to find 3.5 wheels
+    - retry pip install nose # always
+    - wheelhouse_pip_install $DEPENDS
     # pydicom <= 0.9.8 doesn't install on python 3
     - if [ "${TRAVIS_PYTHON_VERSION:0:1}" == "2" ]; then
         if [ "$PYDICOM" == "1" ]; then

Changelog

@@ -34,6 +34,12 @@ References like "pr/298" refer to github pull request numbers.
     are raising a DataError if the track is truncated when ``strict=True``
     (the default), rather than a TypeError when trying to create the points
     array.
+  * tripwire.TripWire object now raises subclass of AttributeError when trying
+    to get an attribute, rather than a direct subclass of Exception.  This
+    prevents Python 3.5 triggering the tripwire when doing inspection prior to
+    running doctests.
+  * Minor API change for tripwire.TripWire object; code that checked for
+    AttributeError will now also catch TripWireError.
 
 * 2.0.1 (Saturday 27 June 2015)
 

nibabel/tests/test_tripwire.py

@@ -0,0 +1,29 @@
+""" Testing tripwire module
+"""
+
+from ..tripwire import TripWire, is_tripwire, TripWireError
+
+from nose import SkipTest
+from nose.tools import (assert_true, assert_false, assert_raises,
+                        assert_equal, assert_not_equal)
+
+
+def test_is_tripwire():
+    assert_false(is_tripwire(object()))
+    assert_true(is_tripwire(TripWire('some message')))
+
+
+def test_tripwire():
+    # Test tripwire object
+    silly_module_name = TripWire('We do not have silly_module_name')
+    assert_raises(TripWireError,
+                  getattr,
+                  silly_module_name,
+                  'do_silly_thing')
+    # Check AttributeError can be checked too
+    try:
+        silly_module_name.__wrapped__
+    except TripWireError as err:
+        assert_true(isinstance(err, AttributeError))
+    else:
+        raise RuntimeError("No error raised, but expected")

nibabel/tripwire.py

@@ -2,8 +2,12 @@
 """
 
 
-class TripWireError(Exception):
+class TripWireError(AttributeError):
     """ Exception if trying to use TripWire object """
+    # Has to be subclass of AttributeError, to work round Python 3.5 inspection
+    # for doctests.  Python 3.5 looks for a ``__wrapped__`` attribute during
+    # initialization of doctests, and only allows AttributeError as signal this
+    # is not present.
 
 
 def is_tripwire(obj):
@@ -32,14 +36,11 @@ class TripWire(object):
 
     Examples
     --------
-    >>> try:
-    ...     import silly_module_name
-    ... except ImportError:
-    ...    silly_module_name = TripWire('We do not have silly_module_name')
-    >>> silly_module_name.do_silly_thing('with silly string') #doctest: +IGNORE_EXCEPTION_DETAIL
+    >>> a_module = TripWire('We do not have a_module')
+    >>> a_module.do_silly_thing('with silly string') #doctest: +IGNORE_EXCEPTION_DETAIL
     Traceback (most recent call last):
         ...
-    TripWireError: We do not have silly_module_name
+    TripWireError: We do not have a_module
     """
     def __init__(self, msg):
         self._msg = msg

tools/travis_tools.sh

@@ -0,0 +1,26 @@
+# Tools for working with travis-ci
+export WHEELHOST="travis-wheels.scikit-image.org"
+export WHEELHOUSE="http://${WHEELHOST}/"
+
+retry () {
+    # https://gist.github.com/fungusakafungus/1026804
+    local retry_max=5
+    local count=$retry_max
+    while [ $count -gt 0 ]; do
+        "$@" && break
+        count=$(($count - 1))
+        sleep 1
+    done
+
+    [ $count -eq 0 ] && {
+        echo "Retry failed [$retry_max]: $@" >&2
+        return 1
+    }
+    return 0
+}
+
+
+wheelhouse_pip_install() {
+    # Install pip requirements via travis wheelhouse
+    retry pip install --timeout=60 --no-index --trusted-host $WHEELHOST --find-links $WHEELHOUSE $@
+}