BLD: Test for Python 3.5 with C locale

xref #12337

Author: Nicolas Bonnotte <nicolas.bonnotte@gmail.com>

Closes #14114 from nbonnotte/unicode-to_latex-12337 and squashes the following commits:

dadf73c [Nicolas Bonnotte] New tentative with C locale
b876296 [Nicolas Bonnotte] Base matrix configuration
c825f86 [Nicolas Bonnotte] New files requirements-3.5_ASCII.*
3b4c6a5 [Nicolas Bonnotte] Travis conf: new test with python 3.5 and LC_ALL=C
3b859ce [Nicolas Bonnotte] Test for Python 3.4 with C locale

.travis.yml

@@ -153,6 +153,15 @@ matrix:
         apt:
           packages:
           - language-pack-it
+#    In allow_failures
+    - python: 3.5
+      env:
+        - JOB_NAME: "35_ascii"
+        - JOB_TAG=_ASCII
+        - NOSE_ARGS="not slow and not network and not disabled"
+        - LOCALE_OVERRIDE="C"
+        - CACHE_NAME="35_ascii"
+        - USE_CACHE=true
 #    In allow_failures
     - python: 2.7
       env:
@@ -219,6 +228,14 @@ matrix:
           apt:
             packages:
             - language-pack-it
+      - python: 3.5
+        env:
+        - JOB_NAME: "35_ascii"
+        - JOB_TAG=_ASCII
+        - NOSE_ARGS="not slow and not network and not disabled"
+        - LOCALE_OVERRIDE="C"
+        - CACHE_NAME="35_ascii"
+        - USE_CACHE=true
       - python: 2.7
         env:
         - JOB_NAME: "doc_build"

ci/requirements-3.5_ASCII.build

@@ -0,0 +1,4 @@
+python-dateutil
+pytz
+numpy
+cython

ci/requirements-3.5_ASCII.run

@@ -0,0 +1,3 @@
+python-dateutil
+pytz
+numpy

pandas/tests/formats/test_format.py

@@ -2820,7 +2820,7 @@ def test_to_latex_filename(self):
                 self.assertEqual(df.to_latex(), f.read())
 
         # test with utf-8 without encoding option
-        if compat.PY3:  # python3 default encoding is utf-8
+        if compat.PY3:  # python3: pandas default encoding is utf-8
             with tm.ensure_clean('test.tex') as path:
                 df.to_latex(path)
                 with codecs.open(path, 'r') as f:
@@ -4295,7 +4295,7 @@ def format_func(x):
         formatter = fmt.Datetime64Formatter(x, formatter=format_func)
         result = formatter.get_result()
         self.assertEqual(result, ['2016-01', '2016-02'])
-                       
+
     def test_datetime64formatter_hoursecond(self):
 
         x = Series(pd.to_datetime(['10:10:10.100', '12:12:12.120'],

pandas/tools/tests/test_util.py

@@ -68,10 +68,12 @@ def test_set_locale(self):
             raise nose.SkipTest("Only a single locale found, no point in "
                                 "trying to test setting another locale")
 
-        if LOCALE_OVERRIDE is not None:
-            lang, enc = LOCALE_OVERRIDE.split('.')
-        else:
+        if LOCALE_OVERRIDE is None:
             lang, enc = 'it_CH', 'UTF-8'
+        elif LOCALE_OVERRIDE == 'C':
+            lang, enc = 'en_US', 'ascii'
+        else:
+            lang, enc = LOCALE_OVERRIDE.split('.')
 
         enc = codecs.lookup(enc).name
         new_locale = lang, enc