Add Python 3.7 to CI unit test matrix. (ansible#34680)

* Add Python 3.7 to CI unit test matrix.
* Fix `os.errno` reference to be `errno`.
* Update test_aci unit test for Python 3.7.

shippable.yml

@@ -14,6 +14,7 @@ matrix:
     - env: T=units/2.7
     - env: T=units/3.5
     - env: T=units/3.6
+    - env: T=units/3.7
 
     - env: T=windows/1
     - env: T=windows/2

test/units/module_utils/network/aci/test_aci.py

@@ -229,6 +229,8 @@ def test_empty_response(self):
             error_text = to_native(u"Unable to parse output as XML, see 'raw' output. None (line 0)", errors='surrogate_or_strict')
         elif PY2:
             error_text = "Unable to parse output as XML, see 'raw' output. Document is empty, line 1, column 1 (line 1)"
+        elif sys.version_info >= (3, 7):
+            error_text = to_native(u"Unable to parse output as XML, see 'raw' output. None (line 0)", errors='surrogate_or_strict')
         else:
             error_text = "Unable to parse output as XML, see 'raw' output. Document is empty, line 1, column 1 (<string>, line 1)"
 

test/units/modules/cloud/amazon/placebo_fixtures.py

@@ -1,3 +1,4 @@
+import errno
 import os
 import time
 import mock
@@ -64,7 +65,7 @@ def placeboify(request, monkeypatch):
         # make sure the directory for placebo test recordings is available
         os.makedirs(recordings_path)
     except OSError as e:
-        if e.errno != os.errno.EEXIST:
+        if e.errno != errno.EEXIST:
             raise
 
     pill = placebo.attach(session, data_path=recordings_path)