Added a what's new to help reduce possible impact for users.

Author: pelson

INSTALL

@@ -90,7 +90,7 @@ netcdf4-python (http://netcdf4-python.googlecode.com/)
     thread-safe build of HDF5 to avoid segmentation faults when using
     lazy evaluation.)
 
-cf_units v1.0 or later (https://github.com/SciTools/cf_units)
+cf_units v2.0 or later (https://github.com/SciTools/cf_units)
     CF data units handling, using udunits.
 
 setuptools v36.0 or later (http://pypi.python.org/pypi/setuptools/)

docs/iris/src/whatsnew/contributions_2.1/newfeature_2018-May-22_cf_units_2.txt

@@ -0,0 +1,4 @@
+Iris updated its cf_units dependency to cf_units v2. cf_units 2 is almost entirely backwards compatible,
+although the ability to preserve some alias calendars has been removed. For this reason, it is possible
+that NetCDF load of a variable with a "standard" calendar will result in a saved NetCDF of a "gregorian"
+calendar.

lib/iris/tests/results/nimrod/load_2flds.cml

@@ -10,7 +10,7 @@
     </attributes>
     <coords>
       <coord>
-        <dimCoord id="9c8bdf81" points="[355014.0]" shape="(1,)" standard_name="forecast_reference_time" units="Unit('hours since 1970-01-01 00:00:00', calendar='standard')" value_type="float64"/>
+        <dimCoord id="9c8bdf81" points="[355014.0]" shape="(1,)" standard_name="forecast_reference_time" units="Unit('hours since 1970-01-01 00:00:00', calendar='gregorian')" value_type="float64"/>
       </coord>
       <coord>
         <dimCoord id="a2cbc1ea" points="[9999.0]" shape="(1,)" standard_name="height" units="Unit('m')" value_type="float32">
@@ -32,7 +32,7 @@
         </dimCoord>
       </coord>
       <coord datadims="[0]">
-        <dimCoord id="cb784457" points="[355017.0, 363777.0]" shape="(2,)" standard_name="time" units="Unit('hours since 1970-01-01 00:00:00', calendar='standard')" value_type="float64"/>
+        <dimCoord id="cb784457" points="[355017.0, 363777.0]" shape="(2,)" standard_name="time" units="Unit('hours since 1970-01-01 00:00:00', calendar='gregorian')" value_type="float64"/>
       </coord>
     </coords>
     <cellMethods/>

lib/iris/tests/test_coding_standards.py

@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2013 - 2017, Met Office
+# (C) British Crown Copyright 2013 - 2018, Met Office
 #
 # This file is part of Iris.
 #

lib/iris/tests/test_pandas.py

@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2013 - 2017, Met Office
+# (C) British Crown Copyright 2013 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -101,18 +101,22 @@ def test_time_360(self):
         time_coord = DimCoord([0, 100.1, 200.2, 300.3, 400.4],
                               long_name="time", units=time_unit)
         cube.add_dim_coord(time_coord, 0)
-        if netCDF4.__version__ > '1.2.4':
+        # TODO Remove this if statement as we move to cftime
+        if cf_units.__version__ > '1':
+            import cftime
+            expected_index = [cftime.Datetime360Day(2000, 1, 1, 0, 0),
+                              cftime.Datetime360Day(2000, 4, 11, 2, 24),
+                              cftime.Datetime360Day(2000, 7, 21, 4, 48),
+                              cftime.Datetime360Day(2000, 11, 1, 7, 12),
+                              cftime.Datetime360Day(2001, 2, 11, 9, 36)]
+
+        else:
             expected_index = [netcdftime.Datetime360Day(2000, 1, 1, 0, 0),
                               netcdftime.Datetime360Day(2000, 4, 11, 2, 24),
                               netcdftime.Datetime360Day(2000, 7, 21, 4, 48),
                               netcdftime.Datetime360Day(2000, 11, 1, 7, 12),
                               netcdftime.Datetime360Day(2001, 2, 11, 9, 36)]
-        else:
-            expected_index = [netcdftime.datetime(2000, 1, 1, 0, 0),
-                              netcdftime.datetime(2000, 4, 11, 2, 24),
-                              netcdftime.datetime(2000, 7, 21, 4, 48),
-                              netcdftime.datetime(2000, 11, 1, 7, 12),
-                              netcdftime.datetime(2001, 2, 11, 9, 36)]
+
         series = iris.pandas.as_series(cube)
         self.assertArrayEqual(series, cube.data)
         self.assertArrayEqual(series.index, expected_index)
@@ -244,12 +248,16 @@ def test_time_360(self):
         time_coord = DimCoord([100.1, 200.2], long_name="time",
                               units=time_unit)
         cube.add_dim_coord(time_coord, 0)
-        if netCDF4.__version__ > '1.2.4':
+        # TODO: Remove this if statement once we move to exclusive cftime.
+        if cf_units.__version__ > '1':
+            # cf_units depends upon cftime, so we can safely assume we
+            # have it.
+            import cftime
+            expected_index = [cftime.Datetime360Day(2000, 4, 11, 2, 24),
+                              cftime.Datetime360Day(2000, 7, 21, 4, 48)]
+        else:
             expected_index = [netcdftime.Datetime360Day(2000, 4, 11, 2, 24),
                               netcdftime.Datetime360Day(2000, 7, 21, 4, 48)]
-        else:
-            expected_index = [netcdftime.datetime(2000, 4, 11, 2, 24),
-                              netcdftime.datetime(2000, 7, 21, 4, 48)]
         expected_columns = [0, 1, 2, 3, 4]
         data_frame = iris.pandas.as_data_frame(cube)
         self.assertArrayEqual(data_frame, cube.data)

setup.cfg

@@ -42,7 +42,6 @@ exclude = */iris/std_names.py,\
           */iris/tests/test_pp_to_cube.py,\
           */iris/tests/test_quickplot.py,\
           */iris/tests/test_std_names.py,\
-          */iris/tests/test_unit.py,\
           */iris/tests/test_uri_callback.py,\
           */iris/tests/test_util.py