If both add_offset and scale_factor are specified for a var, check if…

… same type

compliance_checker/cf/cf_1_6.py

@@ -170,6 +170,18 @@ def check_add_offset_scale_factor_type(self, ds):
             scale_factor=lambda x: x is not None
         )
 
+        _attr_vars_tup = []
+        both = set(add_offset_vars).intersection(scale_factor_vars)
+        both_msgs = []
+        for both_var in sorted(both, key=lambda var: var.name):
+            if (both_var.scale_factor.dtype !=
+                both_var.add_offset.dtype):
+                both_msgs.append("When both scale_factor and add_offset "
+                                 f"are supplied for variable {both_var.name}, "
+                                 "they must have the same type")
+        results.append(Result(BaseCheck.MEDIUM, not bool(both_msgs),
+                       self.section_titles["8.1"], both_msgs))
+
         for _att_vars_tup in (
             ("add_offset", add_offset_vars),
             ("scale_factor", scale_factor_vars),

compliance_checker/tests/test_cf.py

@@ -2215,45 +2215,45 @@ def test_check_add_offset_scale_factor_type(self):
         # set att bad (str)
         temp.setncattr("add_offset", "foo")
         r = self.cf.check_add_offset_scale_factor_type(dataset)
-        self.assertFalse(r[0].value)
+        self.assertFalse(r[1].value)
         # messages should be non-empty for improper type
-        self.assertTrue(r[0].msgs)
+        self.assertTrue(r[1].msgs)
         del temp.add_offset
 
         temp.setncattr("scale_factor", "foo")
         r = self.cf.check_add_offset_scale_factor_type(dataset)
-        self.assertFalse(r[0].value)
-        self.assertTrue(r[0].msgs)
+        self.assertFalse(r[1].value)
+        self.assertTrue(r[1].msgs)
 
         # set bad np val
         temp.setncattr("scale_factor", np.float32(5))
         r = self.cf.check_add_offset_scale_factor_type(dataset)
-        self.assertFalse(r[0].value)
-        self.assertTrue(r[0].msgs)
+        self.assertFalse(r[1].value)
+        self.assertTrue(r[1].msgs)
 
         temp.setncattr("scale_factor", np.uint(5))
         r = self.cf.check_add_offset_scale_factor_type(dataset)
-        self.assertFalse(r[0].value)
-        self.assertTrue(r[0].msgs)
+        self.assertFalse(r[1].value)
+        self.assertTrue(r[1].msgs)
 
         # set good
         temp.setncattr("scale_factor", np.float(5))
         r = self.cf.check_add_offset_scale_factor_type(dataset)
-        self.assertTrue(r[0].value)
-        self.assertFalse(r[0].msgs)
+        self.assertTrue(r[1].value)
+        self.assertFalse(r[1].msgs)
 
         temp.setncattr("scale_factor", np.double(5))
         r = self.cf.check_add_offset_scale_factor_type(dataset)
-        self.assertTrue(r[0].value)
-        self.assertFalse(r[0].msgs)
+        self.assertTrue(r[1].value)
+        self.assertFalse(r[1].msgs)
 
         # set same dtype
         dataset = MockTimeSeries()  # time lat lon depth
         temp = dataset.createVariable("temp", np.int, dimensions=("time",))
         temp.setncattr("scale_factor", np.int(5))
         r = self.cf.check_add_offset_scale_factor_type(dataset)
-        self.assertTrue(r[0].value)
-        self.assertFalse(r[0].msgs)
+        self.assertTrue(r[1].value)
+        self.assertFalse(r[1].msgs)
 
         # integer variable type (int8, int16, int32) compared against
         #floating point add_offset/scale_factor
@@ -2264,8 +2264,18 @@ def test_check_add_offset_scale_factor_type(self):
             coarse_temp.setncattr("scale_factor", np.float32(23.0))
             coarse_temp.setncattr("add_offset", np.double(-2.1))
             r = self.cf.check_add_offset_scale_factor_type(dataset)
-            self.assertTrue(r[0].value)
-            self.assertFalse(r[0].msgs)
+            # First value which checks if add_offset and scale_factor
+            # are same type should be false
+            self.assertFalse(r[0].value)
+            self.assertEqual(r[0].msgs[0],
+                   "When both scale_factor and add_offset are supplied for "
+                   f"variable coarse_temp_{var_bytes}, they must have the "
+                   "same type")
+            # Individual checks for scale_factor/add_offset should be OK,
+            # however
+            self.assertTrue(r[-1].value)
+            self.assertFalse(r[-1].msgs)
+            del dataset.variables[f"coarse_temp_{var_bytes}"]
 
 
 class TestCF1_8(BaseTestCase):