Avoid stale cache for multimodel statistics regression tests (#1030)

Author: bouweandela

tests/sample_data/multimodel_statistics/test_multimodel.py

@@ -14,6 +14,9 @@
 
 esmvaltool_sample_data = pytest.importorskip("esmvaltool_sample_data")
 
+# Increase this number anytime you change the cached input data to the tests.
+TEST_REVISION = 1
+
 CALENDAR_PARAMS = (
     pytest.param(
         '360_day',
@@ -41,6 +44,7 @@ def assert_array_almost_equal(this, other):
 
 def preprocess_data(cubes, time_slice: dict = None):
     """Regrid the data to the first cube and optional time-slicing."""
+    # Increase TEST_REVISION anytime you make changes to this function.
     if time_slice:
         cubes = [extract_time(cube, **time_slice) for cube in cubes]
 
@@ -61,14 +65,14 @@ def get_cache_key(value):
     """Get a cache key that is hopefully unique enough for unpickling.
 
     If this doesn't avoid problems with unpickling the cached data,
-    manually clean the pytest cache with the command `pytest --cache-
-    clear`.
+    manually clean the pytest cache with the command `pytest --cache-clear`.
     """
     return ' '.join([
         str(value),
         iris.__version__,
         np.__version__,
         sys.version,
+        f"rev-{TEST_REVISION}",
     ])
 
 
@@ -82,6 +86,7 @@ def timeseries_cubes_month(request):
     if data:
         cubes = pickle.loads(data.encode('latin1'))
     else:
+        # Increase TEST_REVISION anytime you make changes here.
         time_slice = {
             'start_year': 1985,
             'end_year': 1987,
@@ -111,6 +116,7 @@ def timeseries_cubes_day(request):
         cubes = pickle.loads(data.encode('latin1'))
 
     else:
+        # Increase TEST_REVISION anytime you make changes here.
         time_slice = {
             'start_year': 2001,
             'end_year': 2002,