tests: Update caching test and fix minor decomposition bug

devito/data/decomposition.py

@@ -320,7 +320,7 @@ def index_glb_to_loc(self, *args, rel=True):
             if self.loc_empty:
                 return None
             abs_ofs, side = args
-            if side is LEFT:
+            if side == LEFT:
                 rel_ofs = self.glb_min + abs_ofs - base
                 if abs_ofs >= base and abs_ofs <= top:
                     return rel_ofs

tests/test_caching.py

@@ -694,6 +694,11 @@ def test_sparse_function(self, operate_on_empty_cache):
         # Now we should be back to the original state plus the dimension bounds
         # (x_m, x_M, y_m, y_M)
         assert len(_SymbolCache) == init_cache_size + 4
+        # Delete the grid and check that all symbols are subsequently garbage collected
+        del grid
+        for n in (10, 3, 0):
+            clear_cache()
+            assert len(_SymbolCache) == n
 
     def test_after_indexification(self):
         """