Fix interface compatibility check for null types when subsets are all…

…owed.

neurokernel/pattern.py

@@ -621,10 +621,12 @@ def is_compatible(self, a, i, b, allow_subsets=False):
             if not len(data_merged):
                 return False
 
-            # Compatible identifiers must have the same 'type' attribute
-            # and their 'io' attributes must be the inverse of each other;:
+            # Compatible identifiers must have the same non-null 'type'
+            # attribute and their 'io' attributes must be the inverse of each
+            # other:
             if not data_merged.apply(lambda row: \
-                    (row['type_x'] == row['type_y']) and \
+                    ((row['type_x'] == row['type_y']) or \
+                     (pd.isnull(row['type_x']) and pd.isnull(row['type_y']))) and \
                     ((row['io_x'] == 'out' and row['io_y'] == 'in') or \
                      (row['io_x'] == 'in' and row['io_y'] == 'out')),
                                      axis=1).any():
@@ -640,7 +642,7 @@ def is_compatible(self, a, i, b, allow_subsets=False):
                 return False
 
             # If the 'type' attributes of the same identifiers in each
-            # interfaces are not equivalent, they are incompatible:
+            # interfaces are not equivalent or both null, they are incompatible:
             if not data_merged.apply(lambda row: \
                     (row['type_x'] == row['type_y']) or \
                     (pd.isnull(row['type_x']) and pd.isnull(row['type_y'])),

tests/test_pattern.py

@@ -469,7 +469,8 @@ def test_is_compatible_with_nulls_types(self):
     def test_is_compatible_subsets(self):
         """
         Interfaces that both share a subset of compatible ports can be deemed
-        compatible by setting the `allow_subsets` option of the compatibility test.
+        compatible by setting the `allow_subsets` option of the compatibility
+        test.
         """
 
         i = Interface('/foo[0:6]')
@@ -482,6 +483,23 @@ def test_is_compatible_subsets(self):
         assert i.is_compatible(0, j, 1, True)
         assert i.is_compatible(0, k, 1, True) == False
 
+    def test_is_compatible_subsets_with_null_types(self):
+        """
+        Interfaces that both share a subset of compatible ports can be deemed
+        compatible by setting the `allow_subsets` option of the compatibility
+        test even when the types are null.
+        """
+
+        i = Interface('/foo[0:6]')
+        i['/foo[0:3]'] = [0, 'out']
+        i['/foo[3:6]'] = [0, 'out']
+        j = Interface('/foo[0:6]')
+        j['/foo[0:2]'] = [1, 'in']
+        j['/foo[3:5]'] = [1, 'in']
+        k = Interface('/foo[0:6]')
+        assert i.is_compatible(0, j, 1, True)
+        assert i.is_compatible(0, k, 1, True) == False
+
     def test_which_int_unset(self):
         i = Interface('/foo[0:4]')
         assert i.which_int('/foo[0:2]') == set()