Test both unify and reifying nonstandard objects

Change from the previous commit only affects reifying nonstandard
objects, so this change better reflects the new situation.
Use the base `unify` and `reify` functions to test instead of the
private functions.

tests/test_more.py

@@ -1,4 +1,4 @@
-from ast import Num
+import ast
 from collections.abc import Mapping
 
 from unification import var
@@ -31,10 +31,11 @@ def test_unify_object():
 
 
 def test_unify_nonstandard_object():
+    _unify.add((ast.AST, ast.AST, Mapping), _unify_object)
     x = var()
-    assert stream_eval(_unify_object(Num(n=1), Num(n=1), {})) == {}
-    assert stream_eval(_unify_object(Num(n=1), Num(n=2), {})) is False
-    assert stream_eval(_unify_object(Num(n=1), Num(n=x), {})) == {x: 1}
+    assert unify(ast.Num(n=1), ast.Num(n=1), {}) == {}
+    assert unify(ast.Num(n=1), ast.Num(n=2), {}) is False
+    assert unify(ast.Num(n=1), ast.Num(n=x), {}) == {x: 1}
 
 
 def test_reify_object():
@@ -47,6 +48,14 @@ def test_reify_object():
     assert stream_eval(_reify_object(f, {})) is f
 
 
+def test_reify_nonstandard_object():
+    _reify.add((ast.AST, Mapping), _reify_object)
+    x = var()
+    assert reify(ast.Num(n=1), {}).n == 1
+    assert reify(ast.Num(n=x), {}).n == x
+    assert reify(ast.Num(n=x), {x: 2}).n == 2
+
+
 def test_reify_slots():
     class SlotsObject(object):
         __slots__ = ["myattr"]