Fix FloatRationalizer() for CPython 3.9

diofant/interactive/session.py

@@ -69,12 +69,13 @@ def visit_Name(self, node):
 class FloatRationalizer(ast.NodeTransformer):
     """Wraps all floats in a call to Rational."""
 
-    def visit_Num(self, node):
+    def visit_Constant(self, node):
         if isinstance(node.n, float):
             return ast.Call(func=ast.Name(id='Rational', ctx=ast.Load()),
                             args=[ast.Str(s=repr(node.n))], keywords=[],
                             starargs=None, kwargs=None)
         return node
+    visit_Num = visit_Constant
 
     def visit_Call(self, node):
         if isinstance(node.func, ast.Name) and node.func.id == 'Float':

diofant/tests/interactive/test_ipythonprinting.py

@@ -1,7 +1,5 @@
 """Tests that the IPython printing module is properly loaded."""
 
-import sys
-
 import pytest
 
 from diofant.core import Float, Rational, Symbol
@@ -12,7 +10,6 @@
 ipython = pytest.importorskip('IPython', minversion='2.3.0')
 
 
-@pytest.mark.skipif(sys.version_info >= (3, 8), reason='Broken on 3.8')
 def test_ipython_printing(monkeypatch):
     app = ipython.terminal.ipapp.TerminalIPythonApp()
     app.display_banner = False