Added support for typing.IO, TextIO, BinaryIO

runtype/pytypes.py

@@ -2,6 +2,7 @@
 Python Types - contains an implementation of a Runtype type system that is parallel to the Python type system.
 """
 
+import io
 import typing as t
 import contextvars
 import types
@@ -565,6 +566,12 @@ def _to_canon(self, t):
             return MutableSequence
         elif t is typing.Callable:
             return Callable
+        elif t is typing.IO:
+            return PythonDataType(io.IOBase)
+        elif t is typing.TextIO:
+            return PythonDataType(io.TextIOBase)
+        elif t is typing.BinaryIO:
+            return PythonDataType(io.BytesIO)
 
         if origin is None:
             if isinstance(t, typing.TypeVar):

tests/test_types.py

@@ -3,6 +3,7 @@
 from unittest import TestCase
 import typing
 import collections.abc as cabc
+import io
 
 from runtype.base_types import DataType, GenericType, PhantomType, Variance
 from runtype.pytypes import type_caster, List, Dict, Int, Any, Constraint, String, Tuple, Iter, Literal, NoneType, Sequence, Mapping    
@@ -295,6 +296,20 @@ class _Str(str):
         assert make_type(typing.Callable[[str, int], _Str]) <= repeat
         assert repeat <= make_type(typing.Callable[[_Str, int], str])
 
+    def test_io(self):
+        IO = make_type(io.IOBase)
+        TextIO = make_type(io.TextIOBase)
+        assert IO <= IO
+        assert TextIO <= IO
+        assert IO.test_instance(sys.stdout)
+
+    def test_typing_io(self):
+        IO = make_type(typing.IO)
+        TextIO = make_type(typing.TextIO)
+        assert IO <= IO
+        assert TextIO <= IO
+        assert IO.test_instance(sys.stdout)
+
 
 
 if __name__ == '__main__':