bpo-35246: fix support for path-like args in asyncio subprocess

drop isinstance checks from create_subprocess_exec function and let
subprocess module do them.

Lib/asyncio/base_events.py

@@ -1605,11 +1605,6 @@ async def subprocess_exec(self, protocol_factory, program, *args,
             raise ValueError("errors must be None")
 
         popen_args = (program,) + args
-        for arg in popen_args:
-            if not isinstance(arg, (str, bytes)):
-                raise TypeError(
-                    f"program arguments must be a bytes or text string, "
-                    f"not {type(arg).__name__}")
         protocol = protocol_factory()
         debug_log = None
         if self._debug:

Lib/test/test_asyncio/test_subprocess.py

@@ -622,6 +622,18 @@ async def execute():
         self.loop.run_until_complete(execute())
 
 
+    def test_create_subprocess_exec_with_path(self):
+        async def execute():
+            from pathlib import Path
+            p = await subprocess.create_subprocess_exec(
+                Path(sys.executable), '-c', 'pass')
+            await p.wait()
+            p = await subprocess.create_subprocess_exec(
+                sys.executable, '-c', 'pass', Path('.'))
+            await p.wait()
+
+        self.loop.run_until_complete(execute())
+
 if sys.platform != 'win32':
     # Unix
     class SubprocessWatcherMixin(SubprocessMixin):

Misc/NEWS.d/next/Library/2019-05-28-23-17-35.bpo-35246.oXT21d.rst

@@ -0,0 +1 @@
+Make :func:`asyncio.create_subprocess_exec` accept path-like arguments.