asyncio: subprocess_shell() and subprocess_exec() now raise ValueError instead of assert.

Moreover, bufsize different than 0 is now considered as an error.

Lib/asyncio/base_events.py

@@ -552,9 +552,14 @@ class BaseEventLoop(events.AbstractEventLoop):
                          stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                          universal_newlines=False, shell=True, bufsize=0,
                          **kwargs):
-        assert not universal_newlines, "universal_newlines must be False"
+        if not isinstance(cmd, str):
-        assert shell, "shell must be True"
+            raise ValueError("cmd must be a string")
-        assert isinstance(cmd, str), cmd
+        if universal_newlines:
+            raise ValueError("universal_newlines must be False")
+        if not shell:
+            raise ValueError("shell must be False")
+        if bufsize != 0:
+            raise ValueError("bufsize must be 0")
         protocol = protocol_factory()
         transport = yield from self._make_subprocess_transport(
             protocol, cmd, True, stdin, stdout, stderr, bufsize, **kwargs)
@@ -565,8 +570,12 @@ class BaseEventLoop(events.AbstractEventLoop):
                         stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                         universal_newlines=False, shell=False, bufsize=0,
                         **kwargs):
-        assert not universal_newlines, "universal_newlines must be False"
+        if universal_newlines:
-        assert not shell, "shell must be False"
+            raise ValueError("universal_newlines must be False")
+        if shell:
+            raise ValueError("shell must be False")
+        if bufsize != 0:
+            raise ValueError("bufsize must be 0")
         protocol = protocol_factory()
         transport = yield from self._make_subprocess_transport(
             protocol, args, False, stdin, stdout, stderr, bufsize, **kwargs)

Lib/test/test_asyncio/test_events.py

@@ -1491,6 +1491,38 @@ class SubprocessTestsMixin:
         self.loop.run_until_complete(proto.completed)
         self.assertEqual(7, proto.returncode)
 
+    def test_subprocess_exec_invalid_args(self):
+        @asyncio.coroutine
+        def connect(**kwds):
+            yield from self.loop.subprocess_exec(
+                asyncio.SubprocessProtocol,
+                'pwd', **kwds)
+
+        with self.assertRaises(ValueError):
+            self.loop.run_until_complete(connect(universal_newlines=True))
+        with self.assertRaises(ValueError):
+            self.loop.run_until_complete(connect(bufsize=4096))
+        with self.assertRaises(ValueError):
+            self.loop.run_until_complete(connect(shell=True))
+
+    def test_subprocess_shell_invalid_args(self):
+        @asyncio.coroutine
+        def connect(cmd=None, **kwds):
+            if not cmd:
+                cmd = 'pwd'
+            yield from self.loop.subprocess_shell(
+                asyncio.SubprocessProtocol,
+                cmd, **kwds)
+
+        with self.assertRaises(ValueError):
+            self.loop.run_until_complete(connect(['ls', '-l']))
+        with self.assertRaises(ValueError):
+            self.loop.run_until_complete(connect(universal_newlines=True))
+        with self.assertRaises(ValueError):
+            self.loop.run_until_complete(connect(bufsize=4096))
+        with self.assertRaises(ValueError):
+            self.loop.run_until_complete(connect(shell=False))
+
 
 if sys.platform == 'win32':