#2683: Popen.communicate() argument must be bytes.

Lib/subprocess.py

@@ -883,8 +883,6 @@ class Popen(object):
 
             if self.stdin:
                 if input is not None:
-                    if isinstance(input, str):
-                        input = input.encode()
                     self.stdin.write(input)
                 self.stdin.close()
 
@@ -1129,10 +1127,6 @@ class Popen(object):
 
 
         def _communicate(self, input):
-            if self.stdin:
-                if isinstance(input, str): # Unicode
-                    input = input.encode("utf-8") # XXX What else?
-                input = bytes(input)
             read_set = []
             write_set = []
             stdout = None # Return

Lib/test/test_subprocess.py

@@ -302,7 +302,7 @@ class ProcessTestCase(unittest.TestCase):
                              stdin=subprocess.PIPE,
                              stdout=subprocess.PIPE,
                              stderr=subprocess.PIPE)
-        (stdout, stderr) = p.communicate("banana")
+        (stdout, stderr) = p.communicate(b"banana")
         self.assertEqual(stdout, b"banana")
         self.assertEqual(remove_stderr_debug_decorations(stderr),
                          b"pineapple")
@@ -420,7 +420,7 @@ class ProcessTestCase(unittest.TestCase):
                                  stdin=subprocess.PIPE,
                                  stdout=subprocess.PIPE,
                                  stderr=subprocess.PIPE)
-            data = p.communicate("lime")[0]
+            data = p.communicate(b"lime")[0]
             self.assertEqual(data, b"lime")
 
 

Misc/NEWS

@@ -17,6 +17,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #2683: Fix inconsistency in subprocess.Popen.communicate(): the
+  argument now must be a bytes object in any case.
+
 - Issue #3145: help("modules whatever") failed when trying to load the source
   code of every single module of the standard library, including invalid files
   used in the test suite.