Allow stdin=subprocess.DEVNULL

The current default is to connect through the existing stdin to the
subprocess, and there is no way to explicitly close the subprocess
stdin. Allow stdin=subprocess.DEVNULL for this.

(Backport from v3.0)

Author: Anthchirp

HISTORY.rst

@@ -2,6 +2,11 @@
 History
 =======
 
+2.3.2 (2022-01-28)
+------------------
+* The run() function now understands stdin=subprocess.DEVNULL to close the subprocess stdin,
+  rather than to connect through the existing stdin, which is the current default
+
 2.3.1 (2021-10-25)
 ------------------
 * Add Python 3.10 support

procrunner/__init__.py

@@ -455,7 +455,8 @@ def run(
     :param array command: Command line to be run, specified as array.
     :param timeout: Terminate program execution after this many seconds.
     :param boolean debug: Enable further debug messages. (deprecated)
-    :param stdin: Optional bytestring that is passed to command stdin.
+    :param stdin: Optional bytestring that is passed to command stdin,
+                  or subprocess.DEVNULL to disable stdin.
     :param boolean print_stdout: Pass stdout through to sys.stdout.
     :param boolean print_stderr: Pass stderr through to sys.stderr.
     :param callback_stdout: Optional function which is called for each
@@ -485,6 +486,12 @@ def run(
 
     if stdin is None:
         stdin_pipe = None
+    elif isinstance(stdin, int):
+        assert (
+            stdin == subprocess.DEVNULL
+        ), "stdin argument only allows subprocess.DEVNULL as numeric argument"
+        stdin_pipe = subprocess.DEVNULL
+        stdin = None
     else:
         assert sys.platform != "win32", "stdin argument not supported on Windows"
         stdin_pipe = subprocess.PIPE

tests/test_procrunner_system.py

@@ -21,6 +21,19 @@ def test_simple_command_invocation():
     assert result.stderr == b""
 
 
+def test_simple_command_invocation_with_closed_stdin():
+    if os.name == "nt":
+        command = ["cmd.exe", "/c", "echo", "hello"]
+    else:
+        command = ["echo", "hello"]
+
+    result = procrunner.run(command, stdin=subprocess.DEVNULL)
+
+    assert result.returncode == 0
+    assert result.stdout == b"hello" + os.linesep.encode("utf-8")
+    assert result.stderr == b""
+
+
 def test_decode_invalid_utf8_input(capsys):
     test_string = b"test\xa0string\n"
     if os.name == "nt":