From 3445eae737e5d5110674ad5aff1f87263c1be089 Mon Sep 17 00:00:00 2001
From: Daniel Hahler <git@thequod.de>
Date: Tue, 11 Dec 2018 04:54:54 +0100
Subject: [PATCH] argparsing: Parser: allow to forward prog to argparse

Ref: https://github.com/pytest-dev/pytest-xdist/pull/388.
---
 src/_pytest/config/argparsing.py | 7 +++++--
 testing/test_parseopt.py         | 6 ++++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/_pytest/config/argparsing.py b/src/_pytest/config/argparsing.py
index 5b8306dda..51f708335 100644
--- a/src/_pytest/config/argparsing.py
+++ b/src/_pytest/config/argparsing.py
@@ -18,6 +18,8 @@ class Parser(object):
         there's an error processing the command line arguments.
     """
 
+    prog = None
+
     def __init__(self, usage=None, processopt=None):
         self._anonymous = OptionGroup("custom options", parser=self)
         self._groups = []
@@ -82,7 +84,7 @@ class Parser(object):
     def _getparser(self):
         from _pytest._argcomplete import filescompleter
 
-        optparser = MyOptionParser(self, self.extra_info)
+        optparser = MyOptionParser(self, self.extra_info, prog=self.prog)
         groups = self._groups + [self._anonymous]
         for group in groups:
             if group.options:
@@ -319,12 +321,13 @@ class OptionGroup(object):
 
 
 class MyOptionParser(argparse.ArgumentParser):
-    def __init__(self, parser, extra_info=None):
+    def __init__(self, parser, extra_info=None, prog=None):
         if not extra_info:
             extra_info = {}
         self._parser = parser
         argparse.ArgumentParser.__init__(
             self,
+            prog=prog,
             usage=parser._usage,
             add_help=False,
             formatter_class=DropShorterLongHelpFormatter,
diff --git a/testing/test_parseopt.py b/testing/test_parseopt.py
index 3048c96bd..c3b4ee698 100644
--- a/testing/test_parseopt.py
+++ b/testing/test_parseopt.py
@@ -24,6 +24,12 @@ class TestParser(object):
         out, err = capsys.readouterr()
         assert err.find("error: unrecognized arguments") != -1
 
+    def test_custom_prog(self, parser):
+        """Custom prog can be set for `argparse.ArgumentParser`."""
+        assert parser._getparser().prog == os.path.basename(sys.argv[0])
+        parser.prog = "custom-prog"
+        assert parser._getparser().prog == "custom-prog"
+
     def test_argument(self):
         with pytest.raises(parseopt.ArgumentError):
             # need a short or long option