https://github.com/neithere/argh/issues/239

--- argh-0.31.3/tests/base.py.orig
+++ argh-0.31.3/tests/base.py
@@ -4,8 +4,6 @@
 """
 
 import io
-import os
-import sys
 from collections import namedtuple
 
 from argh import ArghParser
@@ -72,8 +70,3 @@
             raise AssertionError("Did not exit")
         return result.exit_code
     return result
-
-
-def get_usage_string(definitions="{cmd} ..."):
-    prog = os.path.basename(sys.argv[0])
-    return "usage: " + prog + " [-h] " + definitions + "\n\n"
--- argh-0.31.3/tests/test_integration.py.orig
+++ argh-0.31.3/tests/test_integration.py
@@ -17,7 +17,7 @@
 from argh.utils import unindent
 
 from .base import CmdResult as R
-from .base import DebugArghParser, get_usage_string, run
+from .base import DebugArghParser, run
 
 if sys.version_info < (3, 10):
     HELP_OPTIONS_LABEL = "optional arguments"
@@ -796,11 +796,17 @@
     parser = DebugArghParser()
     parser.set_default_command(func)
 
-    assert unindent(func.__doc__) in parser.format_help()
+    docstring = func.__doc__
+    assert docstring
+    assert unindent(docstring) in parser.format_help()
 
 
 def test_prog(capsys: pytest.CaptureFixture[str]):
-    "Program name propagates from sys.argv[0]"
+    """
+    Program name propagates to the usage string.
+    It's not just sys.argv[0], the logic is a bit more complicated in argparse,
+    so we just reuse whatever it has produced.
+    """
 
     def cmd(*, foo=1):
         return foo
@@ -808,10 +814,12 @@
     parser = DebugArghParser()
     parser.add_commands([cmd])
 
-    usage = get_usage_string()
+    usage = f"usage: {parser.prog} [-h]"
 
-    assert run(parser, "-h", exit=True) == 0
+    exit_code = run(parser, "-h", exit=True)
     captured = capsys.readouterr()
+
+    assert exit_code == 0
     assert captured.out.startswith(usage)
 
 
@@ -822,8 +830,6 @@
     parser = DebugArghParser()
     parser.set_default_command(cmd)
 
-    get_usage_string("[-f FOO]")
-
     assert run(parser, "--foo 1") == R(out="1\n", err="")
     assert run(parser, "--bar 1", exit=True) == "unrecognized arguments: --bar 1"
     assert run(parser, "--bar 1", exit=False, kwargs={"skip_unknown_args": True}) == R(