More small tidyups

- switch to using sys.exit instead of exit
 - always exit with error-code 1
 - don't bother testing error-codes
 - documentation wording tweak

docs/cli_tools.rst

@@ -7,7 +7,7 @@ Pinout
 
 The gpiozero package contains a database of information about the various
 revisions of Raspberry Pi. This is queried by the ``pinout`` command-line
-tool to write details of the GPIO pins available.
+tool to output details of the GPIO pins available.
 
 Unless specified, the revision of the current device will be detected. A
 particular revision may be selected with the --revision command-line

gpiozero/cli/pinout.py

@@ -45,7 +45,7 @@ def parse_args(args):
     except argparse.ArgumentError as ex:
         print('Error parsing arguments.')
         parser.error(str(ex.message))
-        exit(-1)
+        sys.exit(1)
     return args
 
 
@@ -57,7 +57,7 @@ def main():
             pi_info().pprint(color=args.color)
         except IOError:
             print('This device is not a Raspberry Pi')
-            exit(2)
+            sys.exit(1)
     else:
         pi_info(args.revision).pprint(color=args.color)
 

tests/cli/test_pinout.py

@@ -15,8 +15,6 @@ from gpiozero.cli import pinout
 def test_args_incorrect():
     with pytest.raises(SystemExit) as ex:
         pinout.parse_args(['--nonexistentarg'])
-    assert ex.value.code == 2
-
 
 def test_args_color():
     args = pinout.parse_args([])
@@ -26,15 +24,12 @@ def test_args_color():
     args = pinout.parse_args(['--monochrome'])
     assert args.color is False
 
-
 def test_args_revision():
     args = pinout.parse_args(['--revision', '000d'])
     assert args.revision == '000d'
 
-
 def test_help(capsys):
     with pytest.raises(SystemExit) as ex:
         pinout.parse_args(['--help'])
     out, err = capsys.readouterr()
     assert 'GPIO pinout' in out
-    assert ex.value.code == 0