Fix over-eager fallback to stdin

.gitignore

@@ -16,6 +16,7 @@ develop-eggs/
 dist/
 downloads/
 eggs/
+.eggs/
 lib/
 lib64/
 parts/

jwt/__main__.py

@@ -54,10 +54,13 @@ def encode_payload(args):
 
 def decode_payload(args):
     try:
-        if sys.stdin.isatty():
-            token = sys.stdin.read()
-        else:
+        if args.token:
             token = args.token
+        else:
+            if sys.stdin.isatty():
+                token = sys.stdin.readline().strip()
+            else:
+                raise IOError('Cannot read from stdin: terminal not a TTY')
 
         token = token.encode('utf-8')
         data = decode(token, key=args.key, verify=args.verify)
@@ -133,7 +136,10 @@ def build_argparser():
 
     # Decode subcommand
     decode_parser = subparsers.add_parser('decode', help='use to decode a supplied JSON web token')
-    decode_parser.add_argument('token', help='JSON web token to decode.')
+    decode_parser.add_argument(
+        'token',
+        help='JSON web token to decode.',
+        nargs='?')
 
     decode_parser.add_argument(
         '-n', '--no-verify',

tests/test_cli.py

@@ -57,6 +57,37 @@ def patched_sys_stdin_read():
 
         assert 'There was an error decoding the token' in str(excinfo.value)
 
+    def test_decode_payload_terminal_tty(self, monkeypatch):
+        encode_args = [
+            '--key=secret-key',
+            'encode',
+            'name=hello-world',
+        ]
+        parser = build_argparser()
+        parsed_encode_args = parser.parse_args(encode_args)
+        token = encode_payload(parsed_encode_args)
+
+        decode_args = ['--key=secret-key', 'decode']
+        parsed_decode_args = parser.parse_args(decode_args)
+
+        monkeypatch.setattr(sys.stdin, 'isatty', lambda: True)
+        monkeypatch.setattr(sys.stdin, 'readline', lambda:  token)
+
+        actual = json.loads(decode_payload(parsed_decode_args))
+        assert actual['name'] == 'hello-world'
+
+    def test_decode_payload_raises_terminal_not_a_tty(self, monkeypatch):
+        decode_args = ['--key', '1234', 'decode']
+        parser = build_argparser()
+        args = parser.parse_args(decode_args)
+
+        monkeypatch.setattr(sys.stdin, 'isatty', lambda: False)
+
+        with pytest.raises(IOError) as excinfo:
+            decode_payload(args)
+            assert 'Cannot read from stdin: terminal not a TTY' \
+                in str(excinfo.value)
+
     @pytest.mark.parametrize('key,name,job,exp,verify', [
         ('1234', 'Vader', 'Sith', None, None),
         ('4567', 'Anakin', 'Jedi', '+1', None),