improve error messages

lbry/service/parser.py

@@ -159,7 +159,9 @@ def parse_method(method, expanders: dict) -> dict:
                     raise Exception(f"Expander '{expander_name}' not found, used by {d['name']}.")
                 for expanded in expanders[expander_name]:
                     if expanded['name'] in known_names:
-                        raise Exception(f"Expander '{expander_name}' argument repeated: {expanded['name']}.")
+                        raise Exception(
+                            f"Expander '{expander_name}' argument repeated '{expanded['name']}' used by {d['name']}."
+                        )
                     d['arguments'].append(expanded)
                     d['kwargs'].append(expanded)
                     known_names.add(expanded['name'])
@@ -213,11 +215,12 @@ def generate_options(method, indent) -> List[str]:
         if 'default' in arg:
             if arg['type'] != 'bool':
                 text += f" [default: {arg['default']}]"
-        wrapped = textwrap.wrap(text, LINE_WIDTH-len(left))
+        wrapped = textwrap.wrap(text, LINE_WIDTH-len(left), break_long_words=False)
         lines = [f"{left}{wrapped.pop(0)}"]
         # dont break on -- or docopt will parse as a new option
         for line in wrapped:
             if line.strip().startswith('--'):
+                print(f"Full text before continuation error: \"{text}\"")
                 raise Exception(f"Continuation line starts with -- on {method['cli']}: \"{line.strip()}\"")
             lines.append(f"{' ' * len(left)} {line}")
         options.extend(lines)

tests/unit/service/test_parser.py

@@ -97,7 +97,10 @@ class TestParser(TestCase):
     def test_parse_does_not_allow_duplicate_arguments(self):
         with self.assertRaises(Exception) as exc:
             parse_method(BadAPI.thing_search, get_expanders())
-        self.assertEqual(exc.exception.args[0], "Expander 'another_test' argument repeated: somevalue.")
+        self.assertEqual(
+            exc.exception.args[0],
+            "Expander 'another_test' argument repeated 'somevalue' used by thing_search."
+        )
 
     def test_parse_does_not_allow_line_break_with_two_dashes(self):
         # breaking with two dashes breaks docopt parsing