handle properly even json requirement was multiple lines (#199)

lockable/lockable.py

@@ -84,12 +84,12 @@ def parse_requirements(requirements_str: (str or dict)) -> dict:
             return {}
         if isinstance(requirements_str, dict):
             return requirements_str
-        try:
-            return json.loads(requirements_str)
-        except json.decoder.JSONDecodeError as error:
-            # if the first char is not {, try to parse as string requirements
-            if error.colno > 1:
-                # expecting requirements_str to be a json format
+        assert isinstance(requirements_str, str), 'requirements must be string or dict'
+        requirements_str = requirements_str.strip()  # remove leading and trailing spaces
+        if requirements_str.startswith('{'):
+            try:
+                return json.loads(requirements_str)
+            except json.decoder.JSONDecodeError as error:
                 raise ValueError(str(error)) from error
         return Lockable.parse_str_requirements(requirements_str)
 

tests/test_Lockable.py

@@ -125,12 +125,18 @@ def test_parse_requirements(self):
         self.assertEqual(Lockable.parse_requirements('a=False'), {"a": False})
         self.assertEqual(Lockable.parse_requirements('a=b&c=d'), {"a": "b", "c": "d"})
         self.assertEqual(Lockable.parse_requirements('{"a":"b","c":"d"}'), {"a": "b", "c": "d"})
+        with self.assertRaises(ValueError):
+            Lockable.parse_requirements('{')
+        with self.assertRaises(AssertionError):
+            Lockable.parse_requirements(1)
         with self.assertRaises(ValueError):
             Lockable.parse_requirements('a')
         with self.assertRaises(ValueError):
             Lockable.parse_requirements('a=')
         with self.assertRaises(ValueError):
             Lockable.parse_requirements('{"a":"b","c":"d}')
+        with self.assertRaises(ValueError):
+            Lockable.parse_requirements('{\na=b}')
 
     def test_lock_resource_not_found(self):
         with create_lockable([]) as lockable: