Fix redundant yaml error blurbs on ModArgs parse errors

lib/ansible/playbook/task.py

@@ -184,6 +184,11 @@ def preprocess_data(self, ds):
         try:
             (action, args, delegate_to) = args_parser.parse()
         except AnsibleParserError as e:
+            # if the raises exception was created with obj=ds args, then it includes the detail
+            # so we dont need to add it so we can just re raise.
+            if e._obj:
+                raise
+            # But if it wasn't, we can add the yaml object now to get more detail
             raise AnsibleParserError(to_native(e), obj=ds, orig_exc=e)
 
         # the command/shell/script modules used to support the `cmd` arg,

test/units/playbook/test_task.py

@@ -20,7 +20,10 @@
 __metaclass__ = type
 
 from ansible.compat.tests import unittest
+from ansible.compat.tests.mock import patch
 from ansible.playbook.task import Task
+from ansible.parsing.yaml import objects
+from ansible import errors
 
 
 basic_command_task = dict(
@@ -32,6 +35,10 @@
     action='command echo hi'
 )
 
+# See #36848
+kv_bad_args_str = '- apk: sdfs sf sdf 37'
+kv_bad_args_ds = {'apk': 'sdfs sf sdf 37'}
+
 
 class TestTask(unittest.TestCase):
 
@@ -42,7 +49,7 @@ def tearDown(self):
         pass
 
     def test_construct_empty_task(self):
-        t = Task()
+        Task()
 
     def test_construct_task_with_role(self):
         pass
@@ -65,9 +72,27 @@ def test_load_task_kv_form(self):
         self.assertEqual(t.action, 'command')
         self.assertEqual(t.args, dict(_raw_params='echo hi'))
 
+    @patch.object(errors.AnsibleError, '_get_error_lines_from_file')
+    def test_load_task_kv_form_error_36848(self, mock_get_err_lines):
+        ds = objects.AnsibleMapping(kv_bad_args_ds)
+        ds.ansible_pos = ('test_task_faux_playbook.yml', 1, 1)
+        mock_get_err_lines.return_value = (kv_bad_args_str, '')
+
+        with self.assertRaises(errors.AnsibleParserError) as cm:
+            Task.load(ds)
+
+        self.assertIsInstance(cm.exception, errors.AnsibleParserError)
+        self.assertEqual(cm.exception._obj, ds)
+        self.assertEqual(cm.exception._obj, kv_bad_args_ds)
+        self.assertIn("The error appears to have been in 'test_task_faux_playbook.yml", cm.exception.message)
+        self.assertIn(kv_bad_args_str, cm.exception.message)
+        self.assertIn('apk', cm.exception.message)
+        self.assertEquals(cm.exception.message.count('The offending line'), 1)
+        self.assertEquals(cm.exception.message.count('The error appears to have been in'), 1)
+
     def test_task_auto_name(self):
         assert 'name' not in kv_command_task
-        t = Task.load(kv_command_task)
+        Task.load(kv_command_task)
         # self.assertEqual(t.name, 'shell echo hi')
 
     def test_task_auto_name_with_role(self):