Handle incorrect keys

Signed-off-by: Aleksei Stepanov <penguinolog@gmail.com>

(cherry picked from commit 6aa67f8)
Signed-off-by: Aleksei Stepanov <penguinolog@gmail.com>

Author: penguinolog

doc/source/ExecResult.rst

@@ -193,6 +193,7 @@ API: ExecResult
         :type item: typing.Union[int, slice, typing.Iterable[typing.Union[int, slice, ellipsis]]]
         :returns: Joined selected lines
         :rtype: str
+        :raises KeyError: Unexpected key
 
     .. py:method:: __unicode__(self)
 

exec_helpers/exec_result.py

@@ -82,6 +82,7 @@ def __getitem__(
         :type item: typing.Union[int, slice, typing.Iterable[typing.Union[int, slice, ellipsis]]]
         :returns: Joined selected lines
         :rtype: str
+        :raises KeyError: Unexpected key
         """
         if isinstance(item, six.integer_types):
             return _get_str_from_bin(_get_bytearray_from_array([self._data[item]]))
@@ -93,8 +94,10 @@ def __getitem__(
                 buf.append(self._data[rule])
             elif isinstance(rule, slice):
                 buf.extend(self._data[rule])
-            else:
+            elif rule is Ellipsis:
                 buf.append(b"...\n")
+            else:
+                raise KeyError("Unexpected key: {rule!r} (from {item!r})".format(rule=rule, item=item))
         return _get_str_from_bin(_get_bytearray_from_array(buf))
 
     def __len__(self):  # type: () -> int  # pragma: no cover

test/test_exec_result.py

@@ -297,3 +297,5 @@ def test_indexed_lines_access(self):
         self.assertEqual(result.stdout_lines[0, 2], 'line0\nline2')
         self.assertEqual(result.stdout_lines[0, ..., 2], 'line0\n...\nline2')
         self.assertEqual(result.stdout_lines[:1, ..., 2], 'line0\n...\nline2')
+        with self.assertRaises(KeyError):
+            _ = result.stdout_lines[1, 'aaa']  # noqa