How to use the prance.util.path.path_get function in prance

value = 42

  # No path can be resolved in a value type
  result = None
  with pytest.raises(TypeError):
    result = path_get(value, ('foo', 'bar'), 123)
  assert result is None

  # However, we can resolve zero length paths
  result = path_get(value, (), 123)
  assert 42 == result
  result = path_get(None, (), 123)
  assert 123 == result

  # Also we can resolve None-type paths
  result = path_get(value, None, 321)
  assert 42 == result
  result = path_get(None, None, 321)
  assert 321 == result

def test_get_mapping_default():
  value = { 'foo': 1, 'bar': 2, 3: 3 }

  # String paths should work in a Mapping
  result = path_get(value, ('foo',), 123)
  assert 1 == result

  # So should numeric keys
  result = path_get(value, (3,), 123)
  assert 3 == result

  # Zero length paths should return the value or default value
  result = path_get(value, (), 123)
  assert { 'foo': 1, 'bar': 2, 3: 3 } == result
  result = path_get(None, (), 123)
  assert 123 == result

  # And None paths as well
  result = path_get(value, None, 321)
  assert { 'foo': 1, 'bar': 2, 3: 3 } == result
  result = path_get(None, None, 321)
  assert 321 == result

# By default, all externals need to be resolved.
  from prance.util.path import path_get

  val = path_get(res.specs, ('paths', '/pets', 'get', 'responses', '200', 'schema'))
  assert '$ref' not in val

  val = path_get(res.specs, ('paths', '/pets', 'get', 'responses', 'default', 'schema'))
  assert '$ref' not in val

  val = path_get(res.specs, ('paths', '/pets', 'post', 'responses', 'default', 'schema'))
  assert '$ref' not in val

  val = path_get(res.specs, ('paths', '/pets/{petId}', 'get', 'parameters', 0))
  assert '$ref' not in val

  val = path_get(res.specs, ('paths', '/pets/{petId}', 'get', 'responses', '200', 'schema'))
  assert '$ref' in val

  val = path_get(res.specs, ('paths', '/pets/{petId}', 'get', 'responses', 'default', 'schema'))
  assert '$ref' in val

# By default, all externals need to be resolved.
  from prance.util.path import path_get

  val = path_get(res.specs, ('paths', '/pets', 'get', 'responses', '200', 'schema'))
  assert '$ref' in val

  val = path_get(res.specs, ('paths', '/pets', 'get', 'responses', 'default', 'schema'))
  assert '$ref' in val

  val = path_get(res.specs, ('paths', '/pets', 'post', 'responses', 'default', 'schema'))
  assert '$ref' in val

  val = path_get(res.specs, ('paths', '/pets/{petId}', 'get', 'parameters', 0))
  assert '$ref' in val

  val = path_get(res.specs, ('paths', '/pets/{petId}', 'get', 'responses', '200', 'schema'))
  assert '$ref' in val

  val = path_get(res.specs, ('paths', '/pets/{petId}', 'get', 'responses', 'default', 'schema'))
  assert '$ref' not in val

def test_get_collection_default():
  value = (1, 2, 3)

  # String paths in a Sequence should raise KeyError
  result = None
  with pytest.raises(KeyError):
    result = path_get(value, ('foo', 'bar'), 123)
  assert result is None

  # A numeric path should work, though
  result = path_get(value, (1,), 123)
  assert 2 == result

  # Zero length paths should return the value or default value
  result = path_get(value, (), 123)
  assert (1, 2, 3) == result
  result = path_get(None, (), 123)
  assert 123 == result

  # And None paths as well
  result = path_get(value, None, 321)
  assert (1, 2, 3) == result
  result = path_get(None, None, 321)
  assert 321 == result

def test_get_informative_index_error():
  base = { 'foo': { 'bar': [123] } }

  with pytest.raises(IndexError, match = r'.*"/foo/bar".*123'):
    path_get(base, ('foo', 'bar', 123))

:param list obj_path: The object path within the URL resource.
    :param tuple recursions: A recursion stack for resolving references.
    :return: A copy of the dereferenced value, with all internal references
        resolved.
    """
    # In order to start dereferencing anything in the referenced URL, we have
    # to read and parse it, of course.
    contents = _url.fetch_url(ref_url, self.__reference_cache)

    # In this inner parser's specification, we can now look for the referenced
    # object.
    value = contents
    if len(obj_path) != 0:
      from prance.util.path import path_get
      try:
        value = path_get(value, obj_path)
      except KeyError:
        raise _url.ResolutionError('Cannot resolve reference "%s"!'
            % (ref_url.geturl(), ))

    # Deep copy value; we don't want to create recursive structures
    import copy
    value = copy.deepcopy(value)

    # Now resolve partial specs
    value = self._resolve_partial(ref_url, value, recursions)

    # That's it!
    return value