test_that("I can index a vs twice", {
  edges <- data.frame(
    stringsAsFactors = TRUE,
    from = c("BOS", "JFK", "DEN", "BOS", "JFK", "DEN"),
    to = c("JFK", "DEN", "ABQ", "JFK", "DEN", "ABQ"),
    carrier = c("foo", "foo", "foo", "bar", "bar", "bar")
  )

  vertices <- data.frame(
    stringsAsFactors = TRUE,
    id = c("BOS", "JFK", "DEN", "ABQ"),
    state = c("MA", "NY", "CO", "NM")
  )

  g <- graph_from_data_frame(edges, vertices = vertices)

  x <- V(g)[3:4][state == "NM"]

  expect_equal(ignore_attr = TRUE, x, V(g)["ABQ"])
})

test_that("I can index an es twice", {
  edges <- data.frame(
    stringsAsFactors = TRUE,
    from = c("BOS", "JFK", "DEN", "BOS", "JFK", "DEN"),
    to = c("JFK", "DEN", "ABQ", "JFK", "DEN", "ABQ"),
    carrier = c("foo", "foo", "foo", "bar", "bar", "bar")
  )

  g <- graph_from_data_frame(edges)

  x <- E(g)["BOS" %->% "JFK"][carrier == "foo"]

  expect_equal(ignore_attr = TRUE, x, E(g)[carrier == "foo" & .from("BOS") & .to("JFK")])
})