test_that("graph_from_data_frame works", {
  local_igraph_options(print.full = TRUE)

  actors <- data.frame(
    name = c(
      "Alice", "Bob", "Cecil", "David",
      "Esmeralda"
    ),
    age = c(48, 33, 45, 34, 21),
    gender = c("F", "M", "F", "M", "F"),
    stringsAsFactors = FALSE
  )
  relations <- data.frame(
    from = c(
      "Bob", "Cecil", "Cecil", "David",
      "David", "Esmeralda"
    ),
    to = c(
      "Alice", "Bob", "Alice", "Alice",
      "Bob", "Alice"
    ),
    same.dept = c(FALSE, FALSE, TRUE, FALSE, FALSE, TRUE),
    friendship = c(4, 5, 5, 2, 1, 1), advice = c(4, 5, 5, 4, 2, 3),
    stringsAsFactors = FALSE
  )
  g <- graph_from_data_frame(relations, directed = TRUE, vertices = actors)

  df <- as_data_frame(g, what = "both")
  expect_equal(df$vertices, actors, ignore_attr = TRUE)
  expect_equal(df$edges, relations)
})

test_that("graph_from_data_frame() creates attributes for zero-row data frames (#466)", {
  x <- data.frame(from = integer(), to = integer(), foo = integer(), bar = numeric())
  g <- graph_from_data_frame(x)
  expect_identical(E(g)$foo, integer())
  expect_identical(E(g)$bar, numeric())
})

test_that("graph_from_data_frame works on matrices", {
  el <- cbind(1:5, 5:1, weight = 1:5)
  g <- graph_from_data_frame(el)
  g <- delete_vertex_attr(g, "name")
  el2 <- as_data_frame(g)
  expect_equal(as.data.frame(el), el2, ignore_attr = TRUE)
})

test_that("as_long_data_frame() works correctly with and without names", {
  expect_snapshot({
    ring <- make_ring(3)
    as_long_data_frame(ring)

    V(ring)$name <- letters[1:3]
    as_long_data_frame(ring)

    V(ring)$score <- LETTERS[1:3]
    as_long_data_frame(ring)

    E(ring)$info <- 3:1
    as_long_data_frame(ring)
  })
})