test_that("sdf works", {
  sdf <- igraph:::sdf
  `[.igraphSDF` <- igraph:::`[.igraphSDF`
  `[<-.igraphSDF` <- igraph:::`[<-.igraphSDF`
  as.data.frame.igraphSDF <- igraph:::as.data.frame.igraphSDF

  sdf <- sdf(id = 1:10, color = "black")
  expect_that(
    as.data.frame(sdf),
    equals(data.frame(id = 1:10, color = "black"))
  )

  ## access

  expect_that(sdf[1, "id"], equals(1))
  expect_that(sdf[1:4, "id"], equals(1:4))
  expect_that(sdf[, "id"], equals(1:10))

  expect_that(sdf[1, "color"], equals("black"))
  expect_that(sdf[1:4, "color"], equals(rep("black", 4)))
  expect_that(sdf[, "color"], equals(rep("black", 10)))

  ## set

  sdf2 <- sdf
  sdf2[5, "id"] <- 100
  expect_that(
    as.data.frame(sdf2),
    equals(data.frame(id = c(1:4, 100, 6:10), color = "black"))
  )

  sdf2 <- sdf
  sdf2[, "id"] <- 0
  expect_that(
    as.data.frame(sdf2),
    equals(data.frame(id = rep(0, 10), color = "black"))
  )

  sdf2 <- sdf
  sdf2[2:10, "id"] <- 1
  expect_that(
    as.data.frame(sdf2),
    equals(data.frame(id = rep(1, 10), color = "black"))
  )

  sdf2 <- sdf
  sdf2[, "color"] <- "white"
  expect_that(
    as.data.frame(sdf2),
    equals(data.frame(id = 1:10, color = "white"))
  )

  sdf2 <- sdf
  sdf2[5:6, "color"] <- "white"
  expect_that(
    as.data.frame(sdf2),
    equals(data.frame(id = 1:10, color = c(
      rep("black", 4),
      rep("white", 2),
      rep("black", 4)
    )))
  )
})