test_that("computes spanning tree", {
  x <- 1:10
  y <- list(x, x, x)
  obj <- sxp(y)

  expect_false(attr(obj[[1]], "has_seen"))
  expect_true(attr(obj[[2]], "has_seen"))
})

test_that("captures names of special environments", {
  x <- list(
    emptyenv(),
    baseenv(),
    globalenv()
  )
  obj <- sxp(x)
  expect_equal(attr(obj[[1]], "value"), "empty")
  expect_equal(attr(obj[[2]], "value"), "base")
  expect_equal(attr(obj[[3]], "value"), "global")
})

test_that("captures names of lists", {
  x <- list(a = 1, b = 2, c = 3)
  obj <- sxp(x)
  expect_named(obj, c(names(x), "_attrib"))
})

test_that("can expand lists", {
  x <- c("xxx", "xxx", "y")
  obj <- sxp(x, expand = "character")

  expect_length(obj, 3)
  expect_equal(attr(obj[[1]], "ref"), attr(obj[[2]], "ref"))
})

test_that("can inspect active bindings", {
  e <- new.env(hash = FALSE)
  env_bind_active(e, f = function() stop("!"))

  x <- sxp(e)
  expect_named(x, c("f", "_enclos"))
})

# Regression tests --------------------------------------------------------

test_that("can inspect all atomic vectors", {
  x <- list(
    TRUE,
    1L,
    1,
    "3",
    1i,
    raw(1)
  )
  expect_snapshot(sxp(x))
})

test_that("can inspect functions", {
  f <- function(x, y = 1, ...) x + 1
  attr(f, "srcref") <- NULL
  environment(f) <- globalenv()

  expect_snapshot(sxp(f))
})

test_that("can inspect environments", {
  e1 <- new.env(parent = emptyenv(), size = 5L)
  e1$x <- 10
  e1$y <- e1

  e2 <- new.env(parent = e1, size = 5L)

  expect_snapshot({
    print(sxp(e2))
    print(sxp(e2, expand = "environment", max_depth = 5L))
  })
})

test_that("can expand altrep", {
  skip_if_not(getRversion() >= "3.5")
  skip_if_not(.Machine$sizeof.pointer == 8) # _class RAWSXP has different size

  expect_snapshot({
    x <- 1:10
    print(sxp(x, expand = "altrep", max_depth = 4L))
  })
})

test_that("can inspect cons cells", {
  expect_snapshot({
    cell <- new_node(1, 2)
    sxp(cell)

    non_nil_terminated_list <- new_node(1, new_node(2, 3))
    sxp(non_nil_terminated_list)
  })
})

test_that("fix error message when `expand` argument contains invalid classes", {
  expect_snapshot(error = TRUE, {
    sxp(1, expand = "invalid_class")
  })
})