test_that("Encoding Factor Objects", {
  expect_identical(toJSON(character()), "[]")
  expect_identical(toJSON(logical()), "[]")
  expect_identical(toJSON(complex()), "[]")
  expect_identical(toJSON(complex(), complex = "list"), "{\"real\":[],\"imaginary\":[]}")
  expect_identical(toJSON(double()), "[]")
  expect_identical(toJSON(integer()), "[]")
  expect_identical(toJSON(list()), "[]")
  expect_identical(toJSON(factor()), "[]")
  expect_identical(toJSON(factor(levels = c("foo", "bar"))), "[]")
  expect_identical(toJSON(matrix(nrow = 0, ncol = 0)), "[]")
  expect_identical(toJSON(as.matrix(numeric())), "[]")
  expect_identical(toJSON(data.frame()), "[]")
  expect_identical(toJSON(data.frame(foo = vector())), "[]")
  expect_identical(toJSON(data.frame(foo = vector(), bar = logical())), "[]")
  expect_identical(toJSON(Sys.time()[0], POSIXt = "string"), "[]")
  expect_identical(toJSON(Sys.time()[0], POSIXt = "epoch"), "[]")
  expect_identical(toJSON(Sys.time()[0], POSIXt = "mongo"), "[]")
  expect_identical(toJSON(Sys.time()[0], POSIXt = "ISO8601"), "[]")
  expect_identical(toJSON(as.Date(Sys.time())[0], POSIXt = "ISO8601"), "[]")
})