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"), "[]");
});