test_that("we can convert numbers to unit-less units", {
  x <- as_units(1:4)
  expect_equal(length(x), 4)
  expect_equal(class(x), "units")
  expect_equal(as.numeric(x), 1:4)

  y <- 1:4
  units(y) <- unitless
  expect_equal(x, y)
})

test_that("we can convert numbers to physical units", {
  m <- as_units("m")
  x <- 1:4 * m
  expect_equal(length(x), 4)
  expect_equal(class(x), "units")
  expect_equal(as.character(units(x)), "m")
  expect_equal(as.numeric(x), 1:4)

  y <- 1:4
  units(y) <- m
  expect_equal(x, y)

  z <- 1:4 / m
  expect_equal(length(z), 4)
  expect_equal(class(z), "units")
  expect_equal(as.character(units(z)), "1/m")
  expect_equal(as.numeric(z), 1:4)
})

test_that("we can convert NA values to physical units", {
  m <- as_units("m")
  x <- NA * m
  expect_equal(class(x), "units")
  expect_equal(as.character(units(x)), "m")
  expect_equal(as.numeric(x), as.numeric(NA))

  x <- set_units(NA,m/s)
  expect_equal(as.character(units(x)), "m/s")
  expect_equal(x + set_units(5,m/s), set_units(NA,m/s))
  expect_error(x + set_units(5,m))

  x <- NA
  units(x) <- m
  expect_equal(as.character(units(x)), 'm')

  x <- rep(NA,5)
  s <- as_units("s")
  units(x) <- make_units(m/s)
  expect_equal(length(x),5)
  expect_equal(units(x),units(m/s))
  expect_equal(x,5 * x)
  expect_error(x + 1)
})

test_that("we can convert between two units that can be converted", {
  m <- as_units("m")
  km <- as_units("km")
  x <- y <- 1:4 * m
  units(x) <- km
  expect_equal(as.numeric(y), 1000 * as.numeric(x))
  skip_if_not_installed("magrittr")
  `%>%` <- magrittr::`%>%`
  y %>% set_units(km) -> z
  expect_equal(x, z)
})

test_that("we can't convert between two units that can't be converted", {
  m <- as_units("m")
  s <- as_units("s")
  expect_error(units(m) <- s)
})

test_that("we can convert difftime objects to units", {
  s <- Sys.time()
  d <- s - (s + 1)
  x <- as_units(d)
  expect_equal(as.numeric(x), as.numeric(d))

  week <- as.difftime(1, units = "weeks")
  units_week <- as_units(week)
  expect_equal(as.character(units(units_week)), "d")
  expect_equal(as.numeric(units_week), 7)
})

test_that("we can convert units objects to difftime objects", {
  s <- Sys.time()
  d <- s - (s + 1)
  x <- as_units(d)
  y <- as_difftime(x)

  expect_equal(d, y)
})

#test_that("we can convert units objects to and from hms objects", {
#  s <- Sys.time()
#  library(hms)
#  d <- as.hms(s - (s + 1))
#  x <- as_units(d)
#  y <- as.hms(x)
#
#  expect_equal(d, y)
#})

test_that("we can subscript units", {
  x <- 1:4
  y <- x * as_units("m")
  expect_equal(as.numeric(y[1]), x[1])
  expect_equal(class(y[1]), class(y))
  expect_equal(as.numeric(y[[1]]), x[[1]])
  expect_equal(class(y[[1]]), class(y))
})

test_that("m + m*s is an error", {
  m <- as_units("m")
  s <- as_units("s")
  expect_error(m + m * s)
})

test_that("we can convert between units that are not simply a scalar from each other", {
  m <- 0 * as_units("degC")
  units(m) <- as_units("degK")
  expect_equal(as.numeric(m), units:::ud_convert(0, "degC", "degK"))
  expect_equal(as.character(units(m)), "K")

  ## Does this make any sense??
  # temp <- 75 * as_units('degF')
  # units(temp) <- as_units('degK')
  # result <- temp / as_units('degF')
  # expect_equal(as.numeric(result), 75)
  # expect_equal(units(result), unitless)
})

test_that("dim propagates", {
  y = x = set_units(matrix(1:4,2), m)
  units(y) = as_units("mm")
  expect_equal(dim(x), dim(y))
})

test_that("conversion of g/kg to dimensionless is not the default", {
	a_orig <- a <- 1:10
	units(a) = as_units("mg/kg")
	expect_equal(as.numeric(a), a_orig)
})

test_that("conversion to dimensionless with prefix works (g/kg) if simplify=TRUE", {
	a_orig <- a <- 1:10
	units_options(simplify = TRUE)
	units(a) = as_units("mg/kg")
	expect_equal(as.numeric(a), a_orig/1e6)
	units(a) = as_units("kg/mg")
	expect_equal(a, set_units(a_orig, 1))
	units(a) = as_units("g/g")
	expect_equal(a, set_units(a_orig, 1))
	units(a) = as_units("kg/g")
	expect_equal(a, set_units(a_orig * 1000, 1))
	units_options(simplify = NA)
})

test_that("a NULL value returns NULL", {
  expect_null(as_units(NULL))
})

test_that("as.data.frame.units works", {
  x <- matrix(1:9, 3)

  df1 <- as.data.frame(x)
  for (col in names(df1))
    df1[[col]] <- set_units(df1[[col]], m)
  df2 <- as.data.frame(set_units(x, m))

  expect_equal(df1, df2)
})

test_that("units.symbolic_units works", {
  m = set_units(1, m)
  expect_equal(units(m), units(units(m)))
})

test_that("new base units work", {
  install_unit("person")
  expect_equal(set_units(1, person) + set_units(1, kperson), set_units(1001, person))
  expect_error(set_units(1, person) + set_units(1, rad), "cannot convert")

  # restore
  remove_unit("person")
})

test_that("errors are correctly coerced to a data frame", {
  a <- 1:10
  b <- a * as_units("m")

  expect_equal(as.data.frame(b)$b, b)
  x <- data.frame(a, b)
  expect_equal(x$a, a)
  expect_equal(x$b, b)
  x <- cbind(x, a, data.frame(b))
  expect_equal(x[[3]], a)
  expect_equal(x[[4]], b)
  x <- rbind(x, a[1:4], x[1,])
  expect_equal(x[[1]], c(a, 1, 1))
  expect_equal(x[[2]], c(b, c(2, 1) * as_units("m")))
  expect_equal(x[[3]], c(a, 3, 1))
  expect_equal(x[[4]], c(b, c(4, 1) * as_units("m")))
})

test_that("units are correctly coerced to a list", {
  x <- 1:10 * as_units("m")
  y <- as.list(x)
  expect_type(y, "list")
  expect_true(all(sapply(seq_along(y), function(i) all.equal(y[[i]], x[i]))))
})

test_that("NA as units generate warnings", {
  expect_error(set_units(NA_real_, NA_character_, mode="standard"), "a missing value for units is not allowed")
  expect_error(set_units(NA_real_, NA, mode="standard"), "a missing value for units is not allowed")
})

test_that("set_units keeps names even with unit conversion (#305)", {
  expect_named(set_units(c(a=1), "m"), "a")
  expect_named(
    set_units(set_units(c(a=1), "m"), "km"),
    "a"
  )
})

test_that("conversion to mixed_units", {
  a <- set_units(1:3, m/s)
  expect_s3_class(a, "units")
  units(a) <- c("m/s", "km/h", "km/h")
  expect_s3_class(a, "mixed_units")
  expect_equal(
    drop_units(a),
    c(1, 0.002*3600, 0.003*3600)
  )
})