dplyr: A Grammar of Data Manipulation

context("Mutate")

test_that("repeated outputs applied progressively (data frame)", {
  df <- data.frame(x = 1)
  out <- mutate(df, z = x + 1, z = z + 1)

  expect_equal(nrow(out), 1)
  expect_equal(ncol(out), 2)

  expect_equal(out$z, 3)
})

test_that("repeated outputs applied progressively (grouped_df)", {
  df <- data.frame(x = c(1, 1), y = 1:2)
  ds <- group_by(df, y)
  out <- mutate(ds, z = x + 1, z = z + 1)

  expect_equal(nrow(out), 2)
  expect_equal(ncol(out), 3)

  expect_equal(out$z, c(3L, 3L))
})

test_that("two mutates equivalent to one", {
  df <- tibble(x = 1:10, y = 6:15)

  df1 <- df %>% mutate(x2 = x * 2, y4 = y * 4)
  df2 <- df %>% mutate(x2 = x * 2) %>% mutate(y4 = y * 4)

  expect_equal(df1, df2)
})

test_that("mutate can refer to variables that were just created (#140)", {
  res <- mutate(tbl_df(mtcars), cyl1 = cyl + 1, cyl2 = cyl1 + 1)
  expect_equal(res$cyl2, mtcars$cyl + 2)

  gmtcars <- group_by(tbl_df(mtcars), am)
  res <- mutate(gmtcars, cyl1 = cyl + 1, cyl2 = cyl1 + 1)
  res_direct <- mutate(gmtcars, cyl2 = cyl + 2)
  expect_equal(res$cyl2, res_direct$cyl2)
})

test_that("mutate handles logical result (#141)", {
  x <- data.frame(x = 1:10, g = rep(c(1, 2), each = 5))
  res <- tbl_df(x) %>% group_by(g) %>% mutate(r = x > mean(x))
  expect_equal(res$r, rep(c(FALSE, FALSE, FALSE, TRUE, TRUE), 2))
})

test_that("mutate can rename variables (#137)", {
  res <- mutate(tbl_df(mtcars), cyl2 = cyl)
  expect_equal(res$cyl2, mtcars$cyl)

  res <- mutate(group_by(tbl_df(mtcars), am), cyl2 = cyl)
  expect_equal(res$cyl2, res$cyl)
})

test_that("mutate refuses to modify grouping vars (#143)", {
  expect_error(
    mutate(group_by(tbl_df(mtcars), am), am = am + 2),
    "Column `am` can't be modified because it's a grouping variable",
    fixed = TRUE
  )
})

test_that("mutate handles constants (#152)", {
  res <- mutate(tbl_df(mtcars), zz = 1)
  expect_equal(res$zz, rep(1, nrow(mtcars)))
})

test_that("mutate fails with wrong result size (#152)", {
  df <- group_by(data.frame(x = c(2, 2, 3, 3)), x)
  expect_equal(mutate(df, y = 1:2)$y, rep(1:2, 2))
  expect_error(
    mutate(mtcars, zz = 1:2),
    "Column `zz` must be length 32 (the number of rows) or one, not 2",
    fixed = TRUE
  )

  df <- group_by(data.frame(x = c(2, 2, 3, 3, 3)), x)
  expect_error(
    mutate(df, y = 1:2),
    "Column `y` must be length 3 (the group size) or one, not 2",
    fixed = TRUE
  )
})

test_that("mutate refuses to use symbols not from the data", {
  y <- 1:6
  df <- group_by(data.frame(x = c(1, 2, 2, 3, 3, 3)), x)
  expect_error(
    mutate(df, z = y),
    "Column `z` must be length 1 (the group size), not 6",
    fixed = TRUE
  )
})

test_that("mutate recycles results of length 1", {
  df <- data.frame(x = c(2, 2, 3, 3))
  expect_equal(mutate(tbl_df(df), z = length(x))$z, rep(4, 4))
  expect_equal(mutate(group_by(df, x), z = length(x))$z, rep(2, 4))

  int  <- 1L
  str  <- "foo"
  num  <- 1
  bool <- TRUE
  list <- list(NULL)

  res <- mutate(group_by(df, x), int = int, str = str, num = num, bool = bool, list = list)
  expect_equal(res$int , rep(int , 4))
  expect_equal(res$str , rep(str , 4))
  expect_equal(res$num , rep(num , 4))
  expect_equal(res$bool, rep(bool, 4))
  expect_equal(res$list, rep(list, 4))
})


test_that("mutate handles out of data variables", {
  today <- Sys.Date()
  now <- Sys.time()
  df  <- data.frame(x = c(2, 2, 3, 3))
  gdf <- group_by(df, x)

  int  <- c(1L, 2L)
  str  <- c("foo", "bar")
  num  <- c(1, 2)
  bool <- c(TRUE, FALSE)
  dat  <- rep(today, 2)
  tim  <- rep(now, 2)

  res <- mutate(
    gdf,
    int = int, str = str, num = num, bool = bool, dat = dat, tim = tim
  )
  expect_equal(res$int , rep(int , 2))
  expect_equal(res$str , rep(str , 2))
  expect_equal(res$num , rep(num , 2))
  expect_equal(res$bool, rep(bool, 2))
  expect_equal(res$dat , rep(dat , 2))
  expect_equal(res$tim , rep(tim , 2))

  int <- 1:6
  expect_error(
    mutate(gdf, int = int),
    "Column `int` must be length 2 (the group size) or one, not 6",
    fixed = TRUE
  )
  expect_error(
    mutate(tbl_df(df), int = int),
    "Column `int` must be length 4 (the number of rows) or one, not 6",
    fixed = TRUE
  )

  int  <- 1:4
  str  <- rep(c("foo", "bar"), 2)
  num  <- c(1, 2, 3, 4)
  bool <- c(TRUE, FALSE, FALSE, TRUE)
  dat  <- rep(today, 4)
  tim  <- rep(now, 4)

  res <- mutate(
    tbl_df(df),
    int = int, str = str, num = num, bool = bool, tim = tim, dat = dat
  )
  expect_equal(res$int , int)
  expect_equal(res$str , str)
  expect_equal(res$num , num)
  expect_equal(res$bool, bool)
  expect_equal(res$dat , dat)
  expect_equal(res$tim , tim)
})

test_that("mutate handles passing ...", {
  df <- data.frame(x = 1:4)

  f <- function(...) {
    x1 <- 1
    f1 <- function(x) x
    mutate(df, ..., x1 = f1(x1))
  }
  g <- function(...) {
    x2 <- 2
    f(x2 = x2, ...)
  }
  h <- function(before = "before", ..., after = "after") {
    g(before = before, ..., after = after)
  }

  res <- h(x3 = 3)
  expect_equal(res$x1, rep(1, 4))
  expect_equal(res$x2, rep(2, 4))
  expect_equal(res$before, rep("before", 4))
  expect_equal(res$after, rep("after", 4))

  df <- tbl_df(df)
  res <- h(x3 = 3)
  expect_equal(res$x1, rep(1, 4))
  expect_equal(res$x2, rep(2, 4))
  expect_equal(res$before, rep("before", 4))
  expect_equal(res$after, rep("after", 4))

  df <- group_by(df, x)
  res <- h(x3 = 3)
  expect_equal(res$x1, rep(1, 4))
  expect_equal(res$x2, rep(2, 4))
  expect_equal(res$before, rep("before", 4))
  expect_equal(res$after, rep("after", 4))

})

test_that("mutate fails on unsupported column type", {
  df <- data.frame(created = c("2014/1/1", "2014/1/2", "2014/1/2"))
  expect_error(
    mutate(df, date = strptime(created, "%Y/%m/%d")),
    "Column `date` is of unsupported class POSIXlt",
    fixed = TRUE
  )

  df <- data.frame(
    created = c("2014/1/1", "2014/1/2", "2014/1/2"),
    g = c(1, 1, 2)
  )
  expect_error(
    mutate(group_by(df, g), date = strptime(created, "%Y/%m/%d")),
    "Column `date` is of unsupported class POSIXlt",
    fixed = TRUE
  )
})

test_that("mutate modifies same column repeatedly (#243)", {
  df <- data.frame(x = 1)
  expect_equal(mutate(df, x = x + 1, x = x + 1)$x, 3)
})

test_that("mutate errors when results are not compatible accross groups (#299)", {
  d <- data.frame(x = rep(1:5, each = 3))
  expect_error(
    mutate(group_by(d, x), val = ifelse(x < 3, "foo", 2)),
    "Column `val` can't be converted from character to numeric",
    fixed = TRUE
  )
})

test_that("assignments don't overwrite variables (#315)", {
   expect_equal(
     mutate(mtcars, cyl2 = { mpg <- cyl ^ 2; -mpg }),
     mutate(mtcars, cyl2 = -cyl ^ 2)
   )
})

test_that("hybrid evaluator uses correct environment (#403)", {
  func1 <- function() {
    func2 <- function(x) floor(x)
    mutate(mtcars, xx = func2(mpg / sum(mpg)))
  }
  res <- func1()
  expect_equal(res$xx, rep(0, nrow(res)))
})

test_that("mutate remove variables with = NULL syntax (#462)", {
  data <- mtcars %>% mutate(cyl = NULL)
  expect_false("cyl" %in% names(data))

  data <- mtcars %>% group_by(disp) %>% mutate(cyl = NULL)
  expect_false("cyl" %in% names(data))
})

test_that("mutate strips names, but only if grouped (#1689, #2675)", {
  data <- data_frame(a = 1:3) %>% mutate(b = setNames(nm = a))
  expect_equal(names(data$b), as.character(1:3))

  data <- data_frame(a = 1:3) %>% rowwise %>% mutate(b = setNames(nm = a))
  expect_null(names(data$b))

  data <- data_frame(a = c(1, 1, 2)) %>% group_by(a) %>% mutate(b = setNames(nm = a))
  expect_null(names(data$b))
})

test_that("mutate does not strip names of list-columns (#2675)", {
  vec <- list(a = 1, b = 2)
  data <- data_frame(x = vec)
  data <- mutate(data, x)
  expect_identical(names(vec), c("a", "b"))
  expect_identical(names(data$x), c("a", "b"))
})

test_that("mutate gives a nice error message if an expression evaluates to NULL (#2187)", {
  df <- data_frame(a = 1:3)
  gf <- group_by(df, a)
  rf <- rowwise(df)

  expect_error(
    mutate(df, b = identity(NULL)),
    "Column `b` is of unsupported type NULL",
    fixed = TRUE
  )
  expect_error(
    mutate(gf, b = identity(NULL)),
    "Column `b` is of unsupported type NULL",
    fixed = TRUE
  )
  expect_error(
    mutate(rf, b = identity(NULL)),
    "Column `b` is of unsupported type NULL",
    fixed = TRUE
  )
})

test_that("mutate(rowwise_df) makes a rowwise_df (#463)", {
  one_mod <- data.frame(grp = "a", x = runif(5, 0, 1)) %>%
    tbl_df %>%
    mutate(y = rnorm(x, x * 2, 1)) %>%
    group_by(grp) %>%
    do(mod = lm(y~x, data = .))

  out <- one_mod %>%
    mutate(rsq = summary(mod)$r.squared) %>%
    mutate(aic = AIC(mod))

  expect_is(out, "rowwise_df")
  expect_equal(nrow(out), 1L)
  expect_is(out$mod, "list")
  expect_is(out$mod[[1L]], "lm")
})

test_that("mutate allows list columns (#555)", {
  df  <- data.frame(x = c("a;b", "c;d;e"), stringsAsFactors = FALSE)
  res <- mutate(df, pieces = strsplit(x, ";"))
  expect_equal(res$pieces, list(c("a", "b"), c("c", "d", "e")))
})

test_that("hybrid evaluation goes deep enough (#554)", {
  res1 <- iris %>% mutate(test = 1 == 2 | row_number() < 10)
  res2 <- iris %>% mutate(test = row_number() < 10 | 1 == 2)
  expect_equal(res1, res2)
})

test_that("hybrid does not segfault when given non existing variable (#569)", {
  # error message from rlang
  expect_error(mtcars %>% summarise(first(mp)))
})

test_that("namespace extraction works in hybrid (#412)", {
  df <- data.frame(x = 1:2)

  expect_equal(
    mutate(df, y = base::mean(x)),
    mutate(df, y = mean(x))
  )
  expect_equal(
    mutate(df, y = stats::IQR(x)),
    mutate(df, y = IQR(x))
  )
})

test_that("hybrid not get in the way of order_by (#169)", {
  df <- data_frame(x = 10:1, y = 1:10)
  res <- mutate(df, z = order_by(x, cumsum(y)))
  expect_equal(res$z, rev(cumsum(10:1)))
})

test_that("mutate supports difftime objects (#390)", {
  df <- data_frame(
    grp =   c(1, 1,  2, 2),
    val =   c(1, 3,  4, 6),
    date1 = c(rep(Sys.Date() - 10, 2), rep(Sys.Date() - 20, 2)),
    date2 = Sys.Date() + c(1, 2, 1, 2),
    diffdate = difftime(date2, date1, unit = "days")
  )

  res <- df %>%
    group_by(grp) %>%
    mutate(mean_val = mean(val), mean_diffdate = mean(diffdate))
  expect_is(res$mean_diffdate, "difftime")
  expect_equal(as.numeric(res$mean_diffdate), c(11.5, 11.5, 21.5, 21.5))

  res <- df %>% group_by(grp) %>% summarise(dt = mean(diffdate))
  expect_is(res$dt, "difftime")
  expect_equal(as.numeric(res$dt), c(11.5, 21.5))
})

test_that("mutate works on zero-row grouped data frame (#596)", {
  dat <- data.frame(a = numeric(0), b = character(0))
  res <- dat %>% group_by(b) %>% mutate(a2 = a * 2)
  expect_is(res$a2, "numeric")
  expect_is(res, "grouped_df")
  expect_equal(res$a2, numeric(0))
  expect_equal(attr(res, "indices"), list())
  expect_equal(attr(res, "vars"), "b")
  expect_equal(attr(res, "group_sizes"), integer(0))
  expect_equal(attr(res, "biggest_group_size"), 0L)
})

test_that("Non-ascii column names in version 0.3 are not duplicated (#636)", {
  df <- data_frame(a = "1", b = "2")
  names(df) <- c("a", enc2native("\u4e2d"))

  res <- df %>% mutate_all(funs(as.numeric)) %>% names
  expect_equal(res, names(df))
})

test_that("nested hybrid functions do the right thing (#637)", {
  res <- mtcars %>% mutate(mean(1))
  expect_true(all(res[["mean(1)"]] == 1L))
})

test_that("mutate handles using and gathering complex data (#436)", {
  d <- data_frame(x = 1:10, y = 1:10 + 2i)
  res <- mutate(d, real = Re(y), imag = Im(y), z = 2 * y, constant = 2 + 2i)
  expect_equal(names(res), c("x", "y", "real", "imag", "z", "constant"))
  expect_equal(res$real, Re(d$y))
  expect_equal(res$imag, Im(d$y))
  expect_equal(res$z, d$y * 2)
  expect_true(all(res$constant == 2 + 2i))
})

test_that("mutate forbids POSIXlt results (#670)", {
  expect_error(
    data.frame(time = "2014/01/01 10:10:10") %>%
      mutate(time = as.POSIXlt(time)),
    "Column `time` is of unsupported class POSIXlt",
    fixed = TRUE
  )

  expect_error(
    data.frame(time = "2014/01/01 10:10:10", a = 2) %>%
      group_by(a) %>%
      mutate(time = as.POSIXlt(time)),
    "Column `time` is of unsupported class POSIXlt",
    fixed = TRUE
  )

})

test_that("constant factor can be handled by mutate (#715)", {
  d <- data_frame(x = 1:2) %>% mutate(y = factor("A"))
  expect_true(is.factor(d$y))
  expect_equal(d$y, factor(c("A", "A")))
})

test_that("row_number handles empty data frames (#762)", {
  df <- data.frame(a = numeric(0))
  res <- df %>% mutate(
    row_number_0 = row_number(),
    row_number_a = row_number(a),
    ntile = ntile(a, 2),
    min_rank = min_rank(a),
    percent_rank = percent_rank(a),
    dense_rank = dense_rank(a),
    cume_dist = cume_dist(a)
  )
  expect_equal(
    names(res),
     c("a", "row_number_0", "row_number_a", "ntile", "min_rank", "percent_rank", "dense_rank", "cume_dist")
   )
  expect_equal(nrow(res), 0L)
})

test_that("no utf8 invasion (#722)", {
  skip_on_os("windows")

  source("utf-8.R", local = TRUE, encoding = "UTF-8")
})

test_that("mutate works on empty data frames (#1142)", {
  df <- data.frame()
  res <- df %>% mutate
  expect_equal(nrow(res), 0L)
  expect_equal(length(res), 0L)

  res <- df %>% mutate(x = numeric())
  expect_equal(names(res), "x")
  expect_equal(nrow(res), 0L)
  expect_equal(length(res), 1L)
})

test_that("mutate handles 0 rows rowwise (#1300)", {
  a <- data_frame(x = 1)
  b <- data_frame(y = character())

  g <- function(y) {
    1
  }
  f <- function() {
    b %>% rowwise() %>% mutate(z = g(y))
  }

  res <- f()
  expect_equal(nrow(res), 0L)

  expect_error(
    a %>% mutate(b = f()),
    "Column `b` must be length 1 (the number of rows), not 2",
    fixed = TRUE
  )
  expect_error(
    a %>% rowwise() %>% mutate(b = f()),
    "Column `b` must be length 1 (the group size), not 2",
    fixed = TRUE
  )
})

test_that("regression test for #637", {
  res <- mtcars %>% mutate(xx = mean(1))
  expect_true(all(res$xx == 1))

  res <- mtcars %>% mutate(xx = sum(mean(mpg)))
  expect_true(all(res$xx == sum(mean(mtcars$mpg))))
})

test_that("mutate.rowwise handles factors (#886)", {
  res <- data.frame(processed = c("foo", "bar")) %>%
    rowwise() %>%
    mutate(processed_trafo = paste("test", processed))
  expect_equal(res$processed_trafo, c("test foo", "test bar"))
})

test_that("setting first column to NULL with mutate works (#1329)", {
  df <- data.frame(x = 1:10, y = 1:10)
  expect_equal(mutate(df, x = NULL), select(df, -x))
  expect_equal(mutate(df, y = NULL), select(df, -y))

  gdf <- group_by(df, y)
  expect_equal(select(gdf, -x), mutate(gdf, x = NULL))
})

test_that("mutate handles the all NA case (#958)", {
  x <- rep(c("Bob", "Jane"), each = 36)
  y <- rep(rep(c("A", "B", "C"), each = 12), 2)
  day <- rep(rep(1:12, 3), 2)
  values <- rep(rep(c(10, 11, 30, 12, 13, 14, 15, 16, 17, 18, 19, 20), 3), 2)

  df <- data.frame(x = x, y = y, day = day, values = values)
  df$values[1:12] <- NA

  res <- df %>%
    group_by(x, y) %>%
    mutate(max.sum = day[which.max(values)[1]]) %>%
    mutate(adjusted_values = ifelse(day < max.sum, 30, values))
  expect_true(all(is.na(res$adjusted_values[1:12])))
})

test_that("rowwise mutate gives expected results (#1381)", {
  f <- function(x) ifelse(x < 2, NA_real_, x)
  res <- data_frame(x = 1:3) %>% rowwise() %>% mutate(y = f(x))
  expect_equal(res$y, c(NA, 2, 3))
})

test_that("mutate handles factors (#1414)", {
  d <- data_frame(
    g = c(1, 1, 1, 2, 2, 3, 3),
    f = c("a", "b", "a", "a", "a", "b", "b")
  )
  res <- d %>% group_by(g) %>% mutate(f2 = factor(f, levels = c("a", "b")))
  expect_equal(as.character(res$f2), res$f)
})

test_that("mutate handles results from one group with all NA values (#1463) ", {
  df <- data_frame(x = c(1, 2), y = c(1, NA))
  res <- df %>% group_by(x) %>% mutate(z = ifelse(y > 1, 1, 2))
  expect_true(is.na(res$z[2]))
  expect_is(res$z, "numeric")
})

test_that("rowwise mutate handles the NA special case (#1448)", {
  res <- data.frame(k = c(-1, 1, 1)) %>%
    rowwise() %>%
    mutate(l = ifelse(k > 0, 1, NA))
  expect_is(res$l, "numeric")
  expect_true(is.na(res$l[1]))
  expect_true(!anyNA(res$l[-1]))

  res <- data.frame(k = rnorm(10)) %>%
    rowwise() %>%
    mutate(l = ifelse(k > 0, 1L, NA_integer_))
  expect_true(all(is.na(res$l[res$k <= 0])))
  expect_true(!any(is.na(res$l[res$k > 0])))
})

test_that("mutate disambiguates NA and NaN (#1448)", {
  Pass <- data.frame(P2 = c(0, 3, 2), F2 = c(0, 2, 0), id = 1:3)
  res <- Pass %>%
    group_by(id) %>%
    mutate(pass2 = P2 / (P2 + F2))
  expect_true(is.nan(res$pass2[1]))

  res <- Pass %>%
    rowwise %>%
    mutate(pass2 = P2 / (P2 + F2))
  expect_true(is.nan(res$pass2[1]))

  Pass <- data_frame(
    P1 = c(2L, 0L, 10L, 8L, 9L),
    F1 = c(0L, 2L, 0L, 4L, 3L),
    P2 = c(0L, 3L, 2L, 2L, 2L),
    F2 = c(0L, 2L, 0L, 1L, 1L),
    id = c(1, 2, 4, 4, 5)
  )

  res <- Pass %>%
    group_by(id) %>%
    mutate(
      pass_rate = (P1 + P2) / (P1 + P2 + F1 + F2) * 100,
      pass_rate1 = P1 / (P1 + F1) * 100,
      pass_rate2 = P2 / (P2 + F2) * 100
    )
  expect_true(is.nan(res$pass_rate2[1]))
})

test_that("hybrid evaluator leaves formulas untouched (#1447)", {
  d <- data_frame(g = 1:2, training = list(mtcars, mtcars * 2))
  mpg <- data.frame(x = 1:10, y = 1:10)
  res <- d %>%
    group_by(g) %>%
    mutate(lm_result = list(lm(mpg ~ wt, data = training[[1]])))
  expect_is(res$lm_result, "list")
  expect_is(res$lm_result[[1]], "lm")
  expect_is(res$lm_result[[2]], "lm")
})

test_that("lead/lag inside mutate handles expressions as value for default (#1411) ", {
  df <- data_frame(x = 1:3)
  res <- mutate(df, leadn = lead(x, default = x[1]), lagn = lag(x, default = x[1]))
  expect_equal(res$leadn, lead(df$x, default = df$x[1]))
  expect_equal(res$lagn, lag(df$x, default = df$x[1]))

  res <- mutate(df, leadn = lead(x, default = c(1)), lagn = lag(x, default = c(1)))
  expect_equal(res$leadn, lead(df$x, default = 1))
  expect_equal(res$lagn, lag(df$x, default = 1))
})

test_that("grouped mutate does not drop grouping attributes (#1020)", {
  d <- data.frame(subject = c("Jack", "Jill"), id = c(2, 1)) %>% group_by(subject)
  a1 <- names(attributes(d))
  a2 <- names(attributes(d %>% mutate(foo = 1)))
  expect_equal(setdiff(a1, a2), character(0))
})

test_that("grouped mutate coerces integer + double -> double (#1892)", {
  df <- data_frame(
    id = c(1, 4),
    value = c(1L, NA),
    group = c("A", "B")
  ) %>%
    group_by(group) %>%
    mutate(value = ifelse(is.na(value), 0, value))
  expect_type(df$value, "double")
  expect_identical(df$value, c(1, 0))
})

test_that("grouped mutate coerces factor + character -> character (WARN) (#1892)", {
  factor_or_character <- function(x)  {
    if (x > 3) {
      return(factor("hello"))
    } else {
      return("world")
    }
  }

  df <- data_frame(
    id = c(1, 4),
    group = c("A", "B")
  ) %>%
    group_by(group)
  expect_warning(
    df <- df %>%
      mutate(value = factor_or_character(id))
  )
  expect_type(df$value, "character")
  expect_identical(df$value, c("world", "hello"))
})

test_that("lead/lag works on more complex expressions (#1588)", {
  df <- data_frame(x = rep(1:5, 2), g = rep(1:2, each = 5)) %>% group_by(g)
  res <- df %>% mutate(y = lead(x > 3))
  expect_equal(res$y, rep(lead(1:5 > 3), 2))
})

test_that("Adding a Column of NA to a Grouped Table gives expected results (#1645)", {
  dataset <- data_frame(A = 1:10, B = 10:1, group = factor(sample(LETTERS[25:26], 10, TRUE)))
  res <- dataset %>% group_by(group) %>% mutate(prediction = factor(NA))
  expect_true(all(is.na(res$prediction)))
  expect_is(res$prediction, "factor")
  expect_equal(levels(res$prediction), character())
})

test_that("Deep copies are performed when needed (#1463)", {
  res <- data.frame(prob = c(F, T)) %>%
    rowwise %>%
    mutate(model = list(x = prob))
  expect_equal(unlist(res$model), c(FALSE, TRUE))

  res <- data.frame(x = 1:4, g = c(1, 1, 1, 2)) %>%
    group_by(g) %>%
    mutate(model = list(y = x))
  expect_equal(res$model[[1]], 1:3)
  expect_equal(res$model[[4]], 4)
})

test_that("ntile falls back to R (#1750)", {
  res <- mutate(iris, a = ntile("Sepal.Length", 3))
  expect_equal(res$a, rep(1, 150))
})

test_that("mutate() names pronouns correctly (#2686)", {
  expect_named(mutate(tibble(x = 1), .data$x), "x")
  expect_named(mutate(tibble(x = 1), .data[["x"]]), "x")
})


# Error messages ----------------------------------------------------------

test_that("mutate fails gracefully on non-vector columns (#1803)", {
  df <- data_frame(a = 1:3, b = as.raw(1:3))
  expect_error(
    mutate(df, a = 1),
    "Column `b` is of unsupported type raw vector",
    fixed = TRUE
  )
  expect_error(
    mutate(df, b = 1),
    "Column `b` is of unsupported type raw vector",
    fixed = TRUE
  )
  expect_error(
    mutate(df, c = 1),
    "Column `b` is of unsupported type raw vector",
    fixed = TRUE
  )
})

test_that("grouped mutate errors on incompatible column type (#1641)", {
  expect_error(
    tibble(x = 1) %>% mutate(y = mean),
    "Column `y` is of unsupported type function",
    fixed = TRUE
  )
  expect_error(
    tibble(x = 1) %>% mutate(y = quote(a)),
    "Column `y` is of unsupported type symbol",
    fixed = TRUE
  )
})