test_that("pmm picks the right reference based on numeric values", {
  expect_equal(
    pmm(xtrain = c(0.2, 0.2, 0.8), xtest = 0.3, ytrain = c(0, 0, 1)), 0
  )
  expect_equal(pmm(1:10, 3:4, 1:10), 3:4)
})

test_that("pmm picks the right reference based on logical values", {
  expect_equal(
    pmm(xtrain = c(TRUE, FALSE, TRUE), xtest = FALSE, ytrain = c(2, 0, 1)), 0
  )
})

test_that("pmm picks the right reference based on character values", {
  expect_equal(
    pmm(xtrain = c("A", "A", "B"), xtest = "A", ytrain = c(2, 2, 4), k = 2), 2
  )
})

test_that("pmm picks the right reference based on a factor", {
  expect_equal(pmm(xtrain = factor(c("A", "B")), xtest = factor("C"), ytrain = 1:2), 2)
})

test_that("pmm picks the right reference based on date vector", {
  xtrain <- as.Date(c("2018-01-01", "2018-01-02"))
  xquery <- as.Date(c("2018-01-03", "2018-01-04"))
  expect_equal(pmm(xtrain, xquery, ytrain = 1:2), rep(2, 2))
})

test_that("pmm gives error if ytrain is of wrong length", {
  expect_error(pmm(xtrain = 1, xtest = 1, ytrain = 1:2))
})

test_that("pmm works for logical y", {
  expect_equal(pmm(1, xtest = Sys.Date(), ytrain = TRUE), TRUE)
})

test_that("pmm works for factor y", {
  expect_equal(pmm(1, xtest = Sys.Date(), ytrain = factor("A")), factor("A"))
})

test_that("pmm works for date y", {
  expect_equal(pmm(1, xtest = Sys.Date(), ytrain = Sys.Date()), Sys.Date())
})

test_that("pmm works with NA in xtrain", {
  expect_equal(pmm(c(NA, 1, 2), 1, ytrain = c(0, 1, NA)), 1)
})

test_that("pmm works with NA in xtrain and NA in ytrain", {
  expect_equal(pmm(c(NA, 1, 2), 1, ytrain = c(0, NA, 3)), 3)
})

test_that("pmm gives error when xtest contains NA", {
  expect_error(pmm(c(1, 1, 2), NA, ytrain = c(0, 1, 2)))
})