test_that("roll_median returns expected values for a simple centered example", {
  x <- c(1, 2, 3, 4, 5)

  result <- roll_median(x, 3, by = 1, align = "center")

  expect_equal(result, c(NA, 2, 3, 4, NA))
})

test_that("roll_median returns expected values for left alignment", {
  x <- c(1, 2, 3, 4, 5)

  result <- roll_median(x, 3, by = 1, align = "left")

  expect_equal(result, c(2, 3, 4, NA, NA))
})

test_that("roll_median returns expected values for right alignment", {
  x <- c(1, 2, 3, 4, 5)

  result <- roll_median(x, 3, by = 1, align = "right")

  expect_equal(result, c(NA, NA, 2, 3, 4))
})

test_that("roll_median respects the by argument", {
  x <- c(1, 2, 3, 4, 5, 6, 7)

  result <- roll_median(x, 3, by = 2, align = "center")

  expect_equal(result, c(NA, 2, NA, 4, NA, 6, NA))
})

test_that("roll_median with width 1 returns the input values", {
  x <- c(10, 20, 30, 40, 50)

  result <- roll_median(x, 1, by = 1, align = "center")

  expect_equal(result, x)
})

test_that("roll_median uses base R behavior for centered even widths", {
  x <- c(1, 2, 3, 4, 5, 6)

  result <- roll_median(x, 2, by = 1, align = "center")

  expect_equal(result, c(NA, 1.5, 2.5, 3.5, 4.5, 5.5))
})

test_that("roll_median returns a single centered value when even width equals input length", {
  x <- c(1, 2, 3, 4)

  result <- roll_median(x, 4, by = 1, align = "center")

  expect_equal(result, c(NA, NA, 2.5, NA))
})

test_that("roll_median returns a single value for left alignment when width equals input length", {
  x <- c(1, 2, 3, 4)

  result <- roll_median(x, 4, by = 1, align = "left")

  expect_equal(result, c(2.5, NA, NA, NA))
})

test_that("roll_median returns a single value for right alignment when width equals input length", {
  x <- c(1, 2, 3, 4)

  result <- roll_median(x, 4, by = 1, align = "right")

  expect_equal(result, c(NA, NA, NA, 2.5))
})

test_that("roll_median handles negative values correctly", {
  x <- c(-2, -1, 0, 1, 2)

  result <- roll_median(x, 3, by = 1, align = "center")

  expect_equal(result, c(NA, -1, 0, 1, NA))
})

test_that("roll_median handles decimal values correctly", {
  x <- c(0.5, 1.5, 2.5, 3.5, 4.5)

  result <- roll_median(x, 3, by = 1, align = "center")

  expect_equal(result, c(NA, 1.5, 2.5, 3.5, NA))
})

test_that("roll_median is robust to a single outlier", {
  x <- c(1, 2, 100, 4, 5)

  result <- roll_median(x, 3, by = 1, align = "center")

  expect_equal(result, c(NA, 2, 4, 5, NA))
})

test_that("roll_median matches base R median for an even window", {
  x <- c(1, 2, 3, 4)

  result <- roll_median(x, 4, by = 1, align = "left")

  expect_equal(result[1], median(x))
})