# Tests for plot_lag function

test_that("plot_lag creates ggplot object", {
  dat <- simulate_invasion(seed = 123)
  result <- detect_lag(dat$year, dat$count)

  p <- plot_lag(result)

  expect_s3_class(p, "ggplot")
})

test_that("plot_lag handles different types", {
  dat <- simulate_invasion(seed = 123)
  result <- detect_lag(dat$year, dat$count)

  p_main <- plot_lag(result, type = "main")
  p_phases <- plot_lag(result, type = "phases")

  expect_s3_class(p_main, "ggplot")
  expect_s3_class(p_phases, "ggplot")
})

test_that("plot_lag handles different themes", {
  dat <- simulate_invasion(seed = 123)
  result <- detect_lag(dat$year, dat$count)

  p_minimal <- plot_lag(result, theme = "minimal")
  p_classic <- plot_lag(result, theme = "classic")
  p_pub <- plot_lag(result, theme = "publication")

  expect_s3_class(p_minimal, "ggplot")
  expect_s3_class(p_classic, "ggplot")
  expect_s3_class(p_pub, "ggplot")
})

test_that("plot.invalag method works", {
  dat <- simulate_invasion(seed = 123)
  result <- detect_lag(dat$year, dat$count)

  p <- plot(result)

  expect_s3_class(p, "ggplot")
})

test_that("plot_lag validates input", {
  expect_error(plot_lag("not an invalag object"))
  expect_error(plot_lag(list(a = 1, b = 2)))
})